CN102478876B - Reference voltage generating circuit and method - Google Patents

Abstract

The invention relates to a reference voltage generating circuit and a method. The reference voltage generating circuit comprises a band gap reference circuit which generates a plurality of initial currents with different temperature coefficients; a reference voltage generating circuit for synthesizing the initial currents into a synthesized current and converting the synthesized current into one or more reference voltages; a bias current source circuit for generating one or more bias currents according to at least one of the initial currents; and one or more regulated output circuits, each for converting one of the one or more bias currents into a respective delta voltage for addition with the reference voltage into a respective output reference voltage. Each output reference voltage has its own temperature coefficient, so the reference voltage generating circuit can achieve flexibility and wide application.

Description

Reference voltage generation circuit and method

technical field

The present invention relates to a reference voltage generation circuit and method, and in particular to a reference voltage generation circuit and method utilizing a bandgap reference circuit. the

Background technique

Due to the characteristics of semiconductors, in many applications, the output reference voltage of the reference voltage generating circuit needs to include a temperature coefficient (TC) to compensate for temperature effects. For example, if there is an application whose output reference voltage specification is 1.6V+10mV/℃, the adjustment range of the absolute voltage value of this output reference voltage is: 1.2V～2.0V, and the adjustable range of its temperature coefficient is 5mV/℃～ 15mV/°C. the

FIG. 1A shows a schematic diagram of adjusting the absolute voltage value of the output reference voltage. In FIG. 1A , curves A1 , B1 and C1 respectively represent output reference voltages of 1.2V+10mV/°C, 1.6V+10mV/°C and 2.0V+10mV/°C. 1B shows a schematic diagram of adjusting the temperature coefficient of the output reference voltage. Curves A2, B2 and C2 respectively represent the output reference voltages of 1.6V+5mV/°C, 1.6V+10mV/°C and 1.6V+15mV/°C. the

In order to adjust the absolute voltage value and temperature coefficient, in the existing reference voltage generation circuit, a Bandgap circuit is generally used to generate a zero-TC voltage and a positive-TC voltage. voltage), and then use an adder (subtractor) with multiple buffers to add or subtract the generated voltage to generate output reference voltages with different temperature coefficients. the

However, this type of existing architecture is too bulky and complex due to multiple buffers, resulting in much larger power consumption and circuit area than designs without temperature compensation effects. In addition, the buffers that perform voltage addition and subtraction will cause redundant offsets, which greatly affect the accuracy of the output reference voltage and its temperature coefficient. the

Contents of the invention

An object of the present invention is to provide a reference voltage generating circuit and its method, which can perform follow-up processing by extracting a current with a temperature coefficient instead of a voltage, so that multiple buffers do not need to be used, thereby having a small area and low power consumption , simple structure, accurate temperature coefficient and so on. the

Another object of the present invention is to propose a reference voltage generation circuit and its method, which can increase the temperature coefficient of the bias current by subtracting the currents to synthesize the bias current, so that the required voltage can be obtained with a smaller variable resistance. range of output reference voltages, and can widen the input range of zero temperature coefficient reference voltages. the

Another object of the present invention is to provide a reference voltage generation circuit and its method, which switch the bias current between different temperature coefficients by switching the current path, so that the output reference voltage can be switched between different temperature coefficients, thereby It can be used in various occasions, achieving flexibility and a wide range of applications. the

A reference voltage generating circuit according to one aspect of the present invention includes: a bandgap reference circuit generating a plurality of initial currents with different temperature coefficients; a reference voltage generating circuit coupled to the bandgap reference circuit for use in To copy these initial currents and synthesize them into a synthesized current, and convert the synthesized current into one or more reference voltages; a bias current source circuit, coupled to at least the bandgap reference circuit and the reference voltage generating circuit one for generating one or more bias currents according to at least one of the initial currents; and one or more regulated output circuits, each of which is coupled to the reference voltage generating circuit to receive the one or more reference voltages a corresponding one of them, and coupled to the bias current source circuit to receive a corresponding one of the one or more bias currents for converting the received bias current into an individual differential voltage for Added to the reference voltage to become an individual output reference voltage. the

A method for generating a reference voltage according to another aspect of the present invention includes: generating a plurality of initial currents with different temperature coefficients; copying these initial currents and synthesizing them into a synthetic current, and converting the synthetic current into one or more a reference voltage; respectively generating one or more bias currents according to at least one of these initial currents; Add to one of one or more output reference voltages. the

The beneficial technical effect of the present invention is: compared with the prior art, the above-mentioned embodiment carries out follow-up processing by extracting the current of the energy bandgap reference circuit instead of the voltage, so there is no need to use a plurality of buffers, thereby having a small area , low power consumption, simple structure, accurate temperature coefficient and other advantages. In addition, the bias current can be synthesized by subtracting the currents, which can increase the temperature coefficient of the bias current. As a result, a smaller variable resistance can be used to obtain the output reference voltage in the required range, and the reference voltage with zero temperature coefficient can be widened. input range. In addition, the bias current can be switched between different temperature coefficients by switching the current path, so the output reference voltage can be switched between different temperature coefficients, so that it can be applied to various occasions. the

