WO2017143623A1

WO2017143623A1 - Control device for direct-current output potential of power amplifier

Info

Publication number: WO2017143623A1
Application number: PCT/CN2016/075249
Authority: WO
Inventors: 刘广斌
Original assignee: 广州时艺音响科技有限公司
Priority date: 2016-02-23
Filing date: 2016-03-01
Publication date: 2017-08-31
Also published as: CN105577125B; CN105577125A

Abstract

A control device for a direct-current output potential of a power amplifier. The control device is implemented on the basis of an active temperature control bias circuit. In the active temperature control bias circuit, a direct-current output potential deviation detection circuit detects a direct-current output potential deviation value of the power amplifier, and a temperature control circuit correspondingly heats or cools a voltage regulating circuit according to the detected direct-current output potential deviation value. The voltage regulating circuit correspondingly regulates, according to the heating or cooling of the temperature control circuit, a bias voltage of a device generating a temperature drift in the power amplifier. Accordingly, the bias voltage can be regulated by means of active temperature control, so as to achieve the purpose of controlling the direct-current output potential, self-excitation and transient intermodulation distortion caused by negative feedback in the prior art are avoided, and the performance of an amplifier circuit is improved.

Description

Control device for DC output potential of power amplifier

Technical field

The invention relates to the field of power amplifier control, in particular to a DC output potential control device for a power amplifier, which is based on an active temperature-controlled bias circuit to achieve stability control and performance improvement of a DC output potential of a power amplifier.

Background technique

Due to the temperature drift characteristics of electronic components, especially the significant temperature drift characteristics of semiconductor components, the power amplifier operates at different ambient temperatures, and the self-heating during operation causes the operating temperature of the components to change, which causes the DC output of the power amplifier. The potential changes with temperature, which in turn makes the power amplifier unstable and may even burn out the load. The existing control method for stabilizing the DC output potential of the power amplifier generally uses the negative feedback design of the circuit to achieve the goal. However, this design will bring transient intermodulation distortion, and it is easy to make the circuit self-excited. In order to avoid self-excitation, it is necessary to filter or phase-compensate the signal. However, the filtering and phase compensation are not perfect, and the reduction is also reduced. Amplify the performance of the circuit. The power amplifier with large loop negative feedback design, the back electromotive force generated by the load due to the inductive load enters the input end of the power amplifier through the negative feedback loop, which adversely affects the stability and distortion performance of the output.

Summary of the invention

The object of the present invention is to provide a control device for a DC output potential of a power amplifier by using a negative feedback design of a power amplifier in the prior art to bring transient intermodulation distortion and easily cause self-excitation and performance degradation of the circuit. It adjusts the bias voltage through active temperature control to achieve the purpose of controlling the DC output potential, thereby avoiding transient intermodulation distortion and self-excitation due to negative feedback, and improving the performance of the amplifier circuit.

In order to achieve the above object, a DC output potential control device for a power amplifier according to the present invention includes an active temperature control bias circuit, and the active temperature control bias circuit includes a DC output potential deviation detecting circuit and temperature control. a circuit and a voltage regulating circuit; the detecting end of the DC output potential deviation detecting circuit is connected to the output end of the power amplifier; the output end of the DC output potential deviation detecting circuit is connected to the input end of the temperature control circuit; An output end of the circuit is connected to an input end of the device for generating a temperature drift in the power amplifier; the DC output potential deviation detecting circuit detects a DC output potential deviation value of the power amplifier, and the temperature control circuit is based on the detected DC The output potential deviation value respectively heats or cools the voltage regulating circuit; the voltage regulating circuit adjusts a bias voltage of the device that generates temperature drift in the power amplifier according to heating or cooling of the temperature control circuit.

In a preferred embodiment of the present invention, the DC output potential deviation detecting circuit includes a low pass filtering branch, a reference potential branch, and an operational amplifier branch; an input end of the low pass filtering branch is connected to the power amplifier An output of the low pass filter branch is coupled to a positive input of the operational amplifier branch; an input of the reference potential branch The terminal is grounded, and its output terminal is connected to the negative input terminal of the operational amplifier branch; the output terminal of the operational amplifier branch is connected to the input terminal of the temperature control circuit.

In a preferred embodiment of the present invention, the temperature control circuit includes a reverse voltage protection branch and a temperature control branch connected to each other; and the temperature control branch is corresponding to the detected DC output potential deviation value. The voltage regulator circuit performs heating or cooling.

