US20020038435A1 - Semiconductor integrated circuit system for high-speed data transfer in syschronization with a predetermined clock - Google Patents
Semiconductor integrated circuit system for high-speed data transfer in syschronization with a predetermined clock Download PDFInfo
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- US20020038435A1 US20020038435A1 US09/115,716 US11571698A US2002038435A1 US 20020038435 A1 US20020038435 A1 US 20020038435A1 US 11571698 A US11571698 A US 11571698A US 2002038435 A1 US2002038435 A1 US 2002038435A1
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- G—PHYSICS
- G06—COMPUTING OR CALCULATING; COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F1/00—Details not covered by groups G06F3/00 - G06F13/00 and G06F21/00
- G06F1/02—Digital function generators
- G06F1/025—Digital function generators for functions having two-valued amplitude, e.g. Walsh functions
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
- G11C11/34—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices
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- G—PHYSICS
- G06—COMPUTING OR CALCULATING; COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F1/00—Details not covered by groups G06F3/00 - G06F13/00 and G06F21/00
- G06F1/04—Generating or distributing clock signals or signals derived directly therefrom
- G06F1/10—Distribution of clock signals, e.g. skew
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
Definitions
- the present invention relates to a semiconductor integrated circuit system, a semiconductor integrated circuit and a method for driving a semiconductor integrated circuit system. More particularly, the present invention relates to a semiconductor integrated circuit system for high-speed data transfer in synchronization with a clock, a method for driving such a semiconductor integrated circuit system, and a semiconductor integrated circuit for use in such a semiconductor integrated circuit system.
- the slave chips are each provided with a circuit for delaying (or adjusting the phase of) the data output clock for controlling the timing of data output based on the positional relationship with (or the bus length to) the master chip, as illustrated in Draft 0.99 IEEE P1596.7-199X, P.43, FIG. 36, for example.
- the distance from each slave chip to the master chip is detected at initialization of the system, so that a predetermined amount of delay in accordance with the distance is set in a circuit for adjusting the phase of the clock (hereinafter, referred to simply as the “clock phase adjustment circuit”) in the slave chip.
- the phase of the data output clock of each slave chip is adjusted as described above, so that the master chip can receive data from respective slave chips simultaneously, whereby it is possible to stably perform high-speed data transfer.
- such a conventional integrated circuit system as described above may include IC chips (semiconductor integrated circuits) which are not all from the same manufacturer.
- the characteristics (e.g., the temperature dependency or source voltage dependency) of the data output clock phase adjustment circuit provided in one IC chip may differ from those of another IC chip.
- the inventors of the present invention found that such difference in the characteristics of the data output clock phase adjustment circuit among the IC chips is particularly problematic in systems for high-speed data transfer such as those operating at a clock frequency of 200 MHz or higher.
- Such a change in the temperature or source voltage in a semiconductor integrated circuit system can easily occur, for example, due to the increasing temperature during use or when running an application with a large power consumption.
- a semiconductor integrated circuit system having one master chip and a plurality of slave chips, for performing data transfer under a control of a predetermined clock.
- the system includes: a detection section for detecting a change in a state of the semiconductor integrated circuit system and for producing information indicating the detection result, the state including at least one of temperature and source voltage; and at least one clock phase adjustment section for receiving the information and for adjusting a phase of a clock used in transferring data output by the slave chip based on the information.
- the detection section is controlled by the master chip, and the at least one clock phase adjustment section is included in the slave chip.
- the master chip and the plurality of slave chips are each connected to a command bus for transferring a command, a first clock line carrying a command clock for controlling the command transfer, a data bus for transferring data and a second clock line carrying a data clock for controlling the data transfer.
- the detection section is provided in the master chip.
- the master chip further includes: a command production section for producing a command including as a part thereof the information produced by the detection section; and a command output section for outputting the command to the command bus based on the command clock.
- the slave chip includes: a clock input section for receiving the command clock from the first clock line; an input section for receiving the command from the command bus in accordance with the command clock; an extraction section for extracting the information included in the received command; a data output section for outputting data in the slave chip to the data bus in accordance with the data clock; and a clock output section for outputting the data clock to the second clock line.
- the at least one clock phase adjustment section receives the command clock and produces a data clock by adjusting a phase of the command clock based on the change in the state of the semiconductor integrated circuit system indicated by the information extracted by the extraction section.
- the command is transferred in a packet; and the command production section produces a command packet including the information and a chip ID.
- the at least one clock phase adjustment section comprises a plurality of delay units which are selectively used based on the change in the state of the semiconductor integrated circuit system.
- each of the plurality of slave chips comprises the detection section and the at least one clock phase adjustment section.
- the master chip and the plurality of slave chips are each connected to a command bus for transferring a command, a first clock line carrying a command clock for controlling the command transfer, a data bus for transferring data and a second clock line carrying a data clock for controlling the data transfer.
- Each of the plurality of slave chips further includes: a clock input section for receiving the command clock from the first clock line; an input section for receiving the command from the command bus in accordance with the command clock; a data output section for outputting data in the slave chip obtained based on the received command to the data bus in accordance with the data clock; and a clock output section for outputting the data clock to the second clock line.
- the at least one clock phase adjustment section produces the data clock by adjusting a phase of the command clock based on the change in the state of the semiconductor integrated circuit system indicated by the information provided by the detection section.
- the at least one clock phase adjustment section includes first and second clock phase adjustment sections. While one of the first clock phase adjustment section and the second clock phase adjustment section is performing phase adjustment in one operating cycle, the other one prepares for phase adjustment in a next operating cycle.
- a semiconductor integrated circuit operating in synchronization with a predetermined clock includes: a clock input section for receiving a command clock; a command input section for receiving a command in accordance with the command clock, the command including information indicating a change in a state which includes at least one of temperature and source voltage; an extraction section for extracting the information from the received command; at least one clock phase adjustment section for producing a data clock by adjusting a phase of the received command clock based on the change in the state indicated by the information extracted by the extraction section; a data output section for outputting data in the slave chip in accordance with the data clock; and a clock output section for outputting the data clock.
- the at least one clock phase adjustment section includes first and second clock phase adjustment sections. While one of the first clock phase adjustment section and the second clock phase adjustment section is performing phase adjustment in one operating cycle, the other one prepares for phase adjustment in a next operating cycle.
- a semiconductor integrated circuit operating in synchronization with a predetermined clock includes: a clock input section for inputting a reference clock; a synchronization section for producing an internal clock corresponding to a source voltage level, the synchronization section receiving the reference clock, outputting the internal clock in synchronization with the reference clock by changing the source voltage level, and outputting as a reference voltage signal a source voltage level which is determined by synchronizing the internal clock with the reference clock; a source voltage generation section for generating a supply voltage based on the reference voltage signal; a clock phase adjustment section for receiving the internal clock, and outputting an output control clock by adjusting a phase of the internal clock based on the source voltage; and a data output section for outputting data in the semiconductor integrated circuit in accordance with the output control clock.
- a frequency of the reference clock in an operating mode of the semiconductor integrated circuit is different from that in a stand-by mode of the semiconductor integrated circuit system.
- the frequency of the reference clock in the operating mode is greater than that in the stand-by mode.
- the source voltage generation section includes a first source voltage generation section used in an operating mode of the semiconductor integrated circuit and a second source voltage generation section used in a stand-by mode of the semiconductor integrated circuit.
- a semiconductor integrated circuit operating in synchronization with a predetermined clock includes: a first clock input section for inputting a reference clock; a second clock input section for inputting an adjustment clock; a synchronization section for producing an internal clock corresponding to a source voltage level, the synchronization section receiving the adjustment clock, synchronizing the internal clock with the adjustment clock by changing the source voltage level, and outputting as a reference voltage signal a source voltage level which is determined by the synchronization; a source voltage generation section for generating a source voltage based on the reference voltage signal; a clock phase adjustment section for receiving the reference clock, and outputting an output control clock by adjusting a phase of the reference clock based on the source voltage; and a data output section for outputting data in the semiconductor integrated circuit in accordance with the output control clock.
- the second clock input section produces the adjustment clock by dividing a frequency of the reference clock from the first clock input section.
- a method for driving a semiconductor integrated circuit system which has one master chip and a plurality of slave chips for performing data transfer under a control of a predetermined clock.
- the method includes the steps of: initializing a data transfer clock in each slave chip after power-up and before starting a read/write operation: detecting changes in temperature and source voltage so as to produce an information signal indicating the detection result; and adjusting a phase of the initialized data transfer clock in each slave chip based on the information signal.
- the invention described herein makes possible the advantages of: (1) providing a semiconductor integrated circuit system capable of stably operating at a high speed even when a semiconductor integrated circuit system has IC chips from various manufacturers, or when the circuit characteristics (e.g., the temperature dependency, the voltage dependency, etc.) vary among respective IC chips; (2) providing a semiconductor integrated circuit for use in such a semiconductor integrated circuit system; and (3) providing a method for driving such a semiconductor integrated circuit system.
- FIG. 1 is a block diagram schematically illustrating a semiconductor integrated circuit system of the present invention
- FIG. 2 is a block diagram schematically illustrating a semiconductor integrated circuit system according to Example 1 of the present invention
- FIG. 3 is a timing diagram illustrating a timing of data output according to Example 1 of the present invention.
- FIG. 4 is a timing diagram illustrating an exemplary timing for re-setting a clock phase adjustment circuit according to Example 1 of the present invention
- FIG. 5 is a diagram illustrating an example of a command packet according to Example 1 of the present invention.
- FIG. 6 is a timing diagram illustrating another exemplary timing for re-setting a clock phase adjustment circuit according to Example 1 of the present invention.
- FIG. 7 is a diagram illustrating an example of a configuration of a detection circuit according to Example 1 of the present invention.
- FIG. 8 is a diagram illustrating an example of a configuration of a command production circuit according to Example 1 of the present invention.
- FIGS. 9A and 9B are diagrams each illustrating an example of encoding by the command production circuit
- FIG. 10 is a diagram illustrating an example of a configuration of an extraction circuit according to Example 1 of the present invention.
- FIG. 11 is a diagram illustrating an example of a configuration of a clock phase adjustment circuit according to Example 1 of the present invention.
- FIG. 12 is a diagram illustrating another example of a configuration of a clock phase adjustment circuit according to Example 1 of the present invention.
- FIG. 13 is a diagram illustrating a still another example of a configuration of a clock phase adjustment circuit according to Example 1 of the present invention.
- FIG. 14 is a block diagram illustrating a semiconductor integrated circuit according to Example 2 of the present invention.
- FIG. 15 is a block diagram illustrating a semiconductor integrated circuit according to Example 2 of the present invention where a detection circuit is configured with a PLL;
- FIG. 16 is a diagram illustrating a waveform of an input clock according to Example 2 of the present invention.
- FIG. 17 is a diagram illustrating an example of a configuration of a power source circuit for a clock phase adjustment circuit used in an example of the present invention
- FIG. 18 is a diagram illustrating waveforms of an input clock and a frequency-divided clock
- FIG. 19 is a block diagram illustrating a semiconductor integrated circuit according to Example 2 of the present invention.
- FIG. 20 is a diagram illustrating waveforms of an input clock and a temperature/voltage adjustment clock.