In order to have a better understanding of the above-mentioned and other aspects of the present invention, the preferred embodiments are specifically cited below, and are described in detail in conjunction with the accompanying drawings as follows:

Description of drawings

FIG. 1A shows a schematic diagram of adjusting the absolute voltage value of the output reference voltage. the

FIG. 1B shows a schematic diagram of adjusting the temperature coefficient of the output reference voltage. the

FIG. 2 shows a schematic diagram of a reference voltage generating circuit according to a first embodiment of the present invention. the

Figure 3 shows the concept of the temperature coefficient of current. the

FIG. 4 shows a schematic diagram of a reference voltage generating circuit according to a second embodiment of the present invention. the

FIG. 5A and FIG. 5B show schematic diagrams of the reference voltage generating circuit in different aspects according to the third embodiment of the present invention. the

FIG. 6 shows a flowchart of a method for generating a reference voltage according to a fourth embodiment of the present invention. the

Detailed ways

In the reference voltage generating circuit disclosed here, the initial currents with different temperature coefficients (for example, a positive temperature coefficient current and a negative temperature coefficient current) are summed into a composite current and converted into a reference voltage, and based on these The initial current is used to generate one or more bias currents, and then one or more positive/negative/zero temperature coefficient output reference voltages are respectively generated according to the one or more bias currents and the reference voltage. Several embodiments are given below for illustration. the

first embodiment

Please refer to FIG. 2 , which shows a schematic circuit diagram of a reference voltage generating circuit according to a first embodiment of the present invention. As shown in FIG. 2 , the reference voltage generation circuit 200 includes: a bandgap reference circuit 210, a reference voltage generation circuit 220, a bias current source circuit 230, and one or more regulated output circuits (here, two regulated output circuits 240A and 240B as an example). The following description can be easily deduced to a larger number of regulated output circuits. the

The bandgap reference circuit 210 is configured to generate initial currents with different temperature coefficients. In a preferred situation, the initial currents include a first current I1 with a positive temperature coefficient and a second current I2 with a negative temperature coefficient. the

The reference voltage generating circuit 220 is coupled to the bandgap reference circuit 210, and is configured to replicate the initial current generated by the bandgap reference circuit 210, synthesize it to generate a synthesized current, and then convert the synthesized current into a or multiple reference voltages. In the preferred embodiment shown in FIG. 2, the reference voltage generating circuit 220 replicates the first current I1 and the second current I2 and synthesizes it into a third current I3 with a zero temperature coefficient, and converts the third current I3 into a current with a zero temperature coefficient. The reference voltage V1 and V2 of the temperature coefficient. the

The bias current source circuit 230 is coupled to at least one of the bandgap reference circuit 210 and the reference voltage generating circuit 220 . The bias current source circuit 230 generates one or more bias currents according to at least one of the first current I1 and the second current I2 . In this figure, it is illustrated by taking two bias currents equal to the first and second currents I1 and I2 respectively. the

Both the regulated output circuits 240A and 240B are coupled to the reference voltage generation circuit 220 to receive corresponding reference voltages V1 and V2 respectively. In addition, the regulated output circuits 240A and 240B are respectively coupled to the bias current source circuit 230 to receive corresponding bias currents (hereinafter, receiving the second current I2 and the first current I1 will be taken as an example). The regulated output circuits 240A and 240B can then respectively convert the received bias currents into individual differential voltages (that is, the individual voltages across the resistors R4 and R5) to be added to the reference voltages V1 and V2 respectively to form individual outputs Reference voltages Vout1 and Vout2. the

FIG. 2 also shows exemplary detailed circuit structures of the bandgap reference circuit 210 , the reference voltage generating circuit 220 , the bias current source circuit 230 , and the regulated output circuits 240A and 240B, respectively. It should be noted that the detailed structure of the example in FIG. 2 is only for illustration, and various circuit structures can be used to implement the bandgap reference circuit 210, the reference voltage generating circuit 220, the bias current source circuit 230 and the regulated output circuit 240A. And 240B, as long as the above functions can be achieved. the

In the example shown in FIG. 2 , the bandgap reference circuit 210 may include, for example: a proportional to absolute temperature (PTAT, proportional to absolute temperature) current generating circuit 210A configured to generate a first current I1 with a positive temperature coefficient and a voltage-to-current conversion circuit 210B, coupled to a node proportional to the absolute temperature current generation circuit 210A, for converting the voltage VEB1 of the node into a second current I2 with a negative temperature coefficient. The advantage of using this voltage-to-current circuit to convert the negative temperature coefficient voltage (such as the node voltage VEB1 ) into the second current I2 with negative temperature coefficient is that the number of components can be reduced to reduce the circuit area. the