In a preferred aspect of the present invention, the temperature control circuit includes an infrared heating branch; and the infrared heating branch performs non-contact heating on the voltage regulating circuit according to the detected DC output potential deviation value.

In a preferred embodiment of the present invention, the voltage regulating circuit includes a heat-sensitive device branch and a voltage regulating branch connected to each other; and the temperature control branch is specifically configured according to the detected DC output potential deviation value. The heat-sensitive device branch is heated or cooled; the output of the voltage-regulating branch is coupled to an input of a device in the power amplifier that produces a temperature drift.

In a preferred embodiment of the present invention, in the DC output potential deviation detecting circuit, the low pass filtering branch includes a resistor R23 and a capacitor C5; the reference potential branch includes a resistor R19; and the operational amplifier branch includes a resistor R20 and a capacitor C4. , capacitor C5 and operational amplifier OPAMP;

An input end of the low pass filter branch is connected to an output end of the power amplifier, an output end of the low pass filter branch is connected to a positive input end of the operational amplifier OPAMP; and the resistor R20 and the capacitor C4 are connected in parallel to be negative a feedback branch, an input end and an output end of the negative feedback branch are respectively connected to a negative input end and an output end of the operational amplifier OPAMP; wherein an input end of the resistor R19 is grounded in the reference potential branch, and an output end thereof is connected The input end of the negative feedback branch; the positive power terminal and the negative power terminal of the operational amplifier OPAMP are correspondingly connected to both ends of the DC power supply.

In a preferred embodiment of the present invention, in the temperature control circuit, the reverse voltage protection branch includes a resistor R21, a resistor R27, a Zener diode D1, and a Zener diode D2; and the temperature control branch includes a resistor R22 and a resistor R26. , NPN transistor Q6 and PNP three-stage tube Q7;

The input end of the resistor R21 is connected to the output end of the operational amplifier branch of the DC output potential deviation detecting circuit; the output end of the resistor R21 is connected to the base of the NPN transistor Q6 and the cathode of the Zener diode D1; the input end of the resistor R27 is connected to the DC output potential The output of the operational amplifier branch in the deviation detecting circuit; the output of the resistor R27 is connected to the base of the PNP tertiary tube Q7 and the anode of the Zener diode D2; the anode of the Zener diode D1 and the cathode of the Zener diode D2 are grounded; The input end of R22 is connected to the emitter of NPN transistor Q6, and its output terminal is grounded; the input end of resistor R26 is connected to the emitter of PNP three-stage tube Q7, and its output terminal is grounded; the collector of NPN transistor Q6 and the PNP three-stage tube Q7 The collector corresponds to both ends of the power supply.

In a preferred embodiment of the present invention, in the voltage regulating circuit, the heat-sensitive device branch includes a thermistor NTC1, a thermistor NTC2, a resistor R13, a resistor R14, a resistor R17, and a resistor R18; and the voltage regulating branch includes Current source I, voltage regulator, resistor R12 and capacitor C3; the thermistor NTC1 is in contact with the NPN transistor Q6 or the resistor R22 in the temperature control branch; the thermistor NTC2 and the PNP three-stage tube in the temperature control branch Q7 or resistor R26 is in contact;

The thermistor NTC1 and the resistor R13 are connected in series and connected in parallel with the resistor R14. The two ends of the thermistor NTC1 are connected in parallel with the output terminal of the current source I and the reference electrode of the voltage regulator; the thermistor NTC2 is connected in series with the resistor R17 and the resistor R18 Parallel, parallel and connected to the reference pole of the voltage regulator and the anode of the voltage regulator respectively; the input end of the resistor R12 is connected to the output end of the current source I, and the output end of the resistor R12 is connected to the input of the device which generates the temperature drift in the power amplifier The input end of the capacitor C3 is connected to the output end of the resistor R12, the output end of the capacitor C3 is connected to the negative end of the power supply and the anode of the voltage regulator, and the cathode of the voltage regulator is connected to the output end of the current source I.