- FIG. 1 is a block diagram schematically illustrating a semiconductor integrated circuit 100 of the present invention.
- the semiconductor integrated circuit 100 includes one master chip 1 and a plurality of slave chips 2 .
- Data processing e.g., a read, write or arithmetic operation
- the master chip 1 controls the master chip 1 .
- the resultant data DATA from the slave chip 2 is transferred under the control of a predetermined clock CLK.
- the semiconductor integrated circuit 100 includes a detection section for detecting a change in the state (e.g., the temperature, the source voltage, etc.) of the semiconductor integrated circuit 100 and for producing information indicating the detection result, and a clock phase adjustment section for adjusting the phase of the clock used for transferring data which is output from the slave chip 2 .
- the clock phase adjustment section receives information indicating the detection result from the detection section, and adjusts the phase of the clock based on this information.
- Such a detection section can be controlled by the master chip 1 .
- the detection section can be provided in the master chip 1 while the clock phase adjustment section can be provided in each slave chip 2 .
- the detection section may be provided within the master chip 1 , or may be provided externally to the master chip 1 and provide the detection result to the master chip 1 .
- the detection section may also be provided in the slave chip 2 .
- FIG. 2 is a block diagram illustrating a semiconductor integrated circuit system 110 according to Example 1 of the present invention.
- the semiconductor integrated circuit system 110 includes two slave chips 2 , namely, a first slave chip 2 a and a second slave chip 2 b.
- the master chip 1 and the first and second slave chips 2 a and 2 b are each connected to a command bus 3 for transferring a command, a command clock line 4 carrying a command clock CLK 1 for controlling command transfer, a data bus 5 for data transfer, and a data clock line 6 carrying a data clock CLK 2 for controlling data transfer.
- the master chip 1 includes a detection circuit 11 for detecting a change in a state (operating environment) of the semiconductor integrated circuit system 110 , a command production circuit 12 for producing a command which includes as a part of the command the information produced by the detection circuit 11 , and a command output circuit 13 for outputting the produced command to the command bus 3 based on the command clock CLK 1 .
- the source voltage and temperature are used as values for indicating the state of the semiconductor integrated circuit system 110 .
- the detection circuit 11 detects changes in the source voltage and temperature in the semiconductor integrated circuit system 110 , and produces information indicating the detection result.
- the command clock CLK 1 on the command clock line 4 is input to a command clock input circuit 14 of the master chip 1 and in turn is provided to the command output circuit 13 .
- Each of the slave chips 2 a and 2 b includes: a command clock input circuit 24 for receiving the command clock CLK 1 from the command clock line 4 ; a command input circuit 23 for receiving a command from the command bus 3 in accordance with the command clock CLK 1 ; an extraction circuit 21 for extracting, from the received command, information indicating changes in the source voltage and temperature; a clock phase adjustment circuit 22 for producing the data clock CLK 2 ; a data output circuit 25 for outputting data in the slave chip to the data bus 5 in accordance with the data clock CLK 2 ; and a data clock output circuit 26 for outputting the data clock CLK 2 to the data clock line 6 .
- the clock phase adjustment circuit 22 produces the data clock CLK 2 by receiving the command clock CLK 1 and adjusting the phase of the command clock CLK 1 based on the change in the state of the semiconductor integrated circuit system 110 indicated by the information extracted by the extraction circuit 21 .
- the master chip 1 outputs a command to the command bus 3 under the control of the command clock CLK 1 .
- Each of the slave chips 2 a and 2 b receives, at the command input circuit 23 , the command transferred via the command bus 3 in accordance with the timing of the command clock CLK 1 provided from the command clock line 4 to the command clock input circuit 24 .
- the operation of the slave chip is determined based on the command.
- the first and second slave chips 2 a and 2 b have different distances (bus lengths) to the master chip 1 . Therefore, the data output timing of each slave chip is adjusted by delaying the input command clock CLK 1 by the clock phase adjustment circuit 22 .
- the data clock CLK 2 for controlling data transfer is produced by delaying (or adjusting the phase of) the command clock CLK 1 .
- the slave chip 2 outputs data based on the data clock CLK 2 , so that data from one slave chip 2 and data from another arrive at the master chip 1 simultaneously.
- the data output circuit 25 of each slave chip 2 outputs data based on the data clock CLK 2 whose timing is adjusted in accordance with the distance from the slave chip 2 to the master chip 1 .
- the data clock CLK 2 used for the data output is simultaneously output from the data clock output circuit 26 to the data clock line 6 .
- the data and the data clock CLK 2 which determines the timing at which the data is received, can be made to arrive at the master chip 1 while maintaining an unshifted chronological relationship therebetween.
- Such an amount of delay in accordance with the bus length (distance to the master chip 1 ) of each slave chip 2 is set in the clock phase adjustment circuit 22 of the slave chip 2 at the initialization of the semiconductor integrated circuit system 110 (i.e., at power-up, and before starting a read/write operation).
- the semiconductor integrated circuit system 110 includes a plurality of slave chips 2
- the clock phase adjustment circuit 22 of one slave chip 2 has certain operating characteristics in connection with the system operating state (e.g., the temperature or source voltage) which are different from those of another slave chip 2 , it is necessary to re-set each clock phase adjustment circuit 22 in accordance with the change in the system operating state from that at the initialization.
- the detection circuit 11 for detecting changes in the source voltage and temperature is provided in the master chip 1 .
- the changes in the source voltage and temperature detected by the detection circuit 11 are provided to the command production circuit 12 as information indicating changes in the system operating state.
- the command production circuit 12 produces a command including information indicating such changes and provides the information to the command output circuit 13 .
- the command output circuit 13 outputs the command to the command bus 3 in accordance with the command clock CLK 1 which is provided from the command clock input circuit 14 .
- the output command is transferred via the command bus 3 to the first and second slave chips 2 a and 2 b.
- the command clock CLK 1 is carried by the command clock line 4 to each chip.
- the command clock CLK 1 on the command clock line 4 is received by the command clock input circuit 24 of each slave chip 2 .
- the command on the command bus 3 is received by the command input circuit 23 of each slave chip 2 which is controlled in accordance with the timing of the command clock CLK 1 provided by the command clock input circuit 24 .
- the received command is provided to the extraction circuit 21 .
- the extraction circuit 21 extracts information indicating changes in the source voltage and temperature contained in the command.
- the extracted information indicating changes in the source voltage and temperature is provided to the clock phase adjustment circuit 22 .
- the clock phase adjustment circuit 22 outputs the data clock CLK 2 whose phase is adjusted by re-setting the amount of delay of the command clock CLK 1 based on the change-related information.
- the data clock CLK 2 is provided to the data clock output circuit 26 .
- the data output circuit 25 outputs data in the slave chip 2 to the data bus 5 in accordance with the data clock CLK 2 whose phase is adjusted based on the changes in the system operating state.
- FIG. 3 schematically illustrates the timing of a read operation for reading data from a memory in the slave chip 2 , as an example of the operation of the semiconductor integrated circuit system 110 as illustrated in FIG. 2.
- the command includes the above-described change-related information and a reading address in the slave chip 2 .
- the command is sent in a packet in synchronization with the command clock CLK 1 .
- Data resulting from the execution of this command i.e., a read operation
- a predetermined arithmetic operation is executed in each slave chip 2 .
- FIG. 4 is a timing diagram illustrating an example of the operation of the semiconductor integrated circuit system 110 from initialization to a read/write operation.
- the chip initialization includes resetting register circuits in the chip, turning on the internal power source, and the like.
- setting of the clock phase adjustment circuit 22 of each slave chip 2 is performed. For example, an amount of delay is first set in the clock phase adjustment circuit 22 of the first slave chip 2 a (FIG. 2). Such setting is performed, as in a conventional SLDRAM, via data exchange between the master chip 1 (controller) and each slave chip 2 .
- the clock phase adjustment for the slave chip 2 a can be performed by comparing the command clock CLK 1 with the data clock CLK 2 which is input to the master chip 1 via the slave chip 2 a. After completing the phase adjustment for the slave chip 2 a, an amount of delay is set in a similar manner in the clock phase adjustment circuit 22 of the second slave chip 2 b.
- FIG. 2 illustrates an example where there are two slave chips 2 , the number of the slave chips 2 is not limited to two. When there are provided more slave chips 2 , the slave chips 2 an be successively set in a manner similar to that described above.
- a normal processing operation such as a read/write operation is performed.
- the clock phase adjustment circuit 22 of the slave chip 2 is re-set for each cycle of the read/write operation.
- the phase of the data clock CLK 2 in each slave chip 2 is re-adjusted in accordance with changes in the system operating state.
- the clock phase adjustment circuit 22 is re-set for each cycle of a read/write operation. Therefore, even in the case of abrupt changes in the state of the semiconductor integrated circuit system 110 (e.g., a drop in the source voltage), it is possible to quickly adapt the system to the new state, and thus realize accurate and stable operation of the system. Such an adjustment is particularly advantageous when running an application with a large power consumption, for example.
- FIG. 5 schematically illustrates an example of a structure of a command transferred in a packet via a command bus of 8 bits (C 0 to C 7 ).
- FIG. 5 illustrates a command packet including a command for performing a read/write operation.
- the first cycle of the command clock corresponds to chip ID information (ID 0 to ID 7 ), which designates the slave chip to which the command is provided.
- the four bits (C 0 to C 3 ) of the command bus in the second cycle are assigned to be the information indicating changes in the operating state of the semiconductor integrated circuit system 110 , thereby providing a command (TV 0 to TV 3 ) indicating information regarding changes in the temperature and source voltage.
- each cycle of the read/write operation after one slave chip 2 is designated, information indicating changes in the temperature and source voltage is sent, so as to reset the clock phase adjustment circuit 22 of the corresponding slave chip 2 before the read/write operation is performed.
- the remaining four bits (C 4 to C 7 ) of the command bus in the second cycle are assigned to be other information, such as, for example, row addresses (RA 0 to RA 3 ) of the slave chip 2 .
- FIG. 6 is a timing diagram illustrating another example of the operation of the semiconductor integrated circuit system 110 from initialization to a read/write operation.
- the initialization operation is the same as that illustrated in FIG. 4.
- the re-setting of the clock phase adjustment circuit 22 of each slave chip 2 is not performed for each cycle of the read/write operation, but is performed at every occurrence of a predetermined time period during the read/write operation.
- a command for resetting the clock phase adjustment circuit 22 of the slave chip 2 may be output at every occurrence of the predetermined time period.
- the re-setting of the clock phase adjustment circuit 22 may be performed for one slave chip 2 each time, or may be performed for all of the slave chips 2 at once.
- FIG. 7 illustrates an example of a configuration of the detection circuit 11 according to the present example.
- the detection circuit 11 includes a temperature detection circuit 11 a, a voltage detection circuit 11 b and a reference voltage generation circuit 11 c.
- the reference voltage generation circuit lic generates a predetermined reference voltage independently of the temperature and source voltage of the semiconductor integrated circuit system 110 .
- the reference voltage generation circuit 11 c can be configured based on a conventional technique. For example, the “REFERENCE VOLTAGE GENERATOR” described in U.S. Pat. No. 5,448,159 can be used.
- the temperature detection circuit 11 a includes a PLL therein, and utilizes the phenomenon that an output VCO of a voltage controlled oscillator included in the PLL varies as the temperature changes.