Specifically, in the PTAT current generating circuit 210A of this example, a pair of junction transistors T25 and T26, such as PNP bipolar junction transistors (BJT), are provided, and the collectors and bases of both are coupled to to a reference voltage (such as ground GND). The junction transistors T25 and T26 have different current area densities, for example, the area of the junction transistor T25 (such as A) is smaller than the area of the junction transistor T26 (such as nA, where n is a positive integer greater than 1). On the other hand, the PTAT current generating circuit 210A is also provided with a pair of field effect transistors T23 and T24, such as N-type metal oxide semiconductor field effect transistors (NMOS), the gates of the two are connected, and the drains are respectively coupled to The emitters of transistors T25 and T26 are connected, and the gate and source of field effect transistor T23 are connected. In addition, the PTAT current generating circuit 210A is also provided with another pair of field effect transistors T21 and T22, such as P-type metal oxide semiconductor field effect transistors (PMOS), the gates of the two are connected, and the sources are both coupled to the other A reference voltage (such as VDD), and the drains are respectively coupled to the sources of the field effect transistors T25 and T26. Under the connection configuration of the field effect transistors T21 to T24 , the drain voltages of the field effect transistors T23 and T24 can be equal, that is, both are equal to the base-emitter voltage VEB1 of the junction transistor T25 . Therefore, the voltage V1=VEB1-VEB2=KTln(n) across the first resistor R1 can be derived, that is, the first current I1=KTln(n)/R1 flowing through the first resistor R1. In other words, the temperature coefficient of the first current I1 is positive. the

On the other hand, the exemplary detailed structure of the voltage-to-current conversion circuit 210B shown in FIG. 2 includes an operational amplifier OP1 and a resistor R2. Due to the virtual short circuit, the two input terminals of the operational amplifier OP1 are locked at the same voltage, that is, the node voltage VEB1 of the PTAT current generating circuit 210A. Through the resistance characteristic of the resistor R2, the node voltage can be converted into a second current I2: I2=VEB1/R2. Since VEB1 is a voltage with a negative temperature coefficient, the temperature coefficient of the second current I2 is also negative. In addition, the voltage-to-current conversion circuit 210B is provided with a field effect transistor T27, the gate voltage of which can reflect the magnitude of the second current. the

On the other hand, in the exemplary detailed structure of the reference voltage generating circuit 220 shown in FIG. The poles are respectively coupled to the bandgap reference circuit 210 for replicating the first current I1 and the second current I2 respectively. In addition, the reference voltage generating circuit 220 also includes a resistor R3, which is coupled to the source of the first mirroring transistor T28 and the source of the second mirroring transistor T29, and is used for combining the first current I1 and the second current. I1 becomes the third current I3, and converts the third current I3 into one or more reference voltages (for example, V1 and V2 here) by using its resistance characteristic. Optionally, the third resistor R3 can be a variable resistor. For example, by setting one or more multiplexers (such as multiplexers MUX1 and MUX2 here) respectively coupled to the resistor R3, the resistance value of the resistor R3 can be selected by using the control signals C1 and C2. The voltage levels of the reference voltages V1 and V2 are adjusted. It should be noted that, here only a single resistor R3 is set as an example, in fact, multiple resistors can also be set to convert one or more reference voltages respectively. the

FIG. 3 shows a schematic diagram of changes of the first to third currents I1 ˜ I3 with temperature. In a preferred situation, through proper circuit design, the sum of the first current and the second current, that is, the third current I3 flowing through the resistor R3 can be a current with zero temperature coefficient. For example, assuming that the temperature coefficient of the first current I1 is +10μA/℃, and the temperature coefficient of the second current I2 is -10μA/℃, then the temperature coefficient of the third current I3 is +10μA/℃+(-10μA/℃) = 0 μA/°C. Since the third current I3 is a zero temperature coefficient current, the voltage across the resistor R3 is also a zero temperature coefficient voltage. Under the control of the control signals C1 and C2, the multiplexers MUX1 and MUX2 take appropriate voltages from the resistor R3 to become the reference voltages V1 and V2, wherein the voltages V1 and V2 are also zero temperature coefficient voltages. the

Continue to refer to Figure 2. In the exemplary detailed structure of the bias current source circuit 230 shown in FIG. 2 , the bias current source circuit 230 may include mirroring transistors T30 - T32 and T35 . With proper gate connections, the transistors T30 , T31 and T35 can reproduce the positive temperature coefficient of the first current I1 by current mirroring of the transistors T21 , T22 and T28 . Similarly, the transistor T32 can replicate the second current I2 with a negative temperature coefficient by current mirroring of the transistors T27 and T32 with proper gate connections. the