In a preferred embodiment of the present invention, in the voltage regulating circuit, the heat-sensitive device branch includes a thermistor PTC1, a thermistor PTC2, a resistor R13, a resistor R14, a resistor R17, and a resistor R18; and the voltage regulating branch includes Current source I, voltage regulator, resistor R12 and capacitor C3; the thermistor PTC2 is in contact with the NPN transistor Q6 or the resistor R22 in the temperature control branch; the thermistor PTC1 and the PNP three-stage tube in the temperature control branch Q7 or resistor R26 is in contact;

The thermistor PTC1 is connected in series with the resistor R13 in parallel with the resistor R14. The two ends of the thermistor PTC1 are connected in parallel with the output terminal of the current source I and the reference pole of the voltage regulator; the thermistor PTC2 is connected in series with the resistor R17 and the resistor R18 Parallel, parallel and connected to the reference pole of the voltage regulator and the anode of the voltage regulator respectively; the input end of the resistor R12 is connected to the output end of the current source I, and the output end of the resistor R12 is connected to the input of the device which generates the temperature drift in the power amplifier The input end of the capacitor C3 is connected to the output end of the resistor R12, the output end of the capacitor C3 is connected to the negative end of the power supply and the anode of the voltage regulator, and the cathode of the voltage regulator is connected to the output end of the current source I.

In one preferred embodiment of the present invention, the device for generating temperature drift in the power amplifier includes any one of a diode, a triode, and a field effect transistor.

Advantageous Effects: The DC output potential control device of the power amplifier proposed by the present invention is implemented based on an active temperature control bias circuit in which a DC output potential deviation detecting circuit detects a DC output of a power amplifier The potential deviation value, the temperature control circuit heats or cools the voltage regulating circuit according to the detected DC output potential deviation value; the voltage regulating circuit adjusts the bias of the device that generates the temperature drift in the power amplifier according to the heating or cooling of the temperature control circuit. Therefore, the present invention can adjust the bias voltage through active temperature control to achieve the purpose of controlling the DC output potential, avoiding the self-excitation caused by the use of negative feedback in the prior art, and improving the performance of the amplifying circuit.

DRAWINGS

1 is a circuit schematic diagram of a control device for a DC output potential of a power amplifier according to an embodiment.

detailed description

The present invention will be further described below in conjunction with the drawings and embodiments in order to facilitate understanding of those skilled in the art.

Typical power amplifier

Referring to Figure 1, the main circuit of a typical power amplifier without large loop negative feedback is shown in Figure 1 "Power amplifier main circuit", where +VCC is a positive voltage, -VCC is a negative voltage, and GND is ground. Volt. The signal is input through port IN, R3 is Input resistance. E2 is a voltage source that provides a bias voltage for transistor Q3. The resistor R1, the resistor R3, the resistor R5, the voltage source E2, the transistor Q3, and the resistor R8 constitute a first-stage voltage amplification. R4 is the input resistor of the second stage voltage amplification, and the second stage voltage amplification is formed by the resistor R2, the transistor Q1, the transistor Q4, and the resistor R16. R9 is the second-stage voltage-amplified load resistor that simultaneously acts as a voltage sample. E1 and E3 are voltage sources that provide bias voltages for FET Q2 and FET Q5. The voltage source E1, the voltage source E3, the field effect transistor Q2, the field effect transistor Q5, the resistor R7, and the resistor R11 constitute a current amplification output stage, and the amplified signal is outputted from the output port OUT. Among them, the device which is prone to temperature drift in the power amplifier includes a transistor Q1, a transistor Q3, a transistor Q4, a field effect transistor Q2, a field effect transistor Q5, etc., and embodiments of the present invention can adjust the bias of these devices which are prone to temperature drift. Voltage. Of course, the circuit structure of the power amplifier in FIG. 1 is only an example, and may be other circuit structures, and devices that are prone to temperature drift in the circuit structure of other power amplifiers may include semiconductor devices such as diodes, transistors, and field effect transistors.

Overall embodiment - active temperature controlled bias circuit

This embodiment will be described by taking an example of adjusting the bias voltage of the transistor Q4 of the power amplifier of FIG.

Specifically, the control device for the DC output potential of the power amplifier according to the embodiment includes an active temperature control bias circuit. As shown in FIG. 1 , the active temperature control bias circuit includes a DC output potential deviation. a detection circuit, a temperature control circuit and a voltage regulation circuit; the detection end of the DC output potential deviation detection circuit is connected to the output terminal OUT of the power amplifier; the output terminal P2 of the DC output potential deviation detection circuit and the temperature control circuit input The temperature control circuit may or may not be in contact with the voltage regulating circuit; the output end of the voltage regulating circuit is connected to the input end of the transistor Q4 in the power amplifier, that is, the base.

