High-current power amplifier thick film circuit resistant to temperature of 200 DEG C and adjustable in gain

Abstract

The utility model belongs to the technical field of electronic circuits, and discloses a high-current power amplifier thick film circuit resistant to the temperature of 200 DEG C and adjustable in gain. The high-current power amplifier thick film circuit comprises an operational amplifier U1, the output end of the operational amplifier U1 is connected with an emitting electrode of an NPN triode Q5 and an emitting electrode of a PNP triode Q6; a pin 4 of the operational amplifier U1 is connected with a negative power supply VEE; a pin 7 of the operational amplifier U1 is connected with a positive power supply VCC; the PNP triode Q1 and the NPN triode Q3 form a Darlington tube; the NPN triode Q2 and the PNP triode Q4 form a Darlington tube; the NPN triode Q3 is connected with a positive power supply VCC through a resistor R5; the base electrode of the PNP triode Q4 and the base electrode of the PNP triode Q6 are connected with a negative power supply VEE through a resistor R6; the collector electrode of the NPN triode Q3 and the base electrode of the PNP triode Q1 are connected with a positive power supply VCC through a resistor R3; the collector electrode of the PNP triode Q4 and the base electrode of the NPN triode Q2 are connected with a negative power supply VEE through a resistor R4. The utility model adapts to characteristics and requirements of different signal sources; various gain amplification can be realized; the material has very good temperature stability in a high-temperature environment of 200 DEG C; and a bare chip thick film gold wire pressure welding process is adopted, so that the size of the module is reduced.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and more specifically, to a thick-film circuit for a high-current power amplifier with adjustable gain and a temperature resistance of 200°C. Background Technology

[0002] High-temperature, high-current power amplifiers are used to drive various sensors, actuators, and detection devices. These devices need to operate for extended periods in high-temperature and complex environments, requiring high-temperature resistant and stable power amplifiers.

[0003] The prior art publication CN105830342B provides a harmonic suppression circuit for a switch-mode power amplifier. A harmonic reduction bias generator drives a bias voltage across a cascaded control transistor connected in series with the drive transistor on the power amplifier, thereby suppressing even-order harmonics. A first bias voltage is generated by mirroring the pull-up current in the power amplifier. A p-channel source transistor and a p-channel cascaded current mirror transistor also mirror the pull-up current of the power amplifier to an intermediate node. An n-channel sink transistor and an n-channel cascaded current mirror transistor mirror the pull-down current in the power amplifier to the intermediate node. The operational amplifier compares the intermediate node with VDD / 2 and drives the gate of the p-channel feedback transistor. Current from the p-channel feedback transistor flows through the n-channel cascaded current mirror transistor, generating a second bias voltage. The second bias voltage is adjusted until the intermediate node reaches VDD / 2, resulting in better matching of the pull-up and pull-down currents in the power amplifier, thereby reducing even-order harmonics.

[0004] Although the existing technical solutions mentioned above can achieve the relevant beneficial effects through the existing technical structure, they still have the following drawbacks: traditional high-current power amplifiers are either not resistant to high temperatures or are large in size and have inflexible circuit adjustments.

[0005] In view of this, we propose a thick-film circuit for a high-current power amplifier with adjustable gain and a temperature resistance of 200℃. Utility Model Content

[0006] 1. Technical problems to be solved

[0007] The purpose of this application is to provide a high-current power amplifier thick-film circuit with adjustable gain and a temperature resistance of 200℃, solving the technical problems mentioned in the background art. It provides a high-temperature thick-film high-current power amplifier with small size, stable performance, and long-term high temperature resistance of 200℃, achieving complex functions with a limited number of components. This not only reduces the cost of the circuit but also improves its overall reliability. The circuit has extremely high flexibility; the signal can be input from either the positive or negative input terminal of the operational amplifier, adapting to the characteristics and requirements of different signal sources. By connecting external resistors of different values, various gain amplifications can be easily and quickly achieved, meeting the different signal amplification requirements of diverse application scenarios. The use of thick-film gold wire bonding technology ensures that the module maintains excellent temperature stability even at 200℃. The use of bare-chip thick-film gold wire bonding technology significantly reduces the size of the module.

[0008] 2. Technical Solution

[0009] This application provides a high-current power amplifier thick-film circuit with adjustable gain and a temperature resistance of 200℃, including: operational amplifier U1, PNP transistor Q1, NPN transistor Q3, NPN transistor Q5, PNP transistor Q6, NPN transistor Q2 and PNP transistor Q4.