On the other hand, in the exemplary detailed structure shown in FIG. 2 , two regulated output circuits 240A and 240B are taken as an example for illustration. In this example, the regulated output circuits 240A and 240B can be Class A (Class A) regulated output circuits. In detail, in the voltage stabilizing output circuit 240A, a resistive element (such as a variable resistor R4) is configured, which has a first end coupled to the output node Vout1, and a second end that is copied by the receiving mirror transistor T32. The output of the second current I2. In addition, the regulated output circuit 240A also includes an output transistor T33 coupled between the output node Vout1 and a reference level (for example, ground GND), and an operational amplifier OP2, which has a first input end receiving the reference voltage V1, and a first input end receiving the reference voltage V1. Two input terminals are coupled to the variable resistor R4, and one output terminal is coupled to the gate of the output transistor T33. Similarly, a resistive element (such as a variable resistor R5), an output transistor T34, and an operational amplifier OP3 are also configured in the voltage stabilizing output circuit 240B. The connection method is similar to that of the voltage stabilizing output circuit 240A, except that the variable resistor R5 Instead, the second current I1 copied by the mirroring transistor T35 is received, and both the variable resistor R5 and the output transistor T34 are coupled to the output node Vout2. the

In the regulated output circuit 240A, the voltage at the second end of the variable resistor R4 can be equal to the reference voltage V1 through the virtual short circuit of the operational amplifier OP2. In addition, through the resistance characteristic of the variable resistor R4, a differential voltage -I2*R4 across the variable resistor R4 can be generated. Therefore, the output reference voltage Vout1 is equal to the reference voltage V1 plus the difference voltage (-I2*R4), which can be expressed as: Vout1=V1-I2*R4. Under the preferred condition that the reference voltage V1 is a voltage with zero temperature coefficient and the second current I2 is a current with a negative temperature coefficient, the output reference voltage Vout1 can therefore be a voltage with a positive temperature coefficient, and the temperature coefficient can be adjusted by the variable resistor R4. Similarly, through the operation of the operational amplifier OP3 and the variable resistor R5, the output reference voltage Vout2 is equal to the reference voltage V2 plus the differential voltage I1*R5, which can be expressed as: Vout1=V2+I1*R5. In the preferred case where the reference voltage V2 is a voltage with zero temperature coefficient and the first current I1 is a current with a positive temperature coefficient, the output reference voltage Vout2 can also be a voltage with a positive temperature coefficient, and the temperature coefficient can also be adjusted by the variable resistor R5. the

To sum up, the reference voltage generation circuit 200 can first generate the first and second currents I1 and I2 with different temperature coefficients through the bandgap reference circuit 210, and then use the reference voltage generation circuit 220 to perform current mirroring and conversion to generate The reference voltage with zero temperature coefficient, and the bias current source circuit 230 performs current mirroring to replicate one or more bias currents, and then uses the voltage-stabilizing output circuits 240A-240B to convert the reference voltage to the one or more bias currents is one or more output reference voltages that can have different temperature coefficients. the

Compared with the existing technology with complex structure and large area, the reference voltage generating circuit 200 does not use multiple buffers to add or subtract the voltage of the bandgap reference circuit, but takes out the voltage generated by the bandgap reference circuit. current (herein referred to as the initial current) and use the bias current source circuit 230, the reference voltage generating circuit 220 and the voltage stabilizing output circuit 240A-240B with a smaller area and a simpler structure for subsequent processing, and finally one or more Output reference voltages with different temperature coefficients have the advantages of small area, low power consumption, simple structure, and accurate temperature coefficients. the

It should be noted that, in other embodiments, different current mirroring paths can be designed so that the current flowing through the variable resistor R4 is changed to a positive temperature coefficient current I1, so that the output reference voltage Vout1 becomes a negative temperature coefficient voltage . Additionally or additionally, different current mirroring paths can be designed so that the current flowing through the variable resistor R5 is a negative temperature coefficient current I2, so that the output reference voltage Vout2 becomes a negative temperature coefficient voltage. In other words, there are various combinations of positive and negative values of the temperature coefficients of the output reference voltages Vout1 and Vout2 , and the values can be adjusted through the variable resistors R4 and R5 . the

Furthermore, in other embodiments, a greater or lesser number of bias current and voltage regulation output circuits may be implemented to provide a greater or lesser number of output reference voltages with the same or different temperature coefficients. What's more, the composite current and the reference voltage generated by the reference voltage generating circuit 220 are not limited to zero temperature coefficient, but may have a non-zero temperature coefficient. Therefore, the technology disclosed here can be widely and flexibly applied. the

Second embodiment

Please refer to FIG. 4 , which shows a schematic circuit diagram of a reference voltage generating circuit according to a second embodiment of the present invention. Similar to the reference voltage generation circuit 200 of FIG. 2 , the reference voltage generation circuit 400 of FIG. 4 includes: a bandgap reference circuit 410, a reference voltage generation circuit 420, a bias current source circuit 430 and one or more regulated output circuits (in This is also illustrated by taking the two regulated output circuits 440A and 440B as an example). the