The DC output potential deviation detecting circuit detects the DC output potential deviation value of the power amplifier, and the temperature control circuit heats or cools the voltage regulating circuit according to the detected DC output potential deviation value; the voltage regulating circuit is heated according to the temperature control circuit or The refrigeration accordingly adjusts the bias voltage of the transistor Q4.

1. DC output potential deviation detection circuit

In this embodiment, the DC output potential deviation detecting circuit mainly comprises a low pass filtering branch, a reference potential branch and an operational amplifier branch; the input end of the low pass filtering branch is connected to the output end OUT of the power amplifier; low pass filtering The output of the branch is connected to the positive input of the operational amplifier branch; the input of the reference potential branch is grounded, the output of which is connected to the negative input of the operational amplifier branch; the output of the operational amplifier branch is The input of the temperature control circuit is connected. The function of the low-pass filter branch is to filter out the AC portion of the output terminal OUT of the power amplifier, that is, to extract the DC portion.

Specifically, the circuit structure of the DC output potential deviation detecting circuit includes, but is not limited to, as shown in FIG. 1. In FIG. 1, the low pass filtering branch includes a resistor R23 and a capacitor C5; the reference potential branch includes a resistor R19; and an operational amplifier branch Includes resistor R20, capacitor C4, capacitor C5, and op amp OPAMP.

Wherein the input end of the low-pass filter branch composed of the resistor R23 and the capacitor C5 is connected to the output end of the power amplifier OUT, the output terminal is connected to the positive input terminal of the operational amplifier OPAMP; the resistor R20 and the capacitor C4 are connected in parallel to form a negative feedback branch; the resistor R20 is a negative feedback resistor, which can be used for the amplification factor setting of the DC operating point deviation amount; the capacitor C4 Is a negative feedback capacitor, combined with the low-pass filter branch to further reduce the amplification of the AC signal; the input and output terminals of the negative feedback branch are respectively connected to the negative input terminal and the output terminal P2 of the operational amplifier OPAMP; The input end of the resistor R19 in the reference potential branch is grounded, that is, the reference potential is 0 volt, and the output end is connected to the input end of the negative feedback branch; the positive power supply terminal and the negative power supply terminal of the operational amplifier OPAMP are connected to both ends of the DC power supply. +VCC and -VCC.

2, temperature control circuit

In this embodiment, the temperature control circuit mainly includes a reverse voltage protection branch and a temperature control branch connected to each other; the temperature control branch may or may not be in contact with the voltage regulation circuit, that is, voltage regulation The circuit performs contact heating/cooling or non-contact heating/cooling.

For example, the non-contact heating of the voltage regulating circuit may include an infrared heating branch; the infrared heating branch performs non-contact heating on the voltage regulating circuit according to the detected DC output potential deviation value. . However, in this embodiment, the contact heating is mainly used (that is, the temperature control circuit includes the reverse voltage protection branch and the temperature control branch connected to each other) as an example.

Specifically, the circuit structure of the temperature control circuit includes, but is not limited to, as shown in FIG. 1, the reverse voltage protection branch includes a resistor R21, a resistor R27, a Zener diode D1, and a Zener diode D2; the temperature control branch includes a resistor R22, Resistor R26, NPN transistor Q6 and PNP transistor Q7.

The input end of the resistor R21 is connected to the output terminal P2 of the operational amplifier branch in the DC output potential deviation detecting circuit; the output end of the resistor R21 is connected to the base of the NPN transistor Q6 and the cathode of the Zener diode D1; the input end of the resistor R27 is connected to the DC output The output terminal P2 of the operational amplifier branch in the potential deviation detecting circuit; the output terminal of the resistor R27 is connected to the base of the PNP transistor Q7 and the anode of the Zener diode D2; the anode of the Zener diode D1 and the cathode of the Zener diode D2 are grounded The input end of the resistor R22 is connected to the emitter of the NPN transistor Q6, and its output terminal is grounded; the input end of the resistor R26 is connected to the emitter of the PNP tertiary tube Q7, and its output terminal is grounded; the collector of the NPN transistor Q6 and the PNP three-stage tube The collector of Q7 corresponds to both ends of the power supply +VCC and -VCC.

