JP2005079925A - High output dc amplifier circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire a high voltage DC output by a simple constitution. <P>SOLUTION: Push-side and pull-side electric field effect transistors connected to positive and negative high voltage power sources via push-side and pull-side photocouplers are driven by amplification voltage outputs of input arithmetic amplifier circuits for amplifying voltage inputs. Consequently, a processing circuit connected to the high voltage power source is simplified, and high output DC amplifier circuits with excellent pressure-proof characteristics are acquired. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-output DC amplifier circuit, and is particularly suitable for application when obtaining a high-voltage DC output.

  Conventionally, as this type of high-output DC amplifier circuit, a configuration as shown in FIG. 5 has been proposed (see Non-Patent Document 1).

  The high output DC amplifier circuit 1 receives a voltage input V1 applied between the ground side input terminal T11 and the hot side input terminal T12 at the non-inverting input terminal of the input operational amplifier circuit 2 via the input resistor R1, and outputs the amplified voltage. V2 is applied to a level shift circuit 4 constituted by a push side shift transistor 3A made of an NPN transistor and a pull side shift transistor 3B made of a PNP transistor.

  The emitter resistors R4 and R5 of the transistors 3A and 3B are connected to each other, the collector of the transistor 3A is connected to the positive high-voltage power supply + Vcc via the voltage dividing resistors R6 and R8, and the connection midpoint of the resistors R6 and R8 is a PNP transistor. To the base of the push side drive transistor 5A.

  Similarly, the collector of the transistor 3B of the level shift circuit 4 is connected to the negative high voltage power source -Vcc via the voltage dividing resistors R7 and R9, and the connection middle point is the base of the pull side drive transistor 5B which is an NPN transistor. Connected.

  The drive transistors 5A and 5B are connected between the bias circuit 6 and the positive and negative high-voltage power supplies + Vcc and −Vcc, respectively, and their collector-side output terminals respectively constitute a push-pull output stage 7 and a pull-side output stage 7 The side field effect transistors 8A and 8B are connected to the gates.

  The field effect transistors 8A and 8B connected in series with each other are constituted by N-channel and P-channel field effect transistors (referred to as N-channel and P-channel FET), respectively, and both ends on the drain side are positive and negative high-voltage power supplies + Vcc and The source-side common connection end is connected to the hot-side output terminal T22, thereby sending the output voltage V3 to the ground-side output terminal T21.

  The hot-side output terminal T22 is connected to the non-inverting input terminal of the input operational amplifier circuit 2 via a feedback resistor R2 (having a resistance ratio of R1: R2 = 1: 100 with respect to the input resistor R1). Thus, when the voltage input V1 changes, an output voltage V3 that changes following this change is obtained.

  In FIG. 5, when a voltage input V1 between −1 and +1 [V] is applied between the input terminals T11 and T12, the potential difference between the amplified voltage output V2 of the corresponding voltage value and the high voltage power supplies + Vcc and −Vcc. Is obtained between the emitters and collectors of the drive transistors 5A and 5B, and the impedances of the push-side and pull-side field effect transistors 8A and 8B are controlled by this control voltage output, whereby the output terminal T21. And a voltage output V3 = -100 to +100 [V] having a resistance ratio R2 / R1 (= 100) times the voltage input V1 = -1 to +1 [V] between T22 and T22.

Incidentally, when the potential of the amplified voltage output V2 is increased by increasing the potential of the voltage input V1, the control output voltage is increased and decreased by decreasing and increasing the base potential of the drive transistors 5A and 5B, respectively. As a result, the impedances of the push-side and pull-side field effect transistors 8A and 8B decrease and increase, respectively, and the potential of the voltage output V3 increases or decreases, and as a result, the voltage output V3 changes according to the change of the voltage input V1. .
Published by Masaomi Suzuki, “Design of the Sadamoto, Sequel, Transistor Circuit”, page 136, CQ Publishing Co., Ltd., July 9, 1998, 9th edition.