[0010] The output terminal (pin 6) of operational amplifier U1 is connected to the emitter stage of NPN transistor Q5 and PNP transistor Q6; the processed signal is accurately output to the subsequent amplification stage.

[0011] Pin 4 of operational amplifier U1 is connected to the negative power supply VEE; pin 7 of operational amplifier U1 is connected to the positive power supply VCC; this provides stable power support for the normal operation of the operational amplifier, ensuring that its internal circuitry can accurately calculate and process the input signal under appropriate voltage conditions.

[0012] PNP transistor Q1 and NPN transistor Q3 form a Darlington transistor: the collector of NPN transistor Q3 is connected to the base of PNP transistor Q1, and the emitter of NPN transistor Q3 is connected to the collector of PNP transistor Q1 (pin OUT1); utilizing the high current gain characteristic of Darlington transistor, it can perform preliminary current amplification of the input signal.

[0013] NPN transistor Q2 and PNP transistor Q4 form a Darlington transistor. The collector of PNP transistor Q4 is connected to the base of NPN transistor Q2, and the emitter of PNP transistor Q4 is connected to the collector of NPN transistor Q2 (pin OUT2). This group of Darlington transistors works together with the previous group to further amplify the signal current and provide strong current support for driving the load.

[0014] The bases of NPN transistors Q3 and Q5 are connected to one end of resistor R5, and the other end of resistor R5 is connected to the positive power supply VCC; the bases of PNP transistors Q4 and Q6 are connected to one end of resistor R6, and the other end of resistor R6 is connected to the negative power supply VEE; these resistors act as biasing elements in the circuit, ensuring that the transistors are in the appropriate operating state and stably amplify the signal.

[0015] The collector of NPN transistor Q3 and the base of PNP transistor Q1 are connected to one end of resistor R3, and the other end of resistor R3 is connected to the positive power supply VCC; the collector of PNP transistor Q4 and the base of NPN transistor Q2 are connected to one end of resistor R4, and the other end of resistor R4 is connected to the negative power supply VEE; these two sets of resistors further optimize the operating characteristics of Darlington transistors and ensure the stability and accuracy of the signal amplification process.

[0016] The emitter of PNP transistor Q1 is connected to the positive power supply VCC; the emitter of NPN transistor Q2 is connected to the negative power supply VEE; thus providing the necessary power path for the Darlington transistor to operate.

[0017] At the output end, an external power resistor R1 is connected between pins OUT1 and OUT; an external power resistor R2 is connected between pins OUT2 and OUT. These two resistors mainly serve as current limiting protection, preventing excessive current from damaging the load and the circuit itself, and greatly improving the reliability and safety of the circuit.

[0018] As an optional solution of this utility model, an external resistor R8 is connected between the negative input terminal (pin 2) of operational amplifier U1 and ground (the gain of the entire circuit can be adjusted by changing the resistance value of resistor R8); by flexibly changing the resistance value of resistor R8, the gain of the entire circuit can be precisely adjusted. This design gives the circuit extremely high flexibility and can easily achieve different amplification factors of the input signal according to different application requirements.

[0019] As an optional solution of this utility model, an external matching resistor (R7 / / R8) is connected between the positive input terminal (pin 3) of the operational amplifier U1 and ground; the setting of this matching resistor can optimize the input characteristics of the circuit, ensure that the signal can be stably and accurately transmitted to the operational amplifier for processing at the input stage, and reduce signal distortion and interference.

[0020] Furthermore, to address the impact of high-temperature environments on circuit performance and prevent output signal distortion due to temperature changes, this circuit employs a unique compensation mechanism. Specifically:

[0021] The entire circuit uses the diode in NPN transistor Q5 (the same model as NPN transistor Q3) to perfectly compensate for the Darlington transistor composed of PNP transistor Q1 and NPN transistor Q3. When the temperature changes, the characteristics of the diode can automatically adjust the operating state of the Darlington transistor to counteract the negative impact of temperature on its performance.

[0022] The diodes in PNP transistor Q6 (the same model as PNP transistor Q4) perfectly compensate for the Darlington transistor composed of NPN transistor Q2 and PNP transistor Q4, preventing the output signal from becoming distorted with temperature changes. This ensures that the entire circuit can still output a stable and undistorted signal even at a high temperature of 200℃.