- changes in the temperature are detected by comparing the value VCO and each of the values VR 1 to VR 3 (obtained by subjecting the reference voltage V ref provided by the reference voltage generation circuit 11 c to voltage division using register elements 1 to 5 ), at comparison circuits L 1 to L 3 , and thereby determining the difference therebetween.
- the detection results are output from the comparison circuits L 1 to L 3 as temperature change detection signals T 1 to T 3 .
- the voltage detection circuit 11 b detects changes in the source voltage by comparing a voltage value V CMP (obtained by dividing a system source voltage V DD by resistor elements 6 and 7 ) and the reference voltage V ref (provided by the reference voltage generation circuit 11 c ) at comparison circuits R 1 to R 3 , and thereby determining the difference therebetween.
- the detection results are output from the comparison circuits R 1 to R 3 as source voltage detection signals V 1 to V 3 .
- the temperature change detection signals T 1 to T 3 and the source voltage detection signals V 1 to V 3 are digital signals, as will be described later.
- FIG. 8 illustrates an example of a configuration of the command production circuit 12 according to the present example.
- the command production circuit 12 includes a temperature-side command production circuit 12 a and a voltage-side command production circuit 12 b.
- the temperature-side command production circuit 12 a receives and encodes the temperature change detection signals T 1 to T 3 so as to output a 2-bit command (TV 0 and TV 1 ) of temperature change information.
- FIG. 9A illustrates an example of encoding by the temperature-side command production circuit 12 a. As illustrated in FIG. 9A, a temperature setting value is determined in accordance with the value of each bit (TV 0 and TV 1 ) of the command of temperature change information. In each slave chip 2 , the amount of delay for the clock phase adjustment circuit 22 is re-adjusted based on the temperature setting which is determined by this command.
- the voltage-side command production circuit 12 b receives and encodes the source voltage detection signals V 1 to V 3 so as to output a 2-bit command (TV 2 and TV 3 ) of voltage change information.
- FIG. 9B illustrates an example of encoding by the voltage-side command production circuit 12 b. As illustrated in FIG. 9B, a voltage setting value is determined in accordance with the value of each bit of the command of voltage change information (TV 2 and TV 3 ). In each slave chip 2 , the amount of delay for the clock phase adjustment circuit 22 is re-adjusted based on the voltage setting which is determined by this command.
- FIG. 10 illustrates a detailed circuit configuration of the extraction circuit 21 in each slave chip 2 of the semiconductor integrated circuit system 110 as illustrated in FIG. 2.
- the extraction circuit 21 includes a latch circuit 42 ( 42 a to 42 d ) for latching the command (TV 0 to TV 3 ) provided by the command input circuit 23 , and an information extraction section 43 ( 43 a to 43 p ) for extracting information indicating changes in the temperature and source voltage.
- the command TV 0 to TV 3 of change-related information indicating changes in the temperature and source voltage is provided from a command bus 41 (4 bits in the present example) in the extraction circuit 21 to the latch circuit 42 .
- the latch circuit 42 includes the latch sections 42 a to 42 d corresponding to the respective bits, and the latch sections 42 a to 42 d are controlled by a latch circuit control signal 51 .
- Outputs 52 a to 52 d respectively from the latch sections 42 a to 42 d and outputs 53 a to 53 d complementary thereto are provided to the information extraction section 43 .
- the information extraction section 43 decodes the latched 4-bit command TV 0 to TV 3 using the decoder sections 43 a to 43 p so as to output adjustment signals 54 a to 54 p which correspond to 16 different setting values provided in accordance with the changes in the temperature and source voltage.
- the adjustment signal 54 ( 54 a to 54 p ) obtained by the extraction circuit 21 is provided to the clock phase adjustment circuit 22 .
- the 4-bit command TV 0 to TV 3 carries information including a temperature change (2 bits) and a source voltage change (2 bits).
- a temperature change (2 bits)
- a source voltage change (2 bits).
- FIG. 11 is a diagram illustrating a detailed circuit configuration of the clock phase adjustment circuit 22 in each slave chip 2 of the semiconductor integrated circuit system 110 as illustrated in FIG. 2.
- the clock phase adjustment circuit 22 includes a delay amount setting circuit 61 , a clock signal input switching circuit 62 and a clock delay circuit 63 .
- the clock delay circuit 63 includes a plurality of delay circuits 63 a to 63 p.
- an amount of delay in accordance with the system operating condition such as the temperature and voltage is set.
- a reference amount of delay is set in the delay circuit 63 a so as to use the delay circuit 63 a as a delay circuit for a normal condition.
- the delay circuit 63 b may be used for a normal temperature/low voltage condition, the delay circuit 63 c for a normal temperature/high voltage, and the delay circuit 63 d for a high temperature/reference voltage condition, for example.
- 16 different delay amounts (respectively corresponding to the delay circuits 63 a to 63 p ) can be set corresponding to 16 different output signals 54 provided by the extraction circuit 21 .
- the adjustment signal 54 ( 54 a to 54 p ) output from the extraction circuit 21 is input to the clock signal input switching circuit 62 .
- an initialization signal provided to the slave chip 2 from the master chip 1 is input to the delay amount setting circuit 61 via a delay amount setting signal input terminal 60 .
- a predetermined amount of delay in accordance with the initialization signal is set (stored) in the delay amount setting circuit 61 .
- the clock phase adjustment circuit 22 delays, by a predetermined amount, a clock signal (command clock CLK 1 ) input from a clock input terminal 65 by using one of the delay circuits 63 a to 63 p (e.g., the delay circuit 63 a for a normal condition) selected in accordance with the predetermined amount of delay stored in the delay amount setting circuit 61 .
- the delayed command clock CLK 1 is output from a delayed clock output terminal 66 as a phase-adjusted clock signal (data clock CLK 2 ).
- the selection of one of the delay circuits 63 a to 63 p used in the clock delay circuit 63 is performed by the clock signal input switching circuit 62 .
- the clock signal input switching circuit 62 includes switching elements 62 a to 62 p and selects one of the delay circuits 63 a to 63 p in accordance with the adjustment signal 54 ( 54 a to 54 p ) so as to input the clock signal to the selected delay circuit.
- Each of the delay circuits 63 a to 63 p have respective delay amounts corresponding to the conditions (the temperature, the voltage, etc.) defined by the adjustment signal 54 .
- information indicating changes in the operating state of the semiconductor integrated circuit system 110 is provided from the master chip 1 to the slave chip 2 via the command VT 0 to VT 3 .
- the change-related information is extracted (decoded) from a command provided by the extraction circuit 21 , switching of the delay circuits 63 a to 63 p of the clock phase adjustment circuit 22 is performed based on the extracted information so as to re-set the amount of delay of the clock signal in accordance with changes in the condition.
- the clock signal input switching circuit 62 is provided before (i.e., on the input side of) the clock delay circuit 63 , so as to selectively use one of the delay circuits 63 a to 63 p.
- a switching circuit may be provided after the clock delay circuit 63 so as to selectively output a clock having a predetermined amount of delay on the output side of the clock delay circuit 63 .
- a switching circuit may also be provided on the output-side clock delay circuit 63 as well as on the input side thereof.
- FIG. 12 is a diagram illustrating another example of the configuration of the clock phase adjustment circuit 22 (namely, a clock phase adjustment circuit 22 ′) in each slave chip 2 of the semiconductor integrated circuit system 110 as illustrated in FIG. 2.
- the clock phase adjustment circuit 22 ′ includes a delay amount setting circuit 70 , the clock signal input switching circuit 62 , the outputside clock delay circuit 63 and an output-side clock path switching circuit 74 .
- the delay amount setting circuit 70 includes a count amount setting circuit 71 , a comparison circuit 72 and a counter circuit 73 .
- Each of the elements which are also provided in the above-described clock phase adjustment circuit 22 is provided with the same reference numeral, and will not be described in detail below.
- the operation of the clock phase adjustment circuit 22 ′ is basically the same as that of the above-described clock phase adjustment circuit 22 (FIG. 11).
- the clock phase adjustment circuit 22 ′ illustrated in FIG. 12 performs the setting of the delay time by controlling the number of times the input clock (command clock CLK 1 ) passes through the clock delay circuit 63 .
- the physical size of the clock delay circuit 63 can be reduced. The details will be described hereinafter.
- the delay amount setting circuit 70 sets (stores), in the count amount setting circuit 71 , a predetermined count value corresponding to an amount of delay to be set, in accordance with a delay amount setting signal provided from the master chip 1 to the delay amount setting signal input terminal 60 at initialization.
- the counter circuit 73 counts the number of clocks input to the counter circuit 73 .
- the comparison circuit 72 compares the count number of the counter circuit 73 with the count setting value of the count amount setting circuit 71 , and, if they match with each other, outputs a predetermined clock path switching signal 75 to the output-side clock path switching circuit 74 .
- the output-side clock path switching circuit 74 under the control of the clock path switching signal 75 , outputs the data clock CLK 2 from the delayed clock output terminal 66 only when the count number of the counter circuit 73 matches with the count setting value set in the count amount setting circuit 71 .
- the selection of one of the delay circuits 63 a to 63 p used in the clock delay circuit 63 is performed by the clock signal input switching circuit 62 , as in the above-described example. After the predetermined count setting value has been reached, the output of the selected one of the delay circuits 63 a to 63 p is output via the output-side clock path switching circuit 74 as the data clock CLK 2 . Due to such a structure, it is possible to reduce the number of stages in the clock delay circuit 63 , thereby reducing the circuit scale of the clock delay circuit 63 .
- FIG. 13 is a diagram illustrating a configuration of a clock phase adjustment circuit 22 ′′.
- the clock phase adjustment circuit 22 ′′ includes a first clock phase adjustment unit 22 a, a second clock phase adjustment unit 22 b and an output switching circuit 78 .
- the configuration and the operation of each of the first and second clock phase adjustment units 22 a and 22 b is the same as those of the above-described clock phase adjustment circuit 22 (FIG. 11).
- Each of the elements which are also provided in the above-described clock phase adjustment circuit 22 is provided with the same reference numeral, and will not be described in detail below.
- an initialization signal for setting (storing) a predetermined amount of delay at initialization is provided to a first delay amount setting signal input terminal 60 a of the first clock phase adjustment unit 22 a and to a second delay amount setting signal input terminal 60 b of the second clock phase adjustment unit 22 b.
- the command clock CLK 1 is provided to a first clock input terminal 65 a of the first clock phase adjustment unit 22 a and to the second clock input terminal 65 b of the second clock phase adjustment unit 22 b.
- the internal operation of each of the first and second clock phase adjustment units 22 a and 22 b is the same as that of the above-described clock phase adjustment circuit 22 .
- the clock phase adjustment circuit 22 ′′ includes the two clock phase adjustment units 22 a and 22 b which are used alternately.
- the clocks (data clocks CLK 2 ) output from the first and second clock phase adjustment units 22 a and 22 b are alternately output by the output switching circuit 78 .
- the first and second clock phase adjustment units 22 a and 22 b are alternately used, so that while the delay amount of one of the units is being adjusted, the other unit can be used.