  According to the above configuration, the input operational amplifier circuit 2 that processes a voltage input of a low voltage of about −1 to +1 [V] and the push that processes a voltage output V3 of a high voltage of about −100 to +100 [V]. Since the processing with the pull output stage 7 is configured using NPN and PNP transistors, a complicated circuit configuration with a large number of circuit elements is required, and the NPN and PNP transistors have high breakdown voltage. Therefore, there is a problem that a high voltage output of a higher voltage (for example, about several thousand [V]) cannot be obtained with a simple configuration as the voltage output V3.

  The present invention has been made in consideration of the above points, and an object of the present invention is to propose a high-output DC amplifier circuit which can obtain a required high voltage output with a simple configuration as much as possible.

  In order to solve such a problem, in the present invention, the input operational amplifier circuit 12 that amplifies the voltage input V11 and the amplified voltage output V12 of the input operational amplifier circuit 12 are received by the light emitting element LD and the output of the light receiving element PAR is pushed. Push-side photocoupler 13A and pull-side photocoupler 13B that output as the side-side photocoupler output V14 and the pull-side photocoupler output V15, and the push-side connected in series between the positive-side high-voltage power supply + Vcc and the negative-side high-voltage power supply -Vcc A push-pull output stage 15 that has a field effect transistor 16A and a pull-side field effect transistor 16B, sends a voltage output V13 from the connection midpoint, and feeds back the connection midpoint to the input terminal of the input operational amplifier circuit 12; The push-side photocoupler 13A and the pull-side photocoupler 13B The element PAR is configured to receive the light emitted from the light emitting element LD by a photodiode array PAR having a plurality of photodiodes PD1 to PDN connected in series with each other, and by the push side photocoupler output V14 of the push side photocoupler 13A. The push-side field effect transistor 16A is controlled, and the pull-side field effect transistor 16B is controlled by the pull-side photocoupler output V15 of the pull-side photocoupler 13B.

  Further, in the present invention, the input operational amplifier circuit 12 that amplifies the voltage input V11, and the amplified voltage output V12 of the input operational amplifier circuit 12 is received by the light emitting element LD, and the output of the light receiving element PT is respectively sent to the push side photocoupler output V24. The push-side photocoupler 31A and the pull-side photocoupler 31B that are sent out as the pull-side photocoupler output V25, and the push-side field effect transistor 16A connected in series between the positive high-voltage power supply + Vcc and the negative high-voltage power supply -Vcc. A push-pull output stage 15 having a pull-side field effect transistor 16B, sending a voltage output V23 from the connection midpoint, and feeding back the connection midpoint to the input terminal of the input operational amplifier circuit 12, and a first floating power supply 36 and the push-side photocoupler of the push-side photocoupler 31A. A push-side drive circuit 32A that has a first current amplification type operational amplifier circuit 35 that obtains a push-side control output based on the first output V24, and that controls the push-side field effect transistor 16A by the push-side control output; And a second current amplification type operational amplifier circuit 35 that obtains a pull-side control output based on the pull-side photocoupler output V25 of the pull-side photocoupler 31B. A pull side drive circuit 32B for controlling the side field effect transistor 16B is provided.

  According to the present invention, the high voltage circuit is separated from the low voltage circuit by a photocoupler and can be configured by a high breakdown voltage field effect transistor, thereby having a sufficiently high driving voltage with a simpler configuration. It is possible to realize a high-output DC amplifier circuit that can control the controlled object.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) First Embodiment In FIG. 1, reference numeral 11 denotes a high output DC amplification circuit as a whole, and a voltage input V11 applied between a ground side input terminal T31 and a hot side input terminal T32 is connected via an input resistor R21. The input operational amplifier circuit 12 is input to the inverting input terminal, and the amplified voltage output V12 is input to the push-side photocoupler 13A and the pull-side photocoupler 13B.

  The photocouplers 13A and 13B connect the infrared light-emitting photodiode LD to the input terminals P1 and P2, and output a photodiode array PAR formed by connecting a plurality of photodiodes PD1, PD2,... PDN in series to the output terminals P3 and P4. It has the structure connected between.