In the example shown in FIG. 4 , the bandgap reference circuit 410 may also include a current proportional to absolute temperature generating circuit 410A and a voltage-to-current converting circuit 410B. However, compared with the reference voltage generating circuit 200 shown in FIG. 2 , the difference of the reference voltage generating circuit 400 shown in FIG. 4 is that the bias current source circuit 430 does not simply copy the first and second currents I1 and I2 into Instead, an additional current synthesis function is added to provide bias currents with different temperature coefficients, so that the regulated output circuits 440A and 440B can generate output reference voltages with different temperature coefficients. In the following, only the differences between the reference voltage generating circuits 200 and 400 will be described, and the rest can refer to the description of the first embodiment. the

In the example shown in this figure, current subtraction is used to illustrate this current synthesis function, which can increase the temperature coefficient of the output reference voltage. In order to achieve this current subtraction function, the bias current source circuit 430 is additionally provided with transistors T41 - T50 for mirroring. the

Through the current mirroring of the transistor T27, the mirroring transistors T41, T42 and T43 can reproduce the second current I2 (negative temperature coefficient current). In addition, similar to FIG. 2 , the mirroring transistor T30 can reproduce the first current I2. Therefore, the bias current I4=I1-I2 flowing through the mirroring transistor T31 is a current with a positive temperature coefficient. Finally, through the current mirroring of the mirroring transistor T31, the mirroring transistor T35 can also replicate the bias current I4 to provide the voltage-stabilizing output circuit 440B for use. the

Similarly, the mirroring transistors T44 , T45 and T46 can replicate the first current I1 (positive temperature coefficient current) through the current mirroring of the transistors T21 and T22 . Through the current mirroring of the transistor T27 and the appropriate size design between the transistors, the mirroring transistors T41 and T47 can reproduce I2' (negative temperature coefficient current), which is a multiple of the second current I2, and the current magnitude relationship It is: I2'>I1>I2. Therefore, the bias current I5=I2'-I1 flowing through the mirroring transistor T48 is a current with a negative temperature coefficient. Finally, through the current mirroring of the mirroring transistor T48, the mirroring transistors T50, T49, and T32 can also replicate the bias current I5 for use by the voltage-stabilizing output circuit 440A. the

Please refer back to FIG. 3, which shows the temperature coefficients of the bias currents I4 and I5. It can be seen from FIG. 3 that although the currents I1 and I4 are positive temperature coefficient currents, the absolute value of the temperature coefficient of the current I4 is greater than the absolute value of the temperature coefficient of the bias current I1 . In addition, although the bias currents I2, I2' and I5 are all negative temperature coefficient currents, the absolute value of the temperature coefficient of the bias current I5 is greater than the absolute value of the temperature coefficient of the second current I2. For example, assuming that the temperature coefficient of current I1 is +10μA/°C, and the temperature coefficient of current I2 is -10μA/°C, then the temperature coefficient of current I4 is +10μA/°C-(-10μA/°C)=+20μA/°C , and the temperature coefficient of the current I5 is -10μA/°C-(+10μA/°C)=-20μA/°C. the

Please continue to refer to Figure 4. In the regulated output circuit 440A, the reference voltage Vout1=V1−I5*R4 is output. Under the preferred condition that the reference voltage V1 is a voltage with zero temperature coefficient and the bias current I5 is a current with a negative temperature coefficient, the output reference voltage Vout1 is a voltage with a positive temperature coefficient. Similarly, in the regulated output circuit 440B, the output reference voltage Vout2=V2+I4*R5. Under the preferred condition that the reference voltage V2 is a voltage with zero temperature coefficient and the bias current I4 is a current with a positive temperature coefficient, the output reference voltage Vout2 is a voltage with a positive temperature coefficient. As mentioned in the related description of FIG. 3 , since the temperature coefficients of the bias currents I4 and I5 have larger absolute values, the temperature coefficients of the output reference voltages Vout1 and Vout2 are also increased. the

In summary, the bias current I4 is generated by subtracting the first current I1 with a positive temperature coefficient from the second current I2 with a negative temperature coefficient, or subtracting the second current with a positive temperature coefficient from the first current I2' with a negative temperature coefficient I1 is used to generate the bias current I4, which can increase the temperature coefficient of the bias currents I4 and I5, even up to several times. Therefore, this embodiment can produce various advantages. For example, the required range of output reference voltages Vout2 and Vout1 can be obtained with relatively small variable resistors R4 and R5, which helps to reduce the circuit area. In addition, the bias currents I4 and I5 obtained by current subtraction can also be greatly reduced, so the voltage drop caused by the variable resistors R4 and R5 can be reduced, and as a result, the input range of the reference voltages V1 and V2 with zero temperature coefficient can be widened . the

It is worth noting that, similar to FIG. 2 , in other embodiments, different current mirroring paths can be designed so that the current flowing through the variable resistor R4 can be changed to a positive temperature coefficient current I4, thereby making the output reference voltage Vout1 variable. is a negative temperature coefficient voltage. Additionally or additionally, different current mirroring paths can be designed so that the current flowing through the variable resistor R5 is a negative temperature coefficient current I5 , so that the output reference voltage Vout2 becomes a negative temperature coefficient voltage. In other words, there are various combinations of positive and negative values of the temperature coefficients of the output reference voltages Vout1 and Vout2 , and the values can be adjusted through the variable resistors R4 and R5 . the