3, voltage regulator circuit

In this embodiment, the voltage regulating circuit includes a heat-sensitive device branch and a voltage regulating branch connected to each other; the heat-sensitive device branch is in contact with the temperature-controlled branch, that is, the temperature-controlled branch can be thermally sensitive The device branch is heated; the output of the voltage regulating branch is connected to the input terminal of the transistor Q4, that is, the base.

Specifically, the circuit structure of the voltage regulating circuit includes, but is not limited to, as shown in FIG. 1. In FIG. 1, the heat-sensitive device branch includes a thermistor NTC1, a thermistor NTC2, a resistor R13, a resistor R14, a resistor R17, and a resistor R18. The voltage regulating branch includes a current source I, a voltage regulator, a resistor R12, and a capacitor C3; the thermistor NTC1 and the NPN transistor Q6 in the temperature control branch Or the resistor R22 is in contact, so that the thermistor NTC1 can be heated by the NPN transistor Q6 or the resistor R22; the thermistor NTC2 is in contact with the PNP transistor Q7 or the resistor R26 in the temperature control branch, so that the thermistor NTC2 can be PNP Transistor Q7 or resistor R26 is heated.

The thermistor NTC1 is connected in series with the resistor R13 and connected in parallel with the resistor R14. The two terminals are connected in parallel to the output terminal P1 of the current source I and the reference electrode of the voltage regulator. The thermistor NTC2 is connected in series with the resistor R17 and connected in parallel with the resistor R18. The two ends of the resistor are respectively connected to the reference pole of the voltage regulator and the anode of the voltage regulator; the input end of the resistor R12 is connected to the output end of the current source I, and the output end of the resistor R12 is connected to the input end of the device which generates the temperature drift in the power amplifier. The input end of the capacitor C3 is connected to the output end of the resistor R12, the output end of the capacitor C3 is connected to the negative terminal of the power supply -VCC and the anode of the voltage regulator, and the cathode of the voltage regulator is connected to the output end P1 of the current source I.

In this embodiment, the thermistor NTC1 and the thermistor NTC2 can also be replaced with the thermistor PTC1 and the thermistor PTC2 (not shown), thereby replacing the negative temperature coefficient thermistor (NTC) with the positive temperature coefficient. Thermistor (PTC), only need to contact the original contact scheme (thermistor NTC1 is in contact with the NPN transistor Q6 or resistor R22 in the temperature control branch, the thermistor NTC2 and the PNP transistor Q7 or resistor in the temperature control branch) R26 contact) is transferred (the thermistor PTC2 is in contact with the NPN transistor Q6 or the resistor R22 in the temperature control branch; the thermistor PTC1 is in contact with the PNP tertiary tube Q7 or the resistor R26 in the temperature control branch), other The circuit can refer to the connection method of the thermistor NTC1 and the thermistor NTC2.

Of course, the thermistor NTC1 and the thermistor NTC2 can also be replaced by other thermosensitive components (such as diodes, PN junctions of transistors, etc.), but in the present embodiment, the thermistor NTC1 and the thermistor NTC2 are mainly introduced. In addition, the voltage regulator can be used as a TL431 or a series regulator such as the LM317. However, in this embodiment, the voltage regulator TL431 is mainly taken as an example.

Overall working principle

Please continue to refer to FIG. 1. When the DC output potential of the output terminal OUT of the power amplifier in FIG. 1 is higher than the reference potential (ie, the potential of the input terminal GND of the resistor R19 in the reference potential branch is 0 volt), the operational amplifier branch The op amp OPAMP output terminal P2 of the circuit is high, the current enters the base of the NPN transistor Q6 through the resistor R21, the NPN transistor Q6 is turned on, and the NPN transistor Q6 and the resistor R22 generate heat. At this time, if the thermistor NTC1 is in contact with the NPN transistor Q6 or the resistor R22 in the temperature control branch (closely fitted), the thermistor NTC1 is heated and the resistance value is decreased, and the output voltage of the regulator TL431 is raised, resulting in an increase The bias voltage of the transistor Q4 is increased, and the current of the transistor Q4 is increased, the potential of the resistor R9 is pulled down, and the DC potential of the output terminal OUT of the power amplifier is dropped until it is equal to the reference potential.