  The anode of the infrared light emitting diode LD of the push-side photocoupler 13A is supplied with the amplified voltage output V12 via the input terminal P1, and the cathode is supplied to the negative power source of the bias circuit 14 via the input terminal P2 and the load resistor R23 in this order. 14A.

  An amplified voltage output V12 is applied to the cathode of the infrared light emitting diode LD of the pull-side photocoupler 13B through the input terminal P2, and the anode is connected to the positive terminal of the bias circuit 14 through the input terminal P1 and the load resistor R24 sequentially. Connected to power supply 14B.

  Thus, a current corresponding to the potential difference between the amplified voltage output V12 and the negative power source 14A flows through the infrared light emitting diode LD of the push-side photocoupler 13A. When a current corresponding to the potential difference between the amplified voltage output V12 and the positive power supply 14B flows through the infrared light emitting diode LD of the photocoupler 13B, infrared light having a corresponding amount of light is emitted.

  The photocoupler outputs V14 and V15 of the output terminals P3 and P4 of the push-side and pull-side photocouplers 13A and 13B are the control voltage outputs of the push-side and pull-side field effect transistors 16A and 16B constituting the push-pull output stage 15, respectively. The gate and source resistors R25 and R26 are connected to each other, whereby the impedance of the push-side and pull-side field effect transistors 16A and 16B is a value corresponding to the amount of infrared light received by the push-side and pull-side photodiode array PAR, respectively. To control.

  In this case, the push-side field effect transistor 16A is composed of an N-channel field effect transistor (ie, N-channel FET), whereas the pull-side field effect transistor 16B is a P-channel field effect transistor (ie, P-channel FET). Thus, the push-pull output stage 15 is constituted by a complementary circuit.

  The push-pull output stage 15 connects a series circuit of a push-side field effect transistor 16A, source resistors R25 and R26, and a pull-side field effect transistor 16B between a positive side high-voltage power source + Vcc and a negative side high-voltage power source -Vcc, and a source resistor R25. And the connection midpoint of R26 is connected to the hot-side output terminal T42, whereby the voltage output V13 is sent between the ground-side output terminal T41 and the hot-side output terminal T42.

  The hot-side output terminal T42 is connected to the inverting input terminal of the input operational amplifier circuit 12 via the feedback resistor R22, whereby the resistance ratio between the feedback resistor R22 and the input resistor R21 (in this embodiment, R21: R22). = 1: 100 = 1/100), the voltage output V13 is fed back, and when the voltage input V11 changes, the voltage output V13 can be changed to follow this.

  In the above configuration, when the potential of the amplified voltage output V12 of the input operational amplifier circuit 12 rises due to a decrease in the voltage input V11 input to the input terminals T31 and T32, the input terminals P1 and P2 of the push-side photocoupler 13A. The voltage between the output terminals P3 and P4 increases as the current value between them increases, and the voltage between the output terminals P3 and P4 decreases as the current value between the input terminals P1 and P2 of the pull-side photocoupler 13B decreases. Falls.

  At this time, the potential at the midpoint of connection between the source resistors R25 and R26 of the push-side and pull-side field effect transistors 16A and 16B rises, so that the voltage input V11 of the input terminals T31 and T32 becomes V11 = −1 to +1 [ V], the voltage output V13 of the output terminals T41 and T42 changes accordingly between V13 = −100 to +100 [V].

  In this connection, the voltage output V13 is fed back to the non-inverting input terminal of the input operational amplifier circuit 12 via the feedback resistor R22, so that the voltage output V13 changes in accordance with the change in the voltage input V11.

  According to the above configuration, a high voltage output V13 that changes in response to the voltage input V11 can be obtained. In this way, the amplified voltage output V12 of the input operational amplifier circuit 12 is converted to the push-side photocoupler 13A. And push-side and pull-side field effects of high withstand voltage constituting a high-voltage circuit separated from the low-voltage circuit by transmitting to the photodiode array PAR via the optical output of the infrared light-emitting diode LD of the pull-side photocoupler 13B Since the transistors 16A and 16B can be controlled, voltage transmission from the low voltage circuit to the high voltage circuit can be realized by a simple circuit configuration with a small number of elements.