Furthermore, in other embodiments, a greater or lesser number of bias current and voltage regulation output circuits may be implemented to provide a greater or lesser number of output reference voltages with the same or different temperature coefficients. What's more, the composite current and the reference voltage generated by the reference voltage generating circuit 420 are not limited to zero temperature coefficient, but may have a non-zero temperature coefficient. the

In addition, it is also worth noting that in the example shown in FIG. 4 , the current synthesis function is illustrated by current subtraction, which can increase the temperature coefficient of the output reference voltage. However, in other embodiments, the bias current source circuit 430 can implement other different types of current synthesis, such as the addition and subtraction of the first and second currents I1 and I2 with different weights, so as to generate output references with different temperature coefficients. Voltage. What's more, when the bandgap reference circuit 410 generates more initial currents, more types of current synthesis can be implemented according to these initial currents, so as to generate output reference voltages with different temperature coefficients. The techniques disclosed herein can be used in a wide range of applications and flexibility. the

third embodiment

Please refer to FIG. 5A and FIG. 5B , which are schematic circuit diagrams of a reference voltage generating circuit 500 according to a third embodiment of the present invention. Similar to the reference voltage generating circuit 400 in FIG. 4 , the reference voltage generating circuit 500 in FIG. 5A and FIG. 5B includes: a bandgap reference circuit 510, a reference voltage generating circuit 520, a bias current source circuit 530, and one or more regulated voltage outputs circuit (here also take two regulated output circuits 540A and 540B as an example for illustration). In the example shown in FIG. 5A and FIG. 5B , the bandgap reference circuit 510 may also include a current proportional to absolute temperature generating circuit 510A and a voltage-to-current converting circuit 510B. However, compared with the reference voltage generating circuit 400 shown in FIG. 4, the difference between the reference voltage generating circuit 500 shown in FIG. 5A and FIG. The piezoelectric current can be flexibly switched between different temperature coefficients, so the output reference voltages of the voltage stabilizing output circuits 540A and 540B can also flexibly switch between different temperature coefficients. In the following, only the differences between the reference voltage generating circuits 400 and 500 will be described, and the rest can refer to the descriptions of the first and second embodiments. the

In order to achieve this current path switching function, the bias current source circuit 530 is additionally equipped with switches SW1-SW4, and the switch combination can have four states in total, which are state 1: (SW1 is on, SW3 is off; SW2 is on SW4 is cut off), pattern two: (SW1 is turned on and SW3 is turned off; SW2 is turned off and SW4 is turned on), pattern three: (SW1 is turned off and SW3 is turned on; SW2 is turned on and SW4 is turned off), and pattern four: (SW1 is turned off and SW3 is turned on on; SW2 cuts off and SW4 turns on). FIG. 5A and FIG. 5B respectively show the first aspect and the third aspect, and other aspects can be easily deduced by analogy. In practical applications, the switches SW1 - SW4 can be designed to operate in one or more of the above-mentioned aspects 1-4, for example, the aspects 1 and 3. the

Referring to FIG. 5A , in Aspect 1, the switches SW1 and SW2 are turned on and the switches SW3 and SW4 are turned off, so the operation of the reference voltage generating circuit 500 is substantially the same as that of the reference voltage generating circuit 400 of FIG. 4 . That is, the bias currents I4 and I5 generated by the bias current source 530 have positive temperature coefficients and negative temperature coefficients respectively, so the output reference voltages Vout1 and Vout2 of the voltage stabilizing output circuits 540A and 540B both have positive temperature coefficients Voltage. the

Turning to FIG. 5B , in the third aspect, since the switch SW2 is turned off and the switch SW4 is turned off, the current flowing through the mirroring transistor T48 is I1+I2, which has zero temperature coefficient under proper design. The current mirroring of the mirroring transistors T50 , T49 and T32 can also replicate the bias current I1+I2 for the voltage stabilizing output circuit 540A. Similarly, since the switch SW1 is off and the switch SW3 is off, the current flowing through the mirroring transistor T31 is I1+I2, which has a zero temperature coefficient under proper design. The mirroring transistors T31 and T35 can also reproduce the bias current I1+I2 for the voltage stabilizing output circuit 540B. the

To sum up the above, the bias current generated by the bias current source can be switched between combinations with different temperature coefficients through the switching functions of the switches SW1 - SW4 . For example, in the third state, the bias currents have zero temperature coefficients; and in the first state, the bias currents have positive and negative temperature coefficients respectively. As a result, the combination of temperature coefficients of the output reference voltages Vout1 and Vout2 can also be switched between combinations of different temperature coefficients. Therefore, the reference voltage generating circuit 500 can be applied to occasions where switching between the presence/absence of the temperature coefficient is required, or can meet various requirements of different applications at the same time. . the