When the DC output potential of the output terminal OUT of the power amplifier in FIG. 1 is lower than the reference potential (ie, 0 volt lower than the potential of the input terminal GND of the resistor R19 in the reference potential branch), the operational amplifier OPAMP output of the operational amplifier branch The terminal P2 is at a low potential, the current enters the base of the PNP transistor Q7 through the resistor R27, the PNP transistor Q7 is turned on, and the PNP transistor Q7 and the resistor R26 are heated. At this time, if the thermistor NTC2 is in contact with the PNP transistor Q7 or the resistor R26 in the temperature control branch (closely fitted), the heat is applied. When the resistance NTC2 is heated and the resistance is reduced, the output voltage of the regulator TL431 will decrease, causing the bias voltage of the transistor Q4 to decrease, and the current of the transistor Q4 is reduced, the potential of the resistor R9 is pulled high, and the output terminal OUT of the power amplifier is The DC potential rises until it is equal to the reference potential.

According to the same working principle, this embodiment can also use the active temperature control bias circuit at the base of the device such as the transistor Q1 or the transistor Q3 to achieve the same effect. In addition, although the embodiment mainly introduces the method of heating the voltage regulating circuit by the temperature control circuit as an example, the same effect can be achieved by using the temperature control circuit to cool the voltage regulating circuit.

The above-mentioned embodiments are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but is not to be construed as limiting the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the appended claims.

Claims

A DC output potential control device for a power amplifier, comprising: an active temperature control bias circuit, wherein the active temperature control bias circuit comprises a DC output potential deviation detecting circuit, a temperature control circuit, and a voltage regulating circuit The detection end of the DC output potential deviation detecting circuit is connected to the output end of the power amplifier; the output end of the DC output potential deviation detecting circuit is connected to the input end of the temperature control circuit; the output end of the voltage regulating circuit is The input end of the device for generating temperature drift in the power amplifier is connected; the DC output potential deviation detecting circuit detects a DC output potential deviation value of the power amplifier, and the temperature control circuit correspondingly according to the detected DC output potential deviation value The voltage regulating circuit is heated or cooled; the voltage regulating circuit adjusts a bias voltage of the device that generates temperature drift in the power amplifier according to heating or cooling of the temperature control circuit.
The apparatus for controlling a DC output potential of a power amplifier according to claim 1, wherein said DC output potential deviation detecting circuit comprises a low pass filter branch, a reference potential branch, and an operational amplifier branch; said low pass An input end of the filter branch is connected to an output end of the power amplifier; an output end of the low pass filter branch is connected to a positive input end of the operational amplifier branch; an input end of the reference potential branch is grounded, and an output thereof The terminal is connected to the negative input terminal of the operational amplifier branch; the output of the operational amplifier branch is connected to the input of the temperature control circuit.
The control device for DC output potential of a power amplifier according to claim 2, wherein said temperature control circuit comprises a reverse voltage protection branch and a temperature control branch connected to each other; said temperature control branch is detected according to The DC output potential deviation value is correspondingly heated or cooled by the voltage regulating circuit.
The control device for DC output potential of a power amplifier according to claim 2, wherein said temperature control circuit comprises an infrared heating branch; said infrared heating branch is correspondingly based on the detected DC output potential deviation value The voltage regulating circuit performs non-contact heating.
The control device for the DC output potential of the power amplifier according to claim 3, wherein the voltage regulating circuit comprises a heat-sensitive device branch and a voltage regulating branch connected to each other; and the temperature control branch is specifically The heat-sensitive device branch is heated or cooled according to the detected DC output potential deviation value; the output end of the voltage-regulating branch is connected to an input end of the device in the power amplifier that generates temperature drift.
The apparatus for controlling a DC output potential of a power amplifier according to claim 5, wherein in the DC output potential deviation detecting circuit, the low pass filter branch includes a resistor R23 and a capacitor C5; and the reference potential branch includes a resistor R19 The operational amplifier branch includes a resistor R20, a capacitor C4, a capacitor C5, and an operational amplifier OPAMP;