[0023] As an optional solution of this utility model, a major advantage of the thick-film circuit of the power amplifier is its powerful high-current driving capability.

[0024] By utilizing the Darlington transistors formed by PNP transistor Q1 and NPN transistor Q3, and the Darlington transistors formed by NPN transistor Q2 and PNP transistor Q4, a maximum peak current of 3A can be generated, enabling high-current drive of the load. This powerful current output capability allows the circuit to easily drive various high-power loads, making it widely applicable in industrial control, power electronics, and communication equipment.

[0025] As an optional solution of this utility model, the thick-film circuit of the high-current power amplifier with adjustable gain and a temperature resistance of 200℃ adopts a thick-film gold wire bonding process. In high-temperature environments, ordinary circuit connection methods are prone to many problems, while the thick-film gold wire bonding process can effectively address these issues. The thick-film conductor material used in thick-film technology has excellent high-temperature resistance characteristics. In a high-temperature environment of 200℃, the thick-film conductor can maintain stable electrical performance and will not undergo significant resistance changes due to high temperatures, thus ensuring the stability of signal transmission in the circuit. The thick-film conductor must possess excellent high-temperature resistance to ensure stable operation of the circuit in high-temperature environments. Common thick-film conductor materials include precious metal pastes and precious metal pastes;

[0026] Precious metal pastes: including silver-palladium alloy pastes and gold pastes, etc.;

[0027] Base metal pastes: including copper pastes and nickel pastes, etc.

[0028] These thick-film conductor materials, through their inherent characteristics, lay a solid foundation for the stable operation of high-current power amplifiers with adjustable gain up to 200℃ in high-temperature environments. They complement the thick-film gold wire bonding process, jointly ensuring the high performance of the circuit.

[0029] As an optional solution of this utility model, gold wire is used as the connecting medium, and a strong connection is achieved between the gold wire and the thick-film conductor through a special pressure welding process. This connection method can withstand the thermal stress caused by high temperatures and reduce poor contact caused by temperature changes. Compared with traditional welding methods, the connection points formed by thick-film gold wire pressure welding have higher mechanical strength and better electrical connection performance. In high-temperature environments, the connection points will not loosen or break, ensuring stable connections between components in the circuit and effectively avoiding signal interruptions or interference caused by unstable connections.

[0030] As an optional solution of this utility model, the thick-film gold wire bonding process involves precise control of process parameters during manufacturing. From the selection of gold wire and the bonding pressure to temperature, all parameters have undergone rigorous optimization. This enables the entire circuit module to maintain good temperature stability under high-temperature environments, and the drift of component parameters in the circuit is controlled within an extremely small range.

[0031] 3. Beneficial effects

[0032] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0033] 1. Component Streamlining: This circuit cleverly utilizes a limited number of components to achieve complex functions, resulting in a smaller component count. This not only reduces circuit costs but also minimizes the risk of failure due to an excessive number of components, thereby improving the overall reliability of the circuit.

[0034] 2. Excellent Flexibility: The circuit offers exceptional flexibility. Signals can be input from either the positive or negative input terminal of the operational amplifier, adapting to the characteristics and requirements of different signal sources. Furthermore, by connecting external resistors of varying values, amplification gains of various levels can be easily and quickly achieved, meeting the diverse signal amplification requirements of various application scenarios.

[0035] 3. Excellent High-Temperature Stability: The use of thick-film gold wire bonding technology is a major technological highlight of this circuit. This technology enables the module to maintain excellent temperature stability even at 200℃. In high-temperature environments, the thick-film gold wire bonding technology ensures the connection stability between components in the circuit, reduces problems such as poor contact and parameter drift caused by temperature changes, and ensures that the circuit performance is not affected by high temperatures, allowing for continuous and stable operation.

[0036] 4. Compact Size: Utilizing a bare-chip thick-film gold wire bonding process, the module's size is significantly reduced. In the trend of miniaturization and integration in modern electronic devices, this compact power amplifier thick-film circuit can be more easily integrated into various compact devices, providing strong support for miniaturized device design and enhancing the product's market competitiveness. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a high-current power amplifier thick-film circuit with adjustable gain and a temperature resistance of 200°C, as disclosed in a preferred embodiment of this application.