It should be noted that, similar to FIG. 4 , in other embodiments, different current mirror paths can be designed to generate bias currents and output reference voltages with different temperature coefficients. For example, the voltage-stabilizing output circuits 540A and 540B can be changed to receive bias currents I4 and I5 in a certain state, so that the output reference voltages Vout1 and Vout2 in a certain state both become negative temperature coefficient voltages. In other words, there are various combinations of positive and negative values of the temperature coefficients of the output reference voltages Vout1 and Vout2 , and the values can be adjusted through the variable resistors R4 and R5 . Moreover, in other embodiments, more or less number of regulated output circuits can be implemented to provide more or less number of output reference voltages with the same or different temperature coefficients. What's more, the composite current and the reference voltage generated by the reference voltage generating circuit 520 are not limited to zero temperature coefficient, but may have a non-zero temperature coefficient. the

In addition, it is also worth noting that in the examples shown in FIG. 5A and FIG. 5B , current addition, subtraction and addition are used to illustrate the functions of current synthesis and switching in different states. However, in other embodiments, the bias current source circuit 530 can implement various other types of current synthesis and/or current path switching, such as adding and subtracting the first and second currents I1 and I2 with different weights, so as to Generate output reference voltages with different temperature coefficients. What's more, when the bandgap reference circuit 510 generates more initial currents, more types of current synthesis and switching can be implemented according to these initial currents, so as to generate output reference voltages with different temperature coefficients. Therefore, the technology disclosed here can be widely and flexibly applied. the

It should be noted that the above-mentioned first to third embodiments can be selectively combined with each other to form other possible embodiments. For example but not limited to, in other possible embodiments, the bias current source circuit may include any number of combinations of the bias current source circuits 230, 430 and 530 of FIGS. The regulated output circuit to generate various bias currents and output reference voltages. the

The fourth embodiment of the present invention discloses a method for generating a reference voltage. FIG. 6 shows a flowchart of a method for generating a reference voltage according to a fourth embodiment of the present invention. As shown in FIG. 6, in step 610, a plurality of initial currents with different temperature coefficients are generated. For details, for example, refer to how the bandgap reference circuits of the first to third embodiments above generate currents I1 and I2, here No restatement. Then, in step 620, these initial currents are copied and synthesized into a synthesized current, and the synthesized current is converted into one or more reference voltages. For details, for example, reference can be made to reference voltage generation in the above-mentioned first to third embodiments. How the circuit performs current mirroring and conversion to generate a reference voltage with zero temperature coefficient will not be repeated here. Next, in step 630, one or more bias currents are respectively generated according to at least one of these initial currents. For details, for example, please refer to how the bias current source circuit performs current mirroring in the above-mentioned first to third embodiments. One or more bias currents are copied, which will not be repeated here. Next, in step 640, the one or more bias currents are converted into one or more differential voltages to be respectively added to one of the reference voltages to form one of the one or more output reference voltages, the details of which For example, reference can be made to how the regulated output circuit converts the reference voltage and the one or more bias currents into one or more output reference voltages with different temperature coefficients in the above-mentioned first to third embodiments, which will not be repeated here. the

To sum up the above, compared with the prior art, the above-mentioned embodiment performs subsequent processing by taking out the current of the bandgap reference circuit instead of the voltage, so there is no need to use a plurality of buffers, so that it can have small area, low power consumption, It has the advantages of simple structure and accurate temperature coefficient. In addition, the bias current can be synthesized by subtracting the currents, which can increase the temperature coefficient of the bias current. As a result, a smaller variable resistance can be used to obtain the output reference voltage in the required range, and the reference voltage with zero temperature coefficient can be widened. input range. In addition, the bias current can be switched between different temperature coefficients by switching the current path, so the output reference voltage can be switched between different temperature coefficients, so that it can be applied to various occasions. the

To sum up, although the present invention has been disclosed above with preferred embodiments, they are not intended to limit the present invention. Those skilled in the technical field to which the present invention belongs may make various equivalent changes or substitutions without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be as defined by the appended claims of the application. the

Claims (21)

