JP5731897B2 - Electronic volume - Google Patents

Description

  The present invention relates to an improvement in characteristics of an electronic volume, in particular, an electronic volume of a type in which a resistance is selected using a mechanical switch.

  FIG. 5 shows a circuit configuration of a conventional weighted (method) electronic volume. This electronic volume circuit is arranged in order with respect to the signal input terminal 1, for example, a resistance group 2 including resistors R21 to R28, A switch group 3 composed of switches S31 to S38 for switching the resistance (voltage dividing point) of the resistor group 2, a resistor group 4 composed of resistors R41 to R48, and a switch composed of switches S51 to S58 for switching the resistance of the resistor group 4 A group 5 and a buffer amplifier 6 are connected, and a signal output terminal 7 is connected to the buffer amplifier 6.

  In the above circuit, the resistor group 2 and the switch group 3 form a first attenuator, and the resistor group 4 and the switch group 5 form a second attenuator. For example, the first attenuator Attenuation in a desired range is realized in 1 dB steps by setting an attenuation that changes in units, for example, -8 dB, and an attenuation that changes in units larger than -1 dB in the second attenuator. Can do. In the circuit configuration of the electronic volume, when a MEMS (Micro Electro Mechanical System) switch, which is a mechanical switch, is employed as the switches S31 to S38 and S51 to S58, high performance with low distortion and low noise is expected. Is done.

JP 2005-184055 A

  However, in the case of using mechanical switches as the switches S31 to S38 and S51 to S58 as in the electronic volume of FIG. 5, since there are hysteresis characteristics, there are variations in the voltage at which the switch is turned on and the voltage at which it is turned off (response Variation), and may be opened instantaneously, which causes a problem of pop noise. In contrast to the momentary opening described above, there may be a method that does not create this state by controlling the switch control time. In this case, however, there is a time (on resistance) when two switches are turned on at the same time. Depending on the situation, the volume change may be uncomfortable.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electronic volume that can eliminate variations in responses when switching mechanical switches and the occurrence of pop sounds due to instantaneous open states. It is to provide.

In order to achieve the above object, the invention according to claim 1 includes an attenuator comprising a resistor group and a mechanical switch group for selecting a resistance of the resistor group, and supplies a signal from the attenuator to the amplifier. In the electronic volume, the electronic switch is connected in parallel to each switch of the mechanical switch group, the electronic switch is turned on before the mechanical switch, and after the mechanical switch. Control is made to turn off.
The invention according to claim 2 is characterized in that a MEMS switch is used as the mechanical switch.

  According to the above configuration, for example, a MEMS switch is disposed as a mechanical switch in a weighted circuit including, for example, a first attenuator and a second attenuator, and the MEMS switch serves as an electronic switch. The MOS switches are connected in parallel. For example, the MOS switches are turned on at an earlier timing than the MEMS switches, and are turned off at a later timing than the MEMS switches.

  According to the electronic volume of the present invention, even if there is a hysteresis characteristic of the mechanical switch (MEMS switch), the mechanical switch is turned on after the electronic switch (MOS switch) is turned on first. Switching can be performed in a timeless manner, and since the electronic switch does not vary in response speed, pop noise can be eliminated. In addition, since the high-speed switch operation can be performed by the electronic switch, there is no time for the two switches to be turned on at the same time.

Furthermore, in the weighted circuit, since the distortion of the switch of the first attenuator does not appear without increasing the resistance of the second attenuator, low distortion and low noise can be achieved with an attenuation accuracy without fluctuation. The operation can be realized.
In addition, since the MOS switch can be a small switch with a minimum rule, there are advantages such that the mounting area in the chip can be reduced and the influence of pop noise due to the influence of parasitic capacitance is reduced.

  Further, when a MEMS switch is used as a mechanical switch, there is an advantage that not only low distortion and low noise can be realized, but also miniaturization is possible.

It is a circuit diagram which shows the structure of the electronic volume (weighting type) based on 1st Example of this invention. FIG. 2 is a configuration diagram [FIG. (A)] of a set of switches and an operation diagram [FIGS. It is a figure which shows operation | movement of 2 sets of switches of an Example. It is a circuit diagram which shows the structure of the electronic volume (ladder type) of 2nd Example. It is a circuit diagram which shows the structure of the conventional electronic volume (weighting type).

  FIG. 1 shows the configuration of a weighted electronic volume according to the first embodiment of the present invention. In this embodiment, as in the case of FIG. 2 and a first attenuator comprising a switch group 30 and a second attenuator comprising a resistor group 4 and a switch group 50 are connected in series, and the output side of the switch group 50 is connected to a signal output terminal via a buffer amplifier 6. Connected. As the resistor group 2, for example, resistors R21 to R28 are connected in series between the signal line and the ground, and the MEMS is a mechanical switch so that each connection point (voltage dividing point) of these resistors R21 to R28 can be switched and selected. (Micro Electro Mechanical System) switches S31a to S38a are connected, and MOS (Metal-Oxide-Semiconductor) switches S31b to S38b as electronic switches are connected in parallel to the MEMS switches S31a to S38a.