- the two clock phase adjustment units do not necessarily have to be used alternately, but one of the clock phase adjustment units may continuously output the data clock CLK 2 for a predetermined period of time. Due to the configuration of the clock phase adjustment circuit 22 ′′, it is possible to prevent a clock delaying operation from being interrupted when re-setting a clock delay amount. Thus, while the delay amount of one of the clock phase adjustment units is being set, the other unit can be operated, so that it is possible to perform the delay operation (phase adjustment operation) in an uninterrupted manner.
- each slave chip (semiconductor integrated circuit) is provided with a circuit for detecting changes in the operating environment of the system.
- the semiconductor integrated circuit of the present example includes a circuit for adjusting the phase of the data output clock which determines the timing of data output in accordance with the positional relationship with respect to the master chip, and further includes a circuit for preventing the operation of the data output clock phase adjustment circuit from changing due to changes in the operating environment of the system (e.g., the temperature, the source voltage, etc.).
- FIG. 14 is a block diagram schematically illustrating a configuration of a semiconductor integrated circuit (slave chip) 200 according to Example 2 of the present invention.
- the semiconductor integrated circuit 200 includes a clock input circuit 201 for receiving an externally-fed clock, a detection circuit 202 for detecting changes in the operating environment of the system, a power source circuit 203 for an output clock phase adjustment circuit (hereinafter, referred to simply as the “power source circuit 203 ”), an output clock phase adjustment circuit 204 , a clock output circuit 205 and a data output circuit 206 .
- the clock CLK 1 which is provided from the outside of the semiconductor integrated circuit 200 (e.g., from the master chip) is input to the clock input circuit 201 of the semiconductor integrated circuit 200 .
- the clock input circuit 201 outputs the input clock CLK 1 as a reference clock 210 to the output clock phase adjustment circuit 204 .
- the detection circuit 202 detects changes in the temperature and voltage, and outputs to the power source circuit 203 a reference voltage 212 , which is determined based on the changes.
- the power source circuit 203 outputs a power source potential 213 for a clock phase adjustment circuit in accordance with the input reference voltage 212 .
- the output clock phase adjustment circuit 204 shifts, by a predetermined value (amount of delay), the phase of the reference clock 210 provided by the clock input circuit 201 in accordance with the power source potential 213 provided by the power source circuit 203 , and outputs the phase-shifted clock as an output control clock 214 to the clock output circuit 205 .
- the clock output circuit 205 outputs the output control clock 214 to the data output circuit 206 while also outputting the output control clock 214 , as a strobe signal (clock CLK 2 ) for data output by the data output circuit 206 , simultaneously with the output data, to the outside of the semiconductor integrated circuit 200 .
- the detection circuit 202 can be configured with a PLL circuit, for example.
- a PLL circuit for example.
- an example where the detection circuit 202 is a PLL circuit will be described in greater detail.
- FIG. 15 illustrates a configuration of the semiconductor integrated circuit 200 where the detection circuit 202 is a PLL circuit.
- the clock CLK 1 provided from the outside of the semiconductor integrated circuit 200 (e.g., from the master chip) is input to the clock input circuit 201 of the semiconductor integrated circuit 200 .
- the clock input circuit 201 outputs the input clock CLK 1 as a reference clock 210 ′ to the detection circuit 202 .
- the detection circuit (PLL) 202 includes a VCO for producing an internal clock, and varies the potential of the VCO so as to synchronize an internal clock 211 with the input reference clock 210 ′′.
- the detection circuit 202 provides, as the reference voltage 212 , the potential of the VCO at the time when the internal clock 211 is synchronized with the reference clock 210 ′ to the power source circuit 203 .
- the power source circuit 203 outputs the power source potential 213 for a clock phase adjustment circuit based on the input reference voltage 212 .
- the detection circuit 202 provides the internal clock 211 synchronized with the reference clock 210 ′ (i.e., the phase of the reference clock 210 ′ is equal to that of the internal clock 211 ) to the output clock phase adjustment circuit 204 .
- the output clock phase adjustment circuit 204 shifts, by a predetermined value (amount of delay), the input internal clock 211 , and outputs the shifted clock as the output control clock 214 to the clock output circuit 205 .
- the clock output circuit 205 outputs the output control clock 214 to the data output circuit 206 .
- the data output circuit 206 outputs data in the semiconductor integrated circuit 200 in accordance with the provided output control clock 214 .
- the data in the semiconductor integrated circuit 200 is, for example, data read out from a memory, the result of a predetermined arithmetic operation, or the like.
- the clock output circuit 205 outputs the output control clock 214 as a strobe signal for the output data.
- the operation of the output clock phase adjustment circuit 204 changes accordingly.
- the power source circuit 203 is employed in order to prevent such a change in the operation of the output clock phase adjustment circuit 204 .
- the detection circuit 202 varies the potential of the VCO in the detection circuit 202 in order to match the phase of the externally-input reference clock 210 ′ with that of the input internal clock 211 .
- the power source circuit 203 uses the potential of the VCO (the reference voltage 212 ) as the reference voltage for the operation thereof, the power source potential 213 for a clock phase adjustment circuit, which is output by the power source circuit 203 , changes in accordance with the change in the reference voltage 212 . Due to the power source potential 213 which changes as described above, the change in the operation of the output clock phase adjustment circuit 204 is suppressed.
- FIG. 16 illustrates a waveform of a clock input to the semiconductor integrated circuit 200 .
- the frequency of the input clock is lower in a stand-by mode than in an operating mode.
- FIG. 17 illustrates an example of a circuit configuration of the power source circuit 203 .
- the power source circuit 203 generates the source voltage 213 in accordance with the change in the reference voltage 212 .
- the power source circuit 203 may be configured to include two power source circuits; one for an operating mode and another for a stand-by mode.
- the power source circuit for an operating mode may be one which has a high response speed and a large power consumption.
- the power source circuit for a stand-by mode may be one which has a low response speed and a small power consumption.
- a clock frequency divider may be provided.
- the reference clock 210 ′ output by the clock input circuit may be provided intact to the output clock phase adjustment circuit 204 , while providing it to the detection circuit 202 as a frequency-divided clock after dividing the frequency thereof using the frequency division circuit.
- FIG. 18 illustrates timing diagrams for the input clock and the frequency-divided clock. As illustrated in FIG. 18, the frequency of the divided clock is lower than that of the input clock, so that voltage setting may be performed in the power source circuit 203 at a low frequency, thereby reducing the power consumption accordingly.
- FIG. 19 is a block diagram illustrating a configuration of another semiconductor integrated circuit 300 of the present example.
- the semiconductor integrated circuit 300 includes the clock input circuit 201 , as a first clock input circuit, and a second clock input circuit 301 .
- the configuration of the semiconductor integrated circuit 300 is the same as that of the semiconductor integrated circuit 200 as illustrated in FIG. 15, and like components are provided with like reference numerals and will not described in detail.
- the clock CLK 1 provided by the master chip, or the like, is input to the first clock input circuit 201 .
- the clock CLK 1 input to the first clock input circuit 201 is provided to the output clock phase adjustment circuit 204 as the reference clock 210 .
- the second clock input circuit 301 is a temperature/voltage adjustment clock input circuit, to which a clock CLK 3 is input.
- the clock CLK 3 is used for adjusting the phase of the clock as the operating environment (e.g., the temperature, the voltage, etc.) changes.
- FIG. 20 is a timing diagrams for the input clock CLK 1 and the temperature/voltage adjustment clock CLK 3 used in the semiconductor integrated circuit 300 .
- the frequency of the temperature/voltage adjustment clock CLK 3 is lower than that of the input clock CLK 1 . Therefore, voltage setting may be performed in the power source circuit 203 at a low frequency, thereby reducing the power consumption accordingly.
- the clock phase adjustment circuit of each slave chip can be re-set based on information output by the detection circuit for detecting changes in the operating environment (e.g., the temperature, the source voltage, etc.). Therefore, the clock phase adjustment circuit of each slave chip can be stably operated even when the operating environment changes.
- a semiconductor integrated circuit system capable of stably operating at a high speed even when a semiconductor integrated circuit system has IC chips from various manufacturers, or when the circuit characteristics (e.g., the temperature dependency, the voltage dependency, etc.) vary among respective IC chips; a semiconductor integrated circuit for use in such a semiconductor integrated circuit system; and a method for driving such a semiconductor integrated circuit system.
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Abstract
Description
- 1. Field of the Invention
- The present invention relates to a semiconductor integrated circuit system, a semiconductor integrated circuit and a method for driving a semiconductor integrated circuit system. More particularly, the present invention relates to a semiconductor integrated circuit system for high-speed data transfer in synchronization with a clock, a method for driving such a semiconductor integrated circuit system, and a semiconductor integrated circuit for use in such a semiconductor integrated circuit system.
- 2. Description of the Related Art
- In recent years, a new line of products has been developed for use in multimedia applications. One major feature of a multimedia application is the capability of handling motion pictures as well as characters, still images and sounds. Motion picture processing involves a huge amount of data, thereby requiring a high data transfer rate. One way to realize such a high data transfer rate is to increase a bus width of a data bus so as to transfer a large amount of data. However, when the bus width of a data bus is increased, the scale of the system is adversely increased. In view of this, it has been proposed to increase the data transfer rate (clock frequency) without increasing the bus width of a data bus so as to provide a semiconductor integrated circuit system capable of transferring a large amount of data at a very high speed.
- For example, a system using SyncLink DRAM, which inputs/outputs data at the dual edges of the clock, has been proposed and is described in Draft Standard for A High-Speed Memory Interface (SyncLink)-Draft 0.99 IEEE P1596.7-199X or “RAMBUS; PRODUCT CATALOG”. In such a semiconductor integrated circuit system, when the clock speed is increased in order to realize a high-speed data transfer, problems occur such as a clock skew or a skew between chips, due to the difference between the distance (bus length) from one slave chip to the master chip and the distance from another slave chip to the master chip. In view of this, in the above-described SyncLink system, the slave chips are each provided with a circuit for delaying (or adjusting the phase of) the data output clock for controlling the timing of data output based on the positional relationship with (or the bus length to) the master chip, as illustrated in Draft 0.99 IEEE P1596.7-199X, P.43, FIG. 36, for example.
- The distance from each slave chip to the master chip is detected at initialization of the system, so that a predetermined amount of delay in accordance with the distance is set in a circuit for adjusting the phase of the clock (hereinafter, referred to simply as the “clock phase adjustment circuit”) in the slave chip. The phase of the data output clock of each slave chip is adjusted as described above, so that the master chip can receive data from respective slave chips simultaneously, whereby it is possible to stably perform high-speed data transfer.
- However, such a conventional integrated circuit system as described above may include IC chips (semiconductor integrated circuits) which are not all from the same manufacturer. Among IC chips from different manufacturers, the characteristics (e.g., the temperature dependency or source voltage dependency) of the data output clock phase adjustment circuit provided in one IC chip may differ from those of another IC chip. The inventors of the present invention found that such difference in the characteristics of the data output clock phase adjustment circuit among the IC chips is particularly problematic in systems for high-speed data transfer such as those operating at a clock frequency of 200 MHz or higher. Such a change in the temperature or source voltage in a semiconductor integrated circuit system can easily occur, for example, due to the increasing temperature during use or when running an application with a large power consumption.