  In addition to this, even when a capacitive load such as the piezo element 17 is driven by the voltage output V13, the push-side field effect transistor 16A and the pull-side field effect are used to inject and withdraw charges from the capacitive load. The high-voltage power supply + Vcc and the negative high-voltage power supply −Vcc can be operated at a high speed via the transistor 16B, whereby the driving operation of the piezo element 17 can be speeded up.

(2) Second Embodiment FIG. 2 shows a second embodiment, and the push-pull output stage 15 of FIG. 1 is complementary as shown in FIG. In the case of FIG. 2, the pull-side field effect transistor 16BX is configured using an N-channel FET in the case of FIG. 2, and the output terminals P3 and P4 of the pull-side photocoupler 13B are connected to the gate and source resistance R26X, respectively. Other than the above, the other configuration is the same as in FIG.

  According to the configuration shown in FIG. 2, driving control outputs for the push-side and pull-side field effect transistors 16A and 16BX are obtained from the photocouplers 13A and 13B, thereby driving both N-channel and P-channel FETs. As a result of the control, even if the pull-side field effect transistor 16BX is configured not to be complementary to the push-side field effect transistor 16A but using the same N-channel FET, the pull-side photocoupler 13B The pull operation can be performed by the output, and as a result, the withstand voltage characteristic of the push-pull output stage 15 can be further enhanced.

  In general, the breakdown voltage of the P-channel FET is lower than the breakdown voltage of the N-channel FET. Therefore, when the N-channel FET and the P-channel FET are combined as the push-pull output stage 15 as shown in FIG. The breakdown voltage characteristic cannot be increased to the N-channel FET by being determined by the P-channel FET.

  On the other hand, in any of the cases shown in FIG. 2, an N-channel FET having a high breakdown voltage can be used in combination, so that the breakdown voltage characteristic of the push-pull output stage 15 can be increased to the breakdown voltage characteristic of the N-channel FET.

(3) Third Embodiment FIG. 3 shows a third embodiment. As shown in FIG. 1, parts corresponding to those in FIG. A second push-side field effect transistor 16AY for expanding the breakdown voltage composed of an N-channel FET is connected in cascade between the positive-side high-voltage power supply + Vcc, and a pull-side field effect transistor 16B composed of a P-channel FET and a negative-side high-voltage The second pull-side field effect transistor 16BY for expanding the breakdown voltage, which is a P-channel FET, is connected in cascade with the power source -Vcc.

  As a drive circuit for the second push-side field effect transistor 16AY, voltage-dividing resistors R31 and R32 are connected in series between the source resistor R25 of the push-side field effect transistor 16A and the positive high-voltage power supply + Vcc, and the connection midpoint Is connected to the gate of the second push-side field effect transistor 16AY.

  Similarly, as a drive circuit for the second pull-side field effect transistor 16BY, voltage-dividing resistors R33 and R34 are connected in series between the source resistor R26 of the pull-side field effect transistor 16B of FIG. 1 and the negative-side high-voltage power supply -Vcc. It has a configuration similar to that of connecting and connecting the midpoint of connection to the gate of the second pull-side field effect transistor 16BY.

  In the above configuration, the second field effect transistors 16AY and 16BY are turned off because no power is supplied to the sources when the field effect transistors 16A and 16B are turned off, whereas the field effect transistors 16A and 16BY are turned on. When each of 16B is turned on, the operation power is supplied to the source through this, whereby the second push-side field effect transistors 16AY and 16BY are turned on.

  At this time, the gates of the second push-side and pull-side field effect transistors 16AY and 16BY are constantly supplied with a divided voltage, so that the impedance becomes a constant value. On the other hand, the push-side and pull-side field effect transistors The impedances of 16A and 16B are controlled by the control voltage outputs V14 and V15 of the push-side and pull-side photocouplers 13A and 13B, respectively, so that the voltage output V13 becomes a value corresponding to the voltage input V11.