An input end of the low pass filter branch is connected to an output end of the power amplifier, an output end of the low pass filter branch is connected to a positive input end of the operational amplifier OPAMP; and the resistor R20 and the capacitor C4 are connected in parallel to be negative a feedback branch, an input end and an output end of the negative feedback branch are respectively connected to a negative input end and an output end of the operational amplifier OPAMP; wherein an input end of the resistor R19 is grounded in the reference potential branch, and an output end thereof is connected Input terminal of the negative feedback branch; the operation amplification The positive and negative power terminals of the OPAMP are connected to both ends of the DC power supply.
The control device for DC output potential of a power amplifier according to claim 6, wherein in the temperature control circuit, the reverse voltage protection branch includes a resistor R21, a resistor R27, a Zener diode D1, and a Zener diode D2. The temperature control branch includes a resistor R22, a resistor R26, an NPN transistor Q6, and a PNP tertiary tube Q7;

The input end of the resistor R21 is connected to the output end of the operational amplifier branch of the DC output potential deviation detecting circuit; the output end of the resistor R21 is connected to the base of the NPN transistor Q6 and the cathode of the Zener diode D1; the input end of the resistor R27 is connected to the DC output potential The output of the operational amplifier branch in the deviation detecting circuit; the output of the resistor R27 is connected to the base of the PNP tertiary tube Q7 and the anode of the Zener diode D2; the anode of the Zener diode D1 and the cathode of the Zener diode D2 are grounded; The input end of R22 is connected to the emitter of NPN transistor Q6, and its output terminal is grounded; the input end of resistor R26 is connected to the emitter of PNP three-stage tube Q7, and its output terminal is grounded; the collector of NPN transistor Q6 and the PNP three-stage tube Q7 The collector corresponds to both ends of the power supply.
The control device for DC output potential of a power amplifier according to claim 7, wherein in the voltage regulating circuit, the heat-sensitive device branch includes a thermistor NTC1, a thermistor NTC2, a resistor R13, and a resistor R14. a resistor R17 and a resistor R18; the voltage regulating branch includes a current source I, a voltage regulator, a resistor R12, and a capacitor C3; the thermistor NTC1 is in contact with an NPN transistor Q6 or a resistor R22 in the temperature control branch; the thermistor NTC2 is in contact with PNP tertiary tube Q7 or resistor R26 in the temperature control branch;

The thermistor NTC1 and the resistor R13 are connected in series and connected in parallel with the resistor R14. The two ends of the thermistor NTC1 are connected in parallel with the output terminal of the current source I and the reference electrode of the voltage regulator; the thermistor NTC2 is connected in series with the resistor R17 and the resistor R18 Parallel, parallel and connected to the reference pole of the voltage regulator and the anode of the voltage regulator respectively; the input end of the resistor R12 is connected to the output end of the current source I, and the output end of the resistor R12 is connected to the input of the device which generates the temperature drift in the power amplifier The input end of the capacitor C3 is connected to the output end of the resistor R12, the output end of the capacitor C3 is connected to the negative end of the power supply and the anode of the voltage regulator, and the cathode of the voltage regulator is connected to the output end of the current source I.
The control device for DC output potential of a power amplifier according to claim 7, wherein in the voltage regulating circuit, the heat-sensitive device branch includes a thermistor PTC1, a thermistor PTC2, a resistor R13, a resistor R14, a resistor R17 and a resistor R18; the voltage regulating branch includes a current source I, a voltage regulator, a resistor R12, and a capacitor C3; the thermistor PTC2 is in contact with an NPN transistor Q6 or a resistor R22 in the temperature control branch; the thermistor PTC1 is in contact with PNP tertiary tube Q7 or resistor R26 in the temperature control branch;

The thermistor PTC1 is connected in series with the resistor R13 in parallel with the resistor R14. The two ends of the thermistor PTC1 are connected in parallel with the output terminal of the current source I and the reference pole of the voltage regulator; the thermistor PTC2 is connected in series with the resistor R17 and the resistor R18 Parallel, parallel and connected to the reference pole of the regulator and the anode of the regulator respectively; the input of the resistor R12 is connected to the output of the current source I, The output end of the resistor R12 is connected to the input end of the device that generates the temperature drift in the power amplifier; the input end of the capacitor C3 is connected to the output end of the resistor R12, and the output end of the capacitor C3 is connected to the negative end of the power supply and the anode of the voltage regulator, the regulator The cathode is connected to the output of current source I.
The control device for DC output potential of a power amplifier according to claim 1, wherein the device for generating temperature drift in the power amplifier comprises any one of a diode, a triode, and a field effect transistor.