- Thus, when a semiconductor integrated circuit system has IC chips from various manufacturers, even if a proper amount of delay is set, at system initialization, for the clock phase adjustment circuit of each IC chip in accordance with the bus length thereof, when an operating condition of the system such as the temperature or source voltage thereof changes from that at initialization, the amount of delay of each IC chip shifts from the proper value. Since the shift in the amount of delay may vary among the IC chips depending upon the characteristics (e.g., the temperature dependency, the voltage dependency, etc.) of the clock phase adjustment circuits of the respective IC chips, the amount of delay of each IC chip gradually becomes mismatched with another as the operation conditions of the system change. Then, the clock skew among the IC chips cannot be compensated for, whereby the stable operation of the system may not be ensured.
- Moreover, even if the manufacturers make an agreement on standardizing those characteristics such as the temperature dependency or voltage dependency of a transistor, for example, it is difficult for the manufacturers to standardize such device characteristics over a wide range of temperature or voltage (e.g., to standardize the temperature dependency over a range of −100° C. to +100° C.). Therefore, such an agreement is not realistic.
- Furthermore, even when the system is provided with IC chips from one manufacturer, the IC chips do not always have the same circuit characteristics due to possible variation among different lots.
- According to one aspect of this invention, a semiconductor integrated circuit system, having one master chip and a plurality of slave chips, for performing data transfer under a control of a predetermined clock is provided. The system includes: a detection section for detecting a change in a state of the semiconductor integrated circuit system and for producing information indicating the detection result, the state including at least one of temperature and source voltage; and at least one clock phase adjustment section for receiving the information and for adjusting a phase of a clock used in transferring data output by the slave chip based on the information.
- In one embodiment of the invention, the detection section is controlled by the master chip, and the at least one clock phase adjustment section is included in the slave chip.
- In one embodiment of the invention, the master chip and the plurality of slave chips are each connected to a command bus for transferring a command, a first clock line carrying a command clock for controlling the command transfer, a data bus for transferring data and a second clock line carrying a data clock for controlling the data transfer. The detection section is provided in the master chip. The master chip further includes: a command production section for producing a command including as a part thereof the information produced by the detection section; and a command output section for outputting the command to the command bus based on the command clock. The slave chip includes: a clock input section for receiving the command clock from the first clock line; an input section for receiving the command from the command bus in accordance with the command clock; an extraction section for extracting the information included in the received command; a data output section for outputting data in the slave chip to the data bus in accordance with the data clock; and a clock output section for outputting the data clock to the second clock line. The at least one clock phase adjustment section receives the command clock and produces a data clock by adjusting a phase of the command clock based on the change in the state of the semiconductor integrated circuit system indicated by the information extracted by the extraction section.
- In one embodiment of the invention, the command is transferred in a packet; and the command production section produces a command packet including the information and a chip ID.
- In one embodiment of the invention, the at least one clock phase adjustment section comprises a plurality of delay units which are selectively used based on the change in the state of the semiconductor integrated circuit system.
- In one embodiment of the invention, each of the plurality of slave chips comprises the detection section and the at least one clock phase adjustment section.
- In one embodiment of the invention, the master chip and the plurality of slave chips are each connected to a command bus for transferring a command, a first clock line carrying a command clock for controlling the command transfer, a data bus for transferring data and a second clock line carrying a data clock for controlling the data transfer. Each of the plurality of slave chips further includes: a clock input section for receiving the command clock from the first clock line; an input section for receiving the command from the command bus in accordance with the command clock; a data output section for outputting data in the slave chip obtained based on the received command to the data bus in accordance with the data clock; and a clock output section for outputting the data clock to the second clock line. The at least one clock phase adjustment section produces the data clock by adjusting a phase of the command clock based on the change in the state of the semiconductor integrated circuit system indicated by the information provided by the detection section.
- In one embodiment of the invention, the at least one clock phase adjustment section includes first and second clock phase adjustment sections. While one of the first clock phase adjustment section and the second clock phase adjustment section is performing phase adjustment in one operating cycle, the other one prepares for phase adjustment in a next operating cycle.
- According to another aspect of this invention, a semiconductor integrated circuit operating in synchronization with a predetermined clock is provided. The semiconductor integrated circuit includes: a clock input section for receiving a command clock; a command input section for receiving a command in accordance with the command clock, the command including information indicating a change in a state which includes at least one of temperature and source voltage; an extraction section for extracting the information from the received command; at least one clock phase adjustment section for producing a data clock by adjusting a phase of the received command clock based on the change in the state indicated by the information extracted by the extraction section; a data output section for outputting data in the slave chip in accordance with the data clock; and a clock output section for outputting the data clock.
- In one embodiment of the invention, the at least one clock phase adjustment section includes first and second clock phase adjustment sections. While one of the first clock phase adjustment section and the second clock phase adjustment section is performing phase adjustment in one operating cycle, the other one prepares for phase adjustment in a next operating cycle.
- According to still another aspect of this invention, a semiconductor integrated circuit operating in synchronization with a predetermined clock is provided. The semiconductor integrated circuit includes: a clock input section for inputting a reference clock; a synchronization section for producing an internal clock corresponding to a source voltage level, the synchronization section receiving the reference clock, outputting the internal clock in synchronization with the reference clock by changing the source voltage level, and outputting as a reference voltage signal a source voltage level which is determined by synchronizing the internal clock with the reference clock; a source voltage generation section for generating a supply voltage based on the reference voltage signal; a clock phase adjustment section for receiving the internal clock, and outputting an output control clock by adjusting a phase of the internal clock based on the source voltage; and a data output section for outputting data in the semiconductor integrated circuit in accordance with the output control clock.
- In one embodiment of the invention, a frequency of the reference clock in an operating mode of the semiconductor integrated circuit is different from that in a stand-by mode of the semiconductor integrated circuit system.
- In one embodiment of the invention, the frequency of the reference clock in the operating mode is greater than that in the stand-by mode.
- In one embodiment of the invention, the source voltage generation section includes a first source voltage generation section used in an operating mode of the semiconductor integrated circuit and a second source voltage generation section used in a stand-by mode of the semiconductor integrated circuit.
- According to still another aspect of this invention, a semiconductor integrated circuit operating in synchronization with a predetermined clock is provided. The semiconductor integrated circuit includes: a first clock input section for inputting a reference clock; a second clock input section for inputting an adjustment clock; a synchronization section for producing an internal clock corresponding to a source voltage level, the synchronization section receiving the adjustment clock, synchronizing the internal clock with the adjustment clock by changing the source voltage level, and outputting as a reference voltage signal a source voltage level which is determined by the synchronization; a source voltage generation section for generating a source voltage based on the reference voltage signal; a clock phase adjustment section for receiving the reference clock, and outputting an output control clock by adjusting a phase of the reference clock based on the source voltage; and a data output section for outputting data in the semiconductor integrated circuit in accordance with the output control clock.
- In one embodiment of the invention, the second clock input section produces the adjustment clock by dividing a frequency of the reference clock from the first clock input section.
- According to still another aspect of this invention, a method for driving a semiconductor integrated circuit system which has one master chip and a plurality of slave chips for performing data transfer under a control of a predetermined clock is provided. The method includes the steps of: initializing a data transfer clock in each slave chip after power-up and before starting a read/write operation: detecting changes in temperature and source voltage so as to produce an information signal indicating the detection result; and adjusting a phase of the initialized data transfer clock in each slave chip based on the information signal.
- Thus, the invention described herein makes possible the advantages of: (1) providing a semiconductor integrated circuit system capable of stably operating at a high speed even when a semiconductor integrated circuit system has IC chips from various manufacturers, or when the circuit characteristics (e.g., the temperature dependency, the voltage dependency, etc.) vary among respective IC chips; (2) providing a semiconductor integrated circuit for use in such a semiconductor integrated circuit system; and (3) providing a method for driving such a semiconductor integrated circuit system.
- These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.
- FIG. 1 is a block diagram schematically illustrating a semiconductor integrated circuit system of the present invention;
- FIG. 2 is a block diagram schematically illustrating a semiconductor integrated circuit system according to Example 1 of the present invention;
- FIG. 3 is a timing diagram illustrating a timing of data output according to Example 1 of the present invention;
- FIG. 4 is a timing diagram illustrating an exemplary timing for re-setting a clock phase adjustment circuit according to Example 1 of the present invention;
- FIG. 5 is a diagram illustrating an example of a command packet according to Example 1 of the present invention;
- FIG. 6 is a timing diagram illustrating another exemplary timing for re-setting a clock phase adjustment circuit according to Example 1 of the present invention;
- FIG. 7 is a diagram illustrating an example of a configuration of a detection circuit according to Example 1 of the present invention;
- FIG. 8 is a diagram illustrating an example of a configuration of a command production circuit according to Example 1 of the present invention;
- FIGS. 9A and 9B are diagrams each illustrating an example of encoding by the command production circuit;
- FIG. 10 is a diagram illustrating an example of a configuration of an extraction circuit according to Example 1 of the present invention;
- FIG. 11 is a diagram illustrating an example of a configuration of a clock phase adjustment circuit according to Example 1 of the present invention;
- FIG. 12 is a diagram illustrating another example of a configuration of a clock phase adjustment circuit according to Example 1 of the present invention;
- FIG. 13 is a diagram illustrating a still another example of a configuration of a clock phase adjustment circuit according to Example 1 of the present invention;
- FIG. 14 is a block diagram illustrating a semiconductor integrated circuit according to Example 2 of the present invention;
- FIG. 15 is a block diagram illustrating a semiconductor integrated circuit according to Example 2 of the present invention where a detection circuit is configured with a PLL;
- FIG. 16 is a diagram illustrating a waveform of an input clock according to Example 2 of the present invention;
- FIG. 17 is a diagram illustrating an example of a configuration of a power source circuit for a clock phase adjustment circuit used in an example of the present invention;
- FIG. 18 is a diagram illustrating waveforms of an input clock and a frequency-divided clock;
- FIG. 19 is a block diagram illustrating a semiconductor integrated circuit according to Example 2 of the present invention; and
- FIG. 20 is a diagram illustrating waveforms of an input clock and a temperature/voltage adjustment clock.
- FIG. 1 is a block diagram schematically illustrating a semiconductor integrated
circuit 100 of the present invention. As illustrated in FIG. 1, the semiconductor integratedcircuit 100 includes onemaster chip 1 and a plurality of slave chips 2. Data processing (e.g., a read, write or arithmetic operation) is performed in eachslave chip 2 under the control of themaster chip 1, and the resultant data DATA from theslave chip 2 is transferred under the control of a predetermined clock CLK. The semiconductor integratedcircuit 100 includes a detection section for detecting a change in the state (e.g., the temperature, the source voltage, etc.) of the semiconductor integratedcircuit 100 and for producing information indicating the detection result, and a clock phase adjustment section for adjusting the phase of the clock used for transferring data which is output from theslave chip 2. The clock phase adjustment section receives information indicating the detection result from the detection section, and adjusts the phase of the clock based on this information. - Such a detection section can be controlled by the
master chip 1. For example, the detection section can be provided in themaster chip 1 while the clock phase adjustment section can be provided in eachslave chip 2. The detection section may be provided within themaster chip 1, or may be provided externally to themaster chip 1 and provide the detection result to themaster chip 1. Alternatively, the detection section may also be provided in theslave chip 2. - Hereinafter, examples of the present invention will be described in greater detail with reference to the accompanying drawings.