  According to the configuration of FIG. 3, the four field effect transistors, that is, the push-side field effect transistors 16A and 16AY and the pull-side field effect transistors 16B and 16BY share the breakdown voltage, so that each field effect transistor is easily available. Even if the FET has a breakdown voltage characteristic, the push-pull output stage 15 having a high breakdown voltage characteristic (a voltage output V13 of several thousand [V] can be output) can be configured as a whole.

(4) Fourth Embodiment FIG. 4 shows a fourth embodiment. As shown in FIG. 4, the same reference numerals are given to the corresponding parts to those in FIG. Applies when driving things.

  In this case, the amplified voltage output V12 of the input operational amplifier circuit 12 is supplied to the infrared light emitting diodes LD of the push side photocoupler 31A and the pull side photocoupler 31B.

  The photocouplers 31A and 31B receive, in one phototransistor PT, when infrared light having a light amount corresponding to the amplified voltage output V12 applied between the input terminals P11 and P12 is emitted in the infrared light emitting diode LD, The photocoupler outputs V24 and V25 are supplied to push side and pull side drive circuits 32A and 32B via output terminals P13 and P14, respectively.

  Each of the push side and pull side drive circuits 32A and 32B has a current amplification type operational amplifier circuit 35, and an input voltage V24 applied to the non-inverting input terminal by the positive and negative power sources 36A and 36B of the floating power source 36 and Voltage outputs V26 and V27 corresponding to V25 are supplied between the gate and source of the push-side and pull-side field effect transistors 16A and 16B of the push-pull output stage 15.

  A driving current flows from the positive power source 36A of the floating power source 36 through the output terminal P13, the phototransistor PT, the output terminal P14, the input resistor R27, and the power source midpoint loop of the floating power source 36 to the phototransistor PT of the photocouplers 31A and 31B. The drive current is controlled in accordance with the amount of infrared light applied to the phototransistor PT from the light emitting diode LD, so that the operational amplifier circuit 35 is non-inverted as outputs of the photocouplers 31A and 31B at both ends of the input resistor R27. Input voltages V24 and V25 to the input terminal are generated.

  The power supply midpoint of the floating power supply 36 of the push side drive circuit 32A is connected to the source resistor R25 of the field effect transistor 16A, and the output terminal of the operational amplifier circuit 35 is connected to the gate of the field effect transistor 16B. The field effect transistor 16A is driven and controlled by the voltage output V26 between the output terminals of the operational amplifier circuit 35.

  The power supply midpoint of the floating power supply 36 of the pull side drive circuit 32B is connected to the gate of the field effect transistor 16B, and the output terminal of the operational amplifier circuit 35 is connected to the source resistor R26 of the field effect transistor 16B. The field effect transistor 16B is driven and controlled by the voltage output V27 between the point and the output terminal of the operational amplifier circuit 35.

  In the above configuration, when the potential of the voltage input V11 decreases and the potential of the amplified voltage output V12 obtained at the output terminal of the input operational amplifier circuit 12 increases, the amount of light emitted from the light emitting diode LD of the push-side photocoupler 31A increases. In contrast, the light emission amount of the light emitting diode LD of the pull side photocoupler 31B decreases.

  At this time, the potential of the voltage input V24 of the push side drive circuit 32A rises, so that the output voltage of the operational amplifier circuit 35 increases, and as a result, the impedance of the push side field effect transistor 16A of the push pull output stage 15 decreases.

  On the other hand, when the potential of the voltage input V25 of the pull side drive circuit 32B drops, the output voltage of the operational amplifier circuit 35 decreases, and as a result, the impedance of the pull side field effect transistor 16B of the push-pull output stage 15 increases. .

  Thus, as the impedance of the push-side field effect transistor 16A of the push-pull output stage 15 becomes smaller and the impedance of the pull-side field effect transistor 16B becomes larger according to the change of the voltage input V11, the voltage supplied to the piezo element 17 is increased. The potential of the output V13 increases.