[0038] Figure 2 This is a schematic diagram of a high-current power amplifier thick-film circuit with adjustable gain and a temperature resistance of 200°C, disclosed in a preferred embodiment of this application, in which the input signal is connected to the positive input terminal and the gain is flexibly adjusted by resistor R8.

[0039] Figure 3 This is a schematic diagram of a high-current power amplifier thick-film circuit with adjustable gain and a temperature resistance of 200°C, disclosed in a preferred embodiment of this application. The input signal is connected to the negative input terminal, and the gain is flexibly adjusted by resistor R8. Detailed Implementation

[0040] The present application will be further described in detail below with reference to the accompanying drawings.

[0041] Reference Figure 1 , Figure 2 and Figure 3 This application provides a high-current power amplifier thick-film circuit with adjustable gain and a temperature resistance of 200℃, including: operational amplifier U1, PNP transistor Q1, NPN transistor Q3, NPN transistor Q5, PNP transistor Q6, NPN transistor Q2 and PNP transistor Q4.

[0042] Operational amplifier U1 plays a central role in the entire circuit.

[0043] The output terminal (pin 6) of operational amplifier U1 is connected to the emitter stage of NPN transistor Q5 and PNP transistor Q6; acting as a hub for circuit signal transmission, it accurately outputs the processed signal to the subsequent amplification stage.

[0044] Pin 4 of operational amplifier U1 is connected to the negative power supply VEE; pin 7 of operational amplifier U1 is connected to the positive power supply VCC; this provides stable power support for the normal operation of the operational amplifier, ensuring that its internal circuitry can accurately calculate and process the input signal under appropriate voltage conditions.

[0045] PNP transistor Q1 and NPN transistor Q3 form a Darlington transistor: the collector of NPN transistor Q3 is connected to the base of PNP transistor Q1, and the emitter of NPN transistor Q3 is connected to the collector of PNP transistor Q1 (pin OUT1). This connection method cleverly utilizes the high current gain characteristic of Darlington transistors, which can perform preliminary current amplification of the input signal.

[0046] NPN transistor Q2 and PNP transistor Q4 are both Darlington transistors. The collector of PNP transistor Q4 is connected to the base of NPN transistor Q2, and the emitter of PNP transistor Q4 is connected to the collector of NPN transistor Q2 (pin OUT2). This group of Darlington transistors works together with the previous group to further amplify the signal current and provide strong current support for driving the load.

[0047] The bases of NPN transistors Q3 and Q5 are connected to one end of resistor R5, and the other end of resistor R5 is connected to the positive power supply VCC; the bases of PNP transistors Q4 and Q6 are connected to one end of resistor R6, and the other end of resistor R6 is connected to the negative power supply VEE; these resistors act as biasing elements in the circuit, ensuring that the transistors are in the appropriate operating state and stably amplify the signal.

[0048] The collector of NPN transistor Q3 and the base of PNP transistor Q1 are connected to one end of resistor R3, and the other end of resistor R3 is connected to the positive power supply VCC; the collector of PNP transistor Q4 and the base of NPN transistor Q2 are connected to one end of resistor R4, and the other end of resistor R4 is connected to the negative power supply VEE; these two sets of resistors further optimize the operating characteristics of Darlington transistors and ensure the stability and accuracy of the signal amplification process.

[0049] The emitter of PNP transistor Q1 is connected to the positive power supply VCC; the emitter of NPN transistor Q2 is connected to the negative power supply VEE; thus providing the necessary power path for the Darlington transistor to operate.

[0050] At the output terminal, an external power resistor R1 is connected between pins OUT1 and OUT (to provide current limiting protection); an external power resistor R2 is connected between pins OUT2 and OUT (to provide current limiting protection). These two resistors mainly serve the purpose of current limiting protection, preventing excessive current from damaging the load and the circuit itself, and greatly improving the reliability and safety of the circuit.

[0051] Reference Figure 2 and Figure 3An external resistor R8 is connected between the negative input terminal (pin 2) of operational amplifier U1 and ground (the gain of the entire circuit is adjusted by changing the value of resistor R8); by flexibly changing the value of resistor R8, the gain of the entire circuit can be precisely adjusted. This design gives the circuit extremely high flexibility, and can easily achieve different amplification factors of the input signal according to different application requirements.

[0052] Furthermore, an external matching resistor (R7 / / R8) is connected between the positive input terminal (pin 3) of operational amplifier U1 and ground; the setting of this matching resistor can optimize