- FIG. 2 is a block diagram illustrating a semiconductor integrated
circuit system 110 according to Example 1 of the present invention. In the present example, the semiconductor integratedcircuit system 110 includes twoslave chips 2, namely, afirst slave chip 2 a and asecond slave chip 2 b. Themaster chip 1 and the first andsecond slave chips command bus 3 for transferring a command, acommand clock line 4 carrying a command clock CLK1 for controlling command transfer, adata bus 5 for data transfer, and adata clock line 6 carrying a data clock CLK2 for controlling data transfer. - As illustrated in FIG. 2, the
master chip 1 includes adetection circuit 11 for detecting a change in a state (operating environment) of the semiconductor integratedcircuit system 110, acommand production circuit 12 for producing a command which includes as a part of the command the information produced by thedetection circuit 11, and acommand output circuit 13 for outputting the produced command to thecommand bus 3 based on the command clock CLK1. - According to the present example, the source voltage and temperature are used as values for indicating the state of the semiconductor integrated
circuit system 110. Thedetection circuit 11 detects changes in the source voltage and temperature in the semiconductor integratedcircuit system 110, and produces information indicating the detection result. Moreover, the command clock CLK1 on thecommand clock line 4 is input to a command clock input circuit 14 of themaster chip 1 and in turn is provided to thecommand output circuit 13. - Each of the
slave chips clock input circuit 24 for receiving the command clock CLK1 from thecommand clock line 4; acommand input circuit 23 for receiving a command from thecommand bus 3 in accordance with the command clock CLK1; anextraction circuit 21 for extracting, from the received command, information indicating changes in the source voltage and temperature; a clockphase adjustment circuit 22 for producing the data clock CLK2; adata output circuit 25 for outputting data in the slave chip to thedata bus 5 in accordance with the data clock CLK2; and a dataclock output circuit 26 for outputting the data clock CLK2 to thedata clock line 6. The clockphase adjustment circuit 22 produces the data clock CLK2 by receiving the command clock CLK1 and adjusting the phase of the command clock CLK1 based on the change in the state of the semiconductor integratedcircuit system 110 indicated by the information extracted by theextraction circuit 21. - Next, the operation of the
master chip 1 and the slave chips 2 (2 a and 2 b) of the semiconductor integratedcircuit system 110 will be described in detail. - As illustrated in FIG. 2, the
master chip 1 outputs a command to thecommand bus 3 under the control of the command clock CLK1. Each of theslave chips command input circuit 23, the command transferred via thecommand bus 3 in accordance with the timing of the command clock CLK1 provided from thecommand clock line 4 to the commandclock input circuit 24. The operation of the slave chip is determined based on the command. - The first and
second slave chips master chip 1. Therefore, the data output timing of each slave chip is adjusted by delaying the input command clock CLK1 by the clockphase adjustment circuit 22. In other words, the data clock CLK2 for controlling data transfer is produced by delaying (or adjusting the phase of) the command clock CLK1. Theslave chip 2 outputs data based on the data clock CLK2, so that data from oneslave chip 2 and data from another arrive at themaster chip 1 simultaneously. Thus, thedata output circuit 25 of eachslave chip 2 outputs data based on the data clock CLK2 whose timing is adjusted in accordance with the distance from theslave chip 2 to themaster chip 1. Moreover, while data is output from thedata output circuit 25 to thedata bus 5, the data clock CLK2 used for the data output is simultaneously output from the dataclock output circuit 26 to thedata clock line 6. Thus, the data and the data clock CLK2, which determines the timing at which the data is received, can be made to arrive at themaster chip 1 while maintaining an unshifted chronological relationship therebetween. - Such an amount of delay in accordance with the bus length (distance to the master chip1) of each
slave chip 2 is set in the clockphase adjustment circuit 22 of theslave chip 2 at the initialization of the semiconductor integrated circuit system 110 (i.e., at power-up, and before starting a read/write operation). - However, when the semiconductor integrated
circuit system 110 includes a plurality ofslave chips 2, and the clockphase adjustment circuit 22 of oneslave chip 2 has certain operating characteristics in connection with the system operating state (e.g., the temperature or source voltage) which are different from those of anotherslave chip 2, it is necessary to re-set each clockphase adjustment circuit 22 in accordance with the change in the system operating state from that at the initialization. - In the present example, the
detection circuit 11 for detecting changes in the source voltage and temperature is provided in themaster chip 1. The changes in the source voltage and temperature detected by thedetection circuit 11 are provided to thecommand production circuit 12 as information indicating changes in the system operating state. As will be described later, thecommand production circuit 12 produces a command including information indicating such changes and provides the information to thecommand output circuit 13. Thecommand output circuit 13 outputs the command to thecommand bus 3 in accordance with the command clock CLK1 which is provided from the command clock input circuit 14. The output command is transferred via thecommand bus 3 to the first andsecond slave chips command clock line 4 to each chip. - The command clock CLK1 on the
command clock line 4 is received by the commandclock input circuit 24 of eachslave chip 2. The command on thecommand bus 3 is received by thecommand input circuit 23 of eachslave chip 2 which is controlled in accordance with the timing of the command clock CLK1 provided by the commandclock input circuit 24. The received command is provided to theextraction circuit 21. Theextraction circuit 21 extracts information indicating changes in the source voltage and temperature contained in the command. The extracted information indicating changes in the source voltage and temperature is provided to the clockphase adjustment circuit 22. The clockphase adjustment circuit 22 outputs the data clock CLK2 whose phase is adjusted by re-setting the amount of delay of the command clock CLK1 based on the change-related information. The data clock CLK2 is provided to the dataclock output circuit 26. Thedata output circuit 25 outputs data in theslave chip 2 to thedata bus 5 in accordance with the data clock CLK2 whose phase is adjusted based on the changes in the system operating state. - FIG. 3 schematically illustrates the timing of a read operation for reading data from a memory in the
slave chip 2, as an example of the operation of the semiconductor integratedcircuit system 110 as illustrated in FIG. 2. In this example, the command includes the above-described change-related information and a reading address in theslave chip 2. As illustrated in FIG. 3, the command is sent in a packet in synchronization with the command clock CLK1. Data resulting from the execution of this command (i.e., a read operation) is obtained after a predetermined time required for executing the command. The above similarly applies to the case where a predetermined arithmetic operation is executed in eachslave chip 2. - FIG. 4 is a timing diagram illustrating an example of the operation of the semiconductor integrated
circuit system 110 from initialization to a read/write operation. At system initialization, all of the chips are first initialized. For example, the chip initialization includes resetting register circuits in the chip, turning on the internal power source, and the like. After initializing all chips, setting of the clockphase adjustment circuit 22 of eachslave chip 2 is performed. For example, an amount of delay is first set in the clockphase adjustment circuit 22 of thefirst slave chip 2 a (FIG. 2). Such setting is performed, as in a conventional SLDRAM, via data exchange between the master chip 1 (controller) and eachslave chip 2. For example, the clock phase adjustment for theslave chip 2 a can be performed by comparing the command clock CLK1 with the data clock CLK2 which is input to themaster chip 1 via theslave chip 2 a. After completing the phase adjustment for theslave chip 2 a, an amount of delay is set in a similar manner in the clockphase adjustment circuit 22 of thesecond slave chip 2 b. Although FIG. 2 illustrates an example where there are twoslave chips 2, the number of theslave chips 2 is not limited to two. When there are providedmore slave chips 2, theslave chips 2 an be successively set in a manner similar to that described above. - After completing the initialization for each chip, a normal processing operation such as a read/write operation is performed. After a read/write operation is started, the clock
phase adjustment circuit 22 of theslave chip 2 is re-set for each cycle of the read/write operation. Thus, each time a read/write operation is performed, the phase of the data clock CLK2 in eachslave chip 2 is re-adjusted in accordance with changes in the system operating state. - As described above, the clock
phase adjustment circuit 22 is re-set for each cycle of a read/write operation. Therefore, even in the case of abrupt changes in the state of the semiconductor integrated circuit system 110 (e.g., a drop in the source voltage), it is possible to quickly adapt the system to the new state, and thus realize accurate and stable operation of the system. Such an adjustment is particularly advantageous when running an application with a large power consumption, for example. - FIG. 5 schematically illustrates an example of a structure of a command transferred in a packet via a command bus of 8 bits (C0 to C7). FIG. 5 illustrates a command packet including a command for performing a read/write operation. As illustrated in FIG. 5, in each command packet, the first cycle of the command clock corresponds to chip ID information (ID0 to ID7), which designates the slave chip to which the command is provided. The four bits (C0 to C3) of the command bus in the second cycle are assigned to be the information indicating changes in the operating state of the semiconductor integrated
circuit system 110, thereby providing a command (TV0 to TV3) indicating information regarding changes in the temperature and source voltage. Thus, in each cycle of the read/write operation, after oneslave chip 2 is designated, information indicating changes in the temperature and source voltage is sent, so as to reset the clockphase adjustment circuit 22 of thecorresponding slave chip 2 before the read/write operation is performed. The remaining four bits (C4 to C7) of the command bus in the second cycle are assigned to be other information, such as, for example, row addresses (RA0 to RA3) of theslave chip 2. - FIG. 6 is a timing diagram illustrating another example of the operation of the semiconductor integrated
circuit system 110 from initialization to a read/write operation. The initialization operation is the same as that illustrated in FIG. 4. In the example illustrated in FIG. 6, after a read/write operation is started, the re-setting of the clockphase adjustment circuit 22 of eachslave chip 2 is not performed for each cycle of the read/write operation, but is performed at every occurrence of a predetermined time period during the read/write operation. In such a case, a command for resetting the clockphase adjustment circuit 22 of theslave chip 2 may be output at every occurrence of the predetermined time period. Although not particularly illustrated in the figure, the re-setting of the clockphase adjustment circuit 22 may be performed for oneslave chip 2 each time, or may be performed for all of theslave chips 2 at once. - When the phase is re-set at every occurrence of the predetermined time period, as described above, the efficiency of the read/write operation can be improved from that when the phase re-setting is performed for each cycle of the read/write operation. There is also an advantage that the length of each command packet is reduced.
- Next, the operation of the
master chip 1 for producing a command including information indicating changes in the operating state of the semiconductor integratedcircuit system 110 will be described in greater detail. - FIG. 7 illustrates an example of a configuration of the
detection circuit 11 according to the present example. As illustrated in FIG. 7, thedetection circuit 11 includes atemperature detection circuit 11 a, avoltage detection circuit 11 b and a reference voltage generation circuit 11 c. The reference voltage generation circuit lic generates a predetermined reference voltage independently of the temperature and source voltage of the semiconductor integratedcircuit system 110. The reference voltage generation circuit 11 c can be configured based on a conventional technique. For example, the “REFERENCE VOLTAGE GENERATOR” described in U.S. Pat. No. 5,448,159 can be used. Thetemperature detection circuit 11 a includes a PLL therein, and utilizes the phenomenon that an output VCO of a voltage controlled oscillator included in the PLL varies as the temperature changes. Thus, changes in the temperature are detected by comparing the value VCO and each of the values VR1 to VR3 (obtained by subjecting the reference voltage Vref provided by the reference voltage generation circuit 11 c to voltage division usingregister elements 1 to 5), at comparison circuits L1 to L3, and thereby determining the difference therebetween. The detection results are output from the comparison circuits L1 to L3 as temperature change detection signals T1 to T3. - Moreover, the
voltage detection circuit 11 b detects changes in the source voltage by comparing a voltage value VCMP (obtained by dividing a system source voltage VDD byresistor elements 6 and 7) and the reference voltage Vref (provided by the reference voltage generation circuit 11 c) at comparison circuits R1 to R3, and thereby determining the difference therebetween. The detection results are output from the comparison circuits R1 to R3 as source voltage detection signals V1 to V3. - The temperature change detection signals T1 to T3 and the source voltage detection signals V1 to V3 are digital signals, as will be described later.