1. A reference voltage generating circuit, characterized in that, comprising: a bandgap reference circuit generating multiple initial currents with different temperature coefficients; a reference voltage generating circuit, coupled to the bandgap reference circuit, for replicating these initial currents and synthesizing them into a synthesized current, and converting the synthesized current into one or more reference voltages; a bias current source circuit, coupled to at least one of the bandgap reference circuit and the reference voltage generation circuit, for generating one or more bias currents according to at least one of the initial currents; and One or more regulated output circuits, each of which is coupled to the reference voltage generating circuit to receive a corresponding one of the one or more reference voltages, and coupled to the bias current source circuit to receive the one or more A corresponding one of the plurality of bias currents is used to convert the received bias current into an individual differential voltage to be added to the reference voltage to form an individual output reference voltage. 2. The reference voltage generating circuit according to claim 1, wherein the initial currents include a first current with a positive temperature coefficient and a second current with a negative temperature coefficient. 3. The reference voltage generating circuit according to claim 2, wherein the bandgap reference circuit comprises: a current generating circuit proportional to absolute temperature for generating the first current; and A voltage-to-current conversion circuit is coupled to a node of the proportional-to-absolute-temperature current generating circuit for converting a voltage at the node into the second current. 4. The reference voltage generation circuit according to claim 1, wherein the bias current source circuit comprises one or more mirror transistors, coupled to the bandgap reference circuit and the reference voltage generation circuit At least one is used to replicate at least one of the initial currents to serve as at least one of the one or more bias currents respectively. 5. The reference voltage generation circuit according to claim 1, wherein the bias current source circuit comprises a current synthesis circuit coupled to at least one of the bandgap reference circuit and the reference voltage generation circuit for use in At least two of the initial currents are copied and synthesized into at least one of the one or more bias currents. 6. The reference voltage generating circuit according to claim 5, wherein the current synthesis circuit further comprises a plurality of switching elements for switching on different current paths of the current synthesis circuit to synthesize different current components, so as to switch the temperature coefficient of the bias current. 7. The reference voltage generation circuit according to claim 2, wherein the one or more bias currents generated by the bias current source circuit are respectively equal to the first current, the second current, the second current One of an added value of a current and the second current, and a subtracted value of the first current and the second current. 8. The reference voltage generating circuit according to claim 2, wherein the reference voltage generating circuit adds the replicated first current and the second current to form the composite with a substantially zero temperature coefficient current, and converting the resultant current to the one or more reference voltages having a substantially zero temperature coefficient. 9. The reference voltage generating circuit according to claim 1, wherein the reference voltage generating circuit comprises: A mirroring circuit, including a plurality of mirroring transistors, these mirroring transistors are coupled in parallel with each other, and the gate of each of them is coupled to the energy bandgap reference circuit, so as to respectively replicate these initial currents and concatenate them into the synthetic current; and A resistive element is used to convert the synthesized current into the one or more reference voltages. 10. The reference voltage generation circuit according to claim 9, characterized in that the reference voltage generation circuit comprises one or more multiplexers, each of which is coupled to the resistance element for selecting the resistance element The resistance value is used to adjust one of the one or more reference voltages. 11. The reference voltage generating circuit according to claim 1 , wherein each of the one or more regulated output circuits comprises: a resistance element coupled between the bias current source circuit and an output node; an output transistor coupled to the output node; and An operational amplifier having a first input terminal coupled to one of the one or more reference voltages of the reference voltage generating circuit, a second input terminal coupled to the resistive element, and an output terminal coupled to the A gate of the output transistor. 12. A method for generating a reference voltage, comprising: Generate multiple initial currents with different temperature coefficients; copying and synthesizing these initial currents into a composite current, and converting the composite current into one or more reference voltages; generating one or more bias currents respectively according to at least one of the initial currents; and The one or more bias currents are converted into one or more differential voltages to be added to one of the reference voltages to form one of the one or more output reference voltages. 13. The reference voltage generation method according to claim 12, wherein the initial currents include a first current with a positive temperature coefficient and a second current with a negative temperature coefficient. 14. The reference voltage generation method according to claim 13, wherein the step of generating a plurality of initial currents with different temperature coefficients comprises: generating the first current; and Converting a node voltage generated during the process of generating the first current into the second current. 15. The method for generating a reference voltage according to claim 12, wherein the step of generating the one or more bias currents comprises duplicating at least one of the initial currents as the one or more bias currents respectively at least one. 16. The reference voltage generation method according to claim 12, wherein the step of generating the one or more bias currents comprises copying at least two of the initial currents and synthesizing them into the one or more bias currents. at least one of the piezoelectric currents. 17. The method for generating a reference voltage according to claim 16, wherein the step of synthesizing the replicated initial currents into one of the one or more bias currents comprises switching between different current paths to synthesize different current components to switch the temperature coefficient of the bias current. 18. The reference voltage generation method according to claim 13, wherein each of the one or more bias currents is equal to the first current, the second current, the first current and the second current One of the added value of the current and the subtracted value of the first current and the second current. 19. The reference voltage generating method according to claim 13, wherein the step of generating the one or more reference voltages comprises summing the replicated first current and the second current to have a value substantially zero temperature coefficient of the resultant current, and converting the resultant current into the one or more reference voltages having a substantially zero temperature coefficient. 20. The reference voltage generation method according to claim 12, wherein the step of generating the one or more reference voltages comprises: copy and combine these initial currents into the composite current; and The resultant current is converted to the one or more reference voltages using a resistive characteristic. 21. The reference voltage generation method according to claim 20, wherein the step of converting the resultant current into the one or more reference voltages using the resistance characteristic comprises performing one or more multiplexing processes to select The resistance value of the resistance characteristic adjusts the voltage level of the one or more reference voltages.

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