  Further, as the resistor group 4, for example, resistors R41 to R48 are connected in series between the signal line and the ground, and the MEMS switches S51a to S51a are configured so that the connection points (voltage dividing points) of these resistors R41 to R48 can be switched and selected. S58a is connected, and MOS switches S51b to S58b as electronic switches are connected in parallel to the MEMS switches S51a to S58a.

  2B and 2C show the operation of a set of switches 31a and 31b in FIG. 2A for selecting the resistance of the resistor group 2, for example. The MOS switch 31b is a MEMS switch. Control is performed so that the switch 31a is turned on at an earlier timing than the switch 31a is turned on and turned off at a later timing than the MEMS switch 31a is turned off.

Embodiment has the above configuration, for example, in the first attenuator resistor group 2 of FIG. 1, after selecting the connection point e ₁ between the signal line resistor R21, to the connection point e ₂ of the resistor R21 resistor R22 to switch, as shown in (a) ~ (D) of FIG. 3, first, to turn on the MOS switches S31b of electronic, by subsequently turning on the MEMS switch 31a of the mechanical type, the connection point _{e 1} is selected, the time switch, and at the same time to turn off the MOS switch 31b after turning off the MEMS switches 31a, the MOS switch 32b is turned on, then, by turning on the MEMS switch 32a, the connection point _{e 2} is selected. Further, even when canceling the selection of the connection point _{e 2,} to turn off the MOS switch 32b after turning off the MEMS switch 32a. Such a switch operation is similarly performed in the second attenuator, and the MOS switches 51b to 58b of the switch group 50 are turned on at an earlier timing than the MEMS switches S51a to 58a and turned off at a later timing. The resistance of the resistance group 4 is selected.

  According to such a configuration and operation, the influence of the hysteresis characteristics of the mechanical MEMS switches S31a to S38a, S51a to S58a and the influence due to the variation in response speed are eliminated, and the instantaneous effect that has occurred in the mechanical switch. It is possible to reduce the occurrence of pop sounds without opening time. Further, since the high-speed switch operation is performed by the electronic MOS switches S31b to S38b, S51b to S58b, there is no time for the two switches to be turned on at the same time, and no audible discomfort is caused even if the volume is changed. . That is, the advantages of the mechanical (MEMS) switch and the electronic (MOS) switch can be utilized.

  Furthermore, in the circuit of the first embodiment, it is not necessary to increase the resistance value of the resistance group 4 of the second attenuator, and the attenuation accuracy varies depending on the ON resistance of the MEMS switches S31a to S38 of the first attenuator. Since there is no occurrence of distortion of the MEMS switches S31a to S38a, there is an advantage that low distortion can be realized. Further, since a small MOS switch is used, the mounting area in the chip can be reduced and the influence of charge injection is also reduced.

  FIG. 4 shows the configuration of a ladder type electronic volume according to the second embodiment. In this embodiment, a resistor group 8 consisting of resistors R81 to R88 is connected between the signal line and the ground, and the resistor R87. And R88 are connected in series to resistors R91 to R98 of the resistor group 9. Then, mechanical MEMS switches S31a to S38a and S51a to S58a are connected so that the connection points of the resistors of these resistor groups 8 and 9 can be switched and selected, and the MEMS switches S31a to S38a and S51a to S58a are connected. Electronic MOS switches S31b to S38b (switch group 30) and S51b to S58b (switch group 50) are connected in parallel with each other.

  In the second embodiment, similarly to the first embodiment, the MOS switches S31b to S38b and the MOS switches 51b to 58b of the switch group 30 are replaced by the MEMS switches S31a to S38a and the MEMS switches S51a to 58a of the switch group 50. By turning on at an early timing and turning off at a late timing, the connection point of each resistor in both resistance groups 8 and 9 is selected, and the effect of hysteresis characteristics, the effect of variation in response speed, and the instantaneous open time As a result, the occurrence of pop sounds can be reduced.

  In the above embodiment, the MEMS switch is used as the mechanical switch. However, other mechanical switches can be applied, and the MOS switch is used as the electronic switch. However, other transistor switches may be applied.

2, 4, 8, 9 ... resistance group,
3, 5, 30, 50 ... switch group,
6 ... buffer amplifier,
R21 to R28, R41 to R48, R81 to R88, R91 to R98 ... resistors,
S31-S38, S31a-S38a ... MEMS switch,
S51-S58, S51a-S58a ... MEMS switch,
S31b-S38b ... MOS switch,
S51b to S58b: MOS switches.

Claims (2)

In an electronic volume comprising an attenuator comprising a resistor group and a mechanical switch group for selecting the resistance of the resistor group, and supplying a signal from the attenuator to the amplifier,
Said connecting an electronic switch in parallel with respect to each of the switches of the mechanical type switches, the electronic switch is turned on earlier than the mechanical switch, and performs control so as to turn off later than the mechanical switch that Features an electronic volume.   2. The electronic volume according to claim 1, wherein a MEMS switch is used as the mechanical switch.

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