- FIG. 8 illustrates an example of a configuration of the
command production circuit 12 according to the present example. As illustrated in FIG. 8, thecommand production circuit 12 includes a temperature-sidecommand production circuit 12 a and a voltage-sidecommand production circuit 12 b. As illustrated in FIG. 8, the temperature-sidecommand production circuit 12 a receives and encodes the temperature change detection signals T1 to T3 so as to output a 2-bit command (TV0 and TV1) of temperature change information. FIG. 9A illustrates an example of encoding by the temperature-sidecommand production circuit 12 a. As illustrated in FIG. 9A, a temperature setting value is determined in accordance with the value of each bit (TV0 and TV1) of the command of temperature change information. In eachslave chip 2, the amount of delay for the clockphase adjustment circuit 22 is re-adjusted based on the temperature setting which is determined by this command. - Similarly, as illustrated in FIG. 8, the voltage-side
command production circuit 12 b receives and encodes the source voltage detection signals V1 to V3 so as to output a 2-bit command (TV2 and TV3) of voltage change information. FIG. 9B illustrates an example of encoding by the voltage-sidecommand production circuit 12 b. As illustrated in FIG. 9B, a voltage setting value is determined in accordance with the value of each bit of the command of voltage change information (TV2 and TV3). In eachslave chip 2, the amount of delay for the clockphase adjustment circuit 22 is re-adjusted based on the voltage setting which is determined by this command. - Next, the extraction of information indicating a state change from a command in each
slave chip 2, and the clock phase adjustment based on the extracted information will be described in detail. - FIG. 10 illustrates a detailed circuit configuration of the
extraction circuit 21 in eachslave chip 2 of the semiconductor integratedcircuit system 110 as illustrated in FIG. 2. As illustrated in FIG. 10, theextraction circuit 21 includes a latch circuit 42 (42 a to 42 d) for latching the command (TV0 to TV3) provided by thecommand input circuit 23, and an information extraction section 43 (43 a to 43 p) for extracting information indicating changes in the temperature and source voltage. - The command TV0 to TV3 of change-related information indicating changes in the temperature and source voltage is provided from a command bus 41 (4 bits in the present example) in the
extraction circuit 21 to thelatch circuit 42. Thelatch circuit 42 includes thelatch sections 42 a to 42 d corresponding to the respective bits, and thelatch sections 42 a to 42 d are controlled by a latchcircuit control signal 51.Outputs 52 a to 52 d respectively from thelatch sections 42 a to 42 d and outputs 53 a to 53 d complementary thereto are provided to theinformation extraction section 43. Theinformation extraction section 43 decodes the latched 4-bit command TV0 to TV3 using thedecoder sections 43 a to 43 p so as to output adjustment signals 54 a to 54 p which correspond to 16 different setting values provided in accordance with the changes in the temperature and source voltage. The adjustment signal 54 (54 a to 54 p) obtained by theextraction circuit 21 is provided to the clockphase adjustment circuit 22. - As described above, in the present example, the 4-bit command TV0 to TV3 carries information including a temperature change (2 bits) and a source voltage change (2 bits). Thus, with the four different temperature conditions and the four different voltage conditions in combination, it is possible to have 16 different settings. The present invention is not limited to such an example. Accordingly, any other number of bits provided for a command can be set as necessary.
- FIG. 11 is a diagram illustrating a detailed circuit configuration of the clock
phase adjustment circuit 22 in eachslave chip 2 of the semiconductor integratedcircuit system 110 as illustrated in FIG. 2. As illustrated in FIG. 11, the clockphase adjustment circuit 22 includes a delayamount setting circuit 61, a clock signalinput switching circuit 62 and aclock delay circuit 63. - The
clock delay circuit 63 includes a plurality ofdelay circuits 63 a to 63 p. In each of thedelay circuits 63 a to 63 p, an amount of delay in accordance with the system operating condition such as the temperature and voltage is set. For example, a reference amount of delay is set in thedelay circuit 63 a so as to use thedelay circuit 63 a as a delay circuit for a normal condition. Similarly, thedelay circuit 63 b may be used for a normal temperature/low voltage condition, thedelay circuit 63 c for a normal temperature/high voltage, and the delay circuit 63 d for a high temperature/reference voltage condition, for example. In the present example, 16 different delay amounts (respectively corresponding to thedelay circuits 63 a to 63 p) can be set corresponding to 16different output signals 54 provided by theextraction circuit 21. Moreover, the adjustment signal 54 (54 a to 54 p) output from theextraction circuit 21 is input to the clock signalinput switching circuit 62. - At the above-described initialization, an initialization signal provided to the
slave chip 2 from themaster chip 1 is input to the delayamount setting circuit 61 via a delay amount settingsignal input terminal 60. A predetermined amount of delay in accordance with the initialization signal is set (stored) in the delayamount setting circuit 61. The clockphase adjustment circuit 22 delays, by a predetermined amount, a clock signal (command clock CLK1) input from a clock input terminal 65 by using one of thedelay circuits 63 a to 63 p (e.g., thedelay circuit 63 a for a normal condition) selected in accordance with the predetermined amount of delay stored in the delayamount setting circuit 61. Then, the delayed command clock CLK1 is output from a delayedclock output terminal 66 as a phase-adjusted clock signal (data clock CLK2). - The selection of one of the
delay circuits 63 a to 63 p used in theclock delay circuit 63 is performed by the clock signalinput switching circuit 62. The clock signalinput switching circuit 62 includes switchingelements 62 a to 62 p and selects one of thedelay circuits 63 a to 63 p in accordance with the adjustment signal 54 (54 a to 54 p) so as to input the clock signal to the selected delay circuit. Each of thedelay circuits 63 a to 63 p have respective delay amounts corresponding to the conditions (the temperature, the voltage, etc.) defined by theadjustment signal 54. - Thus, information indicating changes in the operating state of the semiconductor integrated circuit system110 (i.e., changes in conditions such as the temperature and source voltage) is provided from the
master chip 1 to theslave chip 2 via the command VT0 to VT3. In eachslave chip 2, the change-related information is extracted (decoded) from a command provided by theextraction circuit 21, switching of thedelay circuits 63 a to 63 p of the clockphase adjustment circuit 22 is performed based on the extracted information so as to re-set the amount of delay of the clock signal in accordance with changes in the condition. Thus, it is possible to suppress the variation in the clock signal among the slave chips due to changes in the operating state of the semiconductor integratedcircuit system 110, thereby realizing the stable operation of the system. - In the clock
phase adjustment circuit 22, the clock signalinput switching circuit 62 is provided before (i.e., on the input side of) theclock delay circuit 63, so as to selectively use one of thedelay circuits 63 a to 63 p. Alternatively, such a switching circuit may be provided after theclock delay circuit 63 so as to selectively output a clock having a predetermined amount of delay on the output side of theclock delay circuit 63. In order to ensure that the output of the delay circuit to which a signal is not input has a high impedance, a switching circuit may also be provided on the output-sideclock delay circuit 63 as well as on the input side thereof. - Although only the temperature and source voltage are described as conditions indicating changes in the operating state of the semiconductor integrated
circuit system 110 in the present example, it is also possible to employ any one of, or a combination of, other process variations in addition to or in lieu of the temperature and/or source voltage. - Next, another example of the configuration of the clock
phase adjustment circuit 22 will be described. - FIG. 12 is a diagram illustrating another example of the configuration of the clock phase adjustment circuit22 (namely, a clock
phase adjustment circuit 22′) in eachslave chip 2 of the semiconductor integratedcircuit system 110 as illustrated in FIG. 2. As illustrated in FIG. 12, the clockphase adjustment circuit 22′ includes a delayamount setting circuit 70, the clock signalinput switching circuit 62, the outputsideclock delay circuit 63 and an output-side clockpath switching circuit 74. The delayamount setting circuit 70 includes a countamount setting circuit 71, acomparison circuit 72 and acounter circuit 73. Each of the elements which are also provided in the above-described clockphase adjustment circuit 22 is provided with the same reference numeral, and will not be described in detail below. - The operation of the clock
phase adjustment circuit 22′ is basically the same as that of the above-described clock phase adjustment circuit 22 (FIG. 11). The clockphase adjustment circuit 22′ illustrated in FIG. 12 performs the setting of the delay time by controlling the number of times the input clock (command clock CLK1) passes through theclock delay circuit 63. Thus, the physical size of theclock delay circuit 63 can be reduced. The details will be described hereinafter. - The delay
amount setting circuit 70 sets (stores), in the countamount setting circuit 71, a predetermined count value corresponding to an amount of delay to be set, in accordance with a delay amount setting signal provided from themaster chip 1 to the delay amount settingsignal input terminal 60 at initialization. Thecounter circuit 73 counts the number of clocks input to thecounter circuit 73. Thecomparison circuit 72 compares the count number of thecounter circuit 73 with the count setting value of the countamount setting circuit 71, and, if they match with each other, outputs a predetermined clockpath switching signal 75 to the output-side clockpath switching circuit 74. - The output-side clock
path switching circuit 74, under the control of the clockpath switching signal 75, outputs the data clock CLK2 from the delayedclock output terminal 66 only when the count number of thecounter circuit 73 matches with the count setting value set in the countamount setting circuit 71. - The selection of one of the
delay circuits 63 a to 63 p used in theclock delay circuit 63 is performed by the clock signalinput switching circuit 62, as in the above-described example. After the predetermined count setting value has been reached, the output of the selected one of thedelay circuits 63 a to 63 p is output via the output-side clockpath switching circuit 74 as the data clock CLK2. Due to such a structure, it is possible to reduce the number of stages in theclock delay circuit 63, thereby reducing the circuit scale of theclock delay circuit 63. - Next, a still another example of the circuit configuration of the clock
phase adjustment circuit 22 in theslave chip 2 of the semiconductor integratedcircuit system 110 as illustrated in FIG. 2 will be described. - FIG. 13 is a diagram illustrating a configuration of a clock
phase adjustment circuit 22″. As illustrated in FIG. 13, the clockphase adjustment circuit 22″ includes a first clockphase adjustment unit 22 a, a second clockphase adjustment unit 22 b and an output switching circuit 78. The configuration and the operation of each of the first and second clockphase adjustment units phase adjustment circuit 22 is provided with the same reference numeral, and will not be described in detail below. - As illustrated in FIG. 13, an initialization signal for setting (storing) a predetermined amount of delay at initialization is provided to a first delay amount setting signal input terminal60 a of the first clock
phase adjustment unit 22 a and to a second delay amount setting signal input terminal 60 b of the second clockphase adjustment unit 22 b. The command clock CLK1 is provided to a first clock input terminal 65 a of the first clockphase adjustment unit 22 a and to the second clock input terminal 65 b of the second clockphase adjustment unit 22 b. The internal operation of each of the first and second clockphase adjustment units phase adjustment circuit 22. - The clock
phase adjustment circuit 22″ includes the two clockphase adjustment units phase adjustment units - For example, when a clock phase adjustment is performed for each cycle of a read/write operation, as described above, the first and second clock
phase adjustment units - The two clock phase adjustment units do not necessarily have to be used alternately, but one of the clock phase adjustment units may continuously output the data clock CLK2 for a predetermined period of time. Due to the configuration of the clock
phase adjustment circuit 22″, it is possible to prevent a clock delaying operation from being interrupted when re-setting a clock delay amount. Thus, while the delay amount of one of the clock phase adjustment units is being set, the other unit can be operated, so that it is possible to perform the delay operation (phase adjustment operation) in an uninterrupted manner. - In the above-described semiconductor
integrated circuit system 110 of Example 1, changes in the operating environment of the system are detected by themaster chip 1, and the phase of the data clock (i.e., the data output clock from each slave chip) is adjusted by eachslave chip 2 in accordance with the changes in the operating state of the system based on the command provided by themaster chip 1. - According to the present example, each slave chip (semiconductor integrated circuit) is provided with a circuit for detecting changes in the operating environment of the system. The semiconductor integrated circuit of the present example includes a circuit for adjusting the phase of the data output clock which determines the timing of data output in accordance with the positional relationship with respect to the master chip, and further includes a circuit for preventing the operation of the data output clock phase adjustment circuit from changing due to changes in the operating environment of the system (e.g., the temperature, the source voltage, etc.).