  Thus, the piezo element 17 is driven by the voltage output V23 which changes in accordance with the change of the voltage input V11 between the input terminals T31 and T32, but the push side and the gate of the pull side field effect transistors 16A and 16B are pushed. In addition, since a sufficiently large current can be supplied from the current amplification type operational amplifier circuit 35 of the pull side drive circuits 32A and 32B, in order to drive the large-capacity piezo element 17, a sufficiently large gate electrode corresponding to this is provided. Even when the FET including the FET is used as the field effect transistors 16A and 16B, it is possible to inject and extract charges to the field effect transistors 16A and 16B with a sufficient margin, thereby causing the piezo element 17 to input voltage V11 at a sufficiently high speed. Can be operated in response to changes in

  Thus, the push-side drive circuit 32A and the pull-side drive circuit 32B can be driven by using the floating power source 36 separated from the ground power source by the photocouplers 31A and 31B. It is not necessary to apply a high voltage (since the applied voltage is a few volts at most).

  In the above-described embodiment, the embodiment in which the high-output DC amplifier circuit 11 is used as the drive control circuit for the piezoelectric element 17 has been described. However, the control target is not limited to the piezoelectric element, and the high-voltage DC drive is performed. It can be widely applied to devices that require the

  The present invention can be used as a drive control circuit for an element that requires high-voltage direct current drive such as a piezo element.

1 is an electrical connection diagram illustrating a first embodiment of a high-power DC amplifier circuit according to the present invention. It is an electrical connection diagram showing a second embodiment. It is an electrical connection diagram which shows 3rd Embodiment. It is an electrical connection figure which shows 4th Embodiment. It is an electrical connection diagram which shows the conventional structure.

Explanation of symbols

  1, 11... High output DC amplifier circuit, 2, 12... Input operational amplifier circuit, 3A, 3B... Level shift transistor, 4... Level shift circuit, 5A, 5B. Bias circuit, 7, 15... Push-pull output stage, 8A, 8B... Push side, pull side field effect transistor, 13A, 13B... Push side, pull side photocoupler, 14. 16BX: Push side, pull side field effect transistor, 16AY, 16BY: Second push side, pull side field effect transistor, 17: Piezo element, 31A, 31B: Push side, pull side photocoupler, 32A, 32B: Push side, pull side drive circuit, 35: Current amplification type operational amplifier circuit, 36: Floating power supply.

Claims (2)

An input operational amplifier circuit for amplifying the voltage input;
A push-side photocoupler and a pull-side photocoupler that receive the amplified voltage output of the input operational amplifier circuit at the light-emitting element and output the output of the light-receiving element as a push-side photocoupler output and a pull-side photocoupler output, respectively;
A push-side field-effect transistor and a pull-side field-effect transistor that are connected in series between the positive-side high-voltage power source and the negative-side high-voltage power source, send voltage output from the connection midpoint, and A push-pull output stage that feeds back to an input terminal of an input operational amplifier circuit, wherein the push-side photocoupler and the pull-side photocoupler have a plurality of photodiodes connected in series as the light receiving elements. And configured to receive the light emitted from the light emitting element,
The push-side field effect transistor is controlled by the push-side photocoupler output of the push-side photocoupler, and the pull-side field-effect transistor is controlled by the pull-side photocoupler output of the pull-side photocoupler. High output DC amplifier circuit. An input operational amplifier circuit for amplifying the voltage input;
A push-side photocoupler and a pull-side photocoupler that receive the amplified voltage output of the input operational amplifier circuit as a light-emitting element and send the output of the light-receiving element as a push-side photocoupler output and a pull-side photocoupler output, respectively;
A push-side field-effect transistor and a pull-side field-effect transistor that are connected in series between the positive-side high-voltage power source and the negative-side high-voltage power source, send voltage output from the connection midpoint, and A first current amplifier that is connected to a push-pull output stage that feeds back to the input terminal of the input operational amplifier circuit and a first floating power source and obtains a push-side control output based on the push-side photocoupler output of the push-side photocoupler A push-side drive circuit that has a type operational amplifier circuit and controls the push-side field effect transistor by the push-side control output;
A second current amplification type operational amplifier circuit which is connected to a second floating power source and obtains a pull-side control output based on the pull-side photocoupler output of the pull-side photocoupler; And a pull-side drive circuit for controlling the pull-side field effect transistor.

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