- Hereinafter, the present example will be described in greater detail with reference to the Figures.
- FIG. 14 is a block diagram schematically illustrating a configuration of a semiconductor integrated circuit (slave chip)200 according to Example 2 of the present invention. As illustrated in FIG. 14, the semiconductor integrated
circuit 200 includes aclock input circuit 201 for receiving an externally-fed clock, adetection circuit 202 for detecting changes in the operating environment of the system, apower source circuit 203 for an output clock phase adjustment circuit (hereinafter, referred to simply as the “power source circuit 203”), an output clockphase adjustment circuit 204, aclock output circuit 205 and adata output circuit 206. - As illustrated in FIG. 14, the clock CLK1 which is provided from the outside of the semiconductor integrated circuit 200 (e.g., from the master chip) is input to the
clock input circuit 201 of the semiconductor integratedcircuit 200. Theclock input circuit 201 outputs the input clock CLK1 as areference clock 210 to the output clockphase adjustment circuit 204. Thedetection circuit 202 detects changes in the temperature and voltage, and outputs to the power source circuit 203 areference voltage 212, which is determined based on the changes. Thepower source circuit 203 outputs a power source potential 213 for a clock phase adjustment circuit in accordance with theinput reference voltage 212. - The output clock
phase adjustment circuit 204 shifts, by a predetermined value (amount of delay), the phase of thereference clock 210 provided by theclock input circuit 201 in accordance with the power source potential 213 provided by thepower source circuit 203, and outputs the phase-shifted clock as anoutput control clock 214 to theclock output circuit 205. Theclock output circuit 205 outputs theoutput control clock 214 to thedata output circuit 206 while also outputting theoutput control clock 214, as a strobe signal (clock CLK2) for data output by thedata output circuit 206, simultaneously with the output data, to the outside of the semiconductor integratedcircuit 200. - The
detection circuit 202 can be configured with a PLL circuit, for example. Hereinafter, an example where thedetection circuit 202 is a PLL circuit will be described in greater detail. - FIG. 15 illustrates a configuration of the semiconductor integrated
circuit 200 where thedetection circuit 202 is a PLL circuit. As illustrated in FIG. 15, the clock CLK1 provided from the outside of the semiconductor integrated circuit 200 (e.g., from the master chip) is input to theclock input circuit 201 of the semiconductor integratedcircuit 200. Theclock input circuit 201 outputs the input clock CLK1 as areference clock 210′ to thedetection circuit 202. - The detection circuit (PLL)202 includes a VCO for producing an internal clock, and varies the potential of the VCO so as to synchronize an
internal clock 211 with theinput reference clock 210″. Thedetection circuit 202 provides, as thereference voltage 212, the potential of the VCO at the time when theinternal clock 211 is synchronized with thereference clock 210′ to thepower source circuit 203. Thepower source circuit 203 outputs the power source potential 213 for a clock phase adjustment circuit based on theinput reference voltage 212. - The
detection circuit 202 provides theinternal clock 211 synchronized with thereference clock 210′ (i.e., the phase of thereference clock 210′ is equal to that of the internal clock 211) to the output clockphase adjustment circuit 204. The output clockphase adjustment circuit 204 shifts, by a predetermined value (amount of delay), the inputinternal clock 211, and outputs the shifted clock as theoutput control clock 214 to theclock output circuit 205. Theclock output circuit 205 outputs theoutput control clock 214 to thedata output circuit 206. - The
data output circuit 206 outputs data in the semiconductor integratedcircuit 200 in accordance with the providedoutput control clock 214. The data in the semiconductor integratedcircuit 200 is, for example, data read out from a memory, the result of a predetermined arithmetic operation, or the like. Moreover, simultaneously with the data output by thedata output circuit 206, theclock output circuit 205 outputs theoutput control clock 214 as a strobe signal for the output data. - When the operating environment (e.g., the temperature, the source voltage, etc.) of the semiconductor integrated
circuit 200 changes, the operation of the output clockphase adjustment circuit 204 changes accordingly. In the present example, thepower source circuit 203 is employed in order to prevent such a change in the operation of the output clockphase adjustment circuit 204. Thus, when the temperature, the source voltage, etc., changes, thedetection circuit 202 varies the potential of the VCO in thedetection circuit 202 in order to match the phase of the externally-input reference clock 210′ with that of the inputinternal clock 211. Since thepower source circuit 203 uses the potential of the VCO (the reference voltage 212) as the reference voltage for the operation thereof, the power source potential 213 for a clock phase adjustment circuit, which is output by thepower source circuit 203, changes in accordance with the change in thereference voltage 212. Due to the power source potential 213 which changes as described above, the change in the operation of the output clockphase adjustment circuit 204 is suppressed. - FIG. 16 illustrates a waveform of a clock input to the semiconductor integrated
circuit 200. As illustrated in FIG. 16, the frequency of the input clock is lower in a stand-by mode than in an operating mode. By setting the frequency of the input clock as described above, it is possible to suppress the current consumption by the semiconductor integratedcircuit 200 in a stand-by mode. - FIG. 17 illustrates an example of a circuit configuration of the
power source circuit 203. As illustrated in FIG. 17, thepower source circuit 203 generates thesource voltage 213 in accordance with the change in thereference voltage 212. - Moreover, in order to reduce the power consumption by the semiconductor integrated
circuit 200, thepower source circuit 203 may be configured to include two power source circuits; one for an operating mode and another for a stand-by mode. The power source circuit for an operating mode may be one which has a high response speed and a large power consumption. On the other hand, the power source circuit for a stand-by mode may be one which has a low response speed and a small power consumption. By configuring thepower source circuit 203 as descried above, it is possible to reduce the power consumption in a stand-by mode while maintaining a high-speed operation in an operating mode. - Furthermore, in order to reduce the power consumption by the semiconductor integrated
circuit 200 as illustrated in FIG. 15, a clock frequency divider may be provided. For example, in FIG. 15, thereference clock 210′ output by the clock input circuit may be provided intact to the output clockphase adjustment circuit 204, while providing it to thedetection circuit 202 as a frequency-divided clock after dividing the frequency thereof using the frequency division circuit. - FIG. 18 illustrates timing diagrams for the input clock and the frequency-divided clock. As illustrated in FIG. 18, the frequency of the divided clock is lower than that of the input clock, so that voltage setting may be performed in the
power source circuit 203 at a low frequency, thereby reducing the power consumption accordingly. - FIG. 19 is a block diagram illustrating a configuration of another semiconductor integrated
circuit 300 of the present example. As illustrated in FIG. 19, the semiconductor integratedcircuit 300 includes theclock input circuit 201, as a first clock input circuit, and a secondclock input circuit 301. Other than this, the configuration of the semiconductor integratedcircuit 300 is the same as that of the semiconductor integratedcircuit 200 as illustrated in FIG. 15, and like components are provided with like reference numerals and will not described in detail. - The clock CLK1 provided by the master chip, or the like, is input to the first
clock input circuit 201. The clock CLK1 input to the firstclock input circuit 201 is provided to the output clockphase adjustment circuit 204 as thereference clock 210. The secondclock input circuit 301 is a temperature/voltage adjustment clock input circuit, to which a clock CLK3 is input. The clock CLK3 is used for adjusting the phase of the clock as the operating environment (e.g., the temperature, the voltage, etc.) changes. - FIG. 20 is a timing diagrams for the input clock CLK1 and the temperature/voltage adjustment clock CLK3 used in the semiconductor integrated
circuit 300. As illustrated in FIG. 20, the frequency of the temperature/voltage adjustment clock CLK3 is lower than that of the input clock CLK1. Therefore, voltage setting may be performed in thepower source circuit 203 at a low frequency, thereby reducing the power consumption accordingly. Moreover, when two different clock input circuits are provided, as described above, it is not necessary to alter the frequency of the input clock CLK1 between an operating mode and a stand-by mode, as is necessary in the example illustrated in FIG. 16. Thus, the control for switching between an operating mode and a stand-by mode is simplified. - The clock phase adjustment in the case where the
detection circuit 202 is a PLL circuit has been described above. However, any other circuit which has a similar function (e.g., a DLL circuit) may also be used as thedetection circuit 202 instead of the PLL circuit. - As described above, in the semiconductor integrated circuit system of the present invention, the clock phase adjustment circuit of each slave chip can be re-set based on information output by the detection circuit for detecting changes in the operating environment (e.g., the temperature, the source voltage, etc.). Therefore, the clock phase adjustment circuit of each slave chip can be stably operated even when the operating environment changes. Thus, it is possible to provide: a semiconductor integrated circuit system capable of stably operating at a high speed even when a semiconductor integrated circuit system has IC chips from various manufacturers, or when the circuit characteristics (e.g., the temperature dependency, the voltage dependency, etc.) vary among respective IC chips; a semiconductor integrated circuit for use in such a semiconductor integrated circuit system; and a method for driving such a semiconductor integrated circuit system.
- Various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the scope and spirit of this invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description as set forth herein, but rather that the claims be broadly construed.
Claims (17)
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JP9194637A JPH1139868A (en) | 1997-07-18 | 1997-07-18 | Semiconductor integrated circuit system, semiconductor integrated circuit, and method of driving semiconductor integrated circuit system |
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Also Published As
Publication number | Publication date |
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KR100334362B1 (en) | 2002-10-04 |
JPH1139868A (en) | 1999-02-12 |
US6393577B1 (en) | 2002-05-21 |
KR19990014039A (en) | 1999-02-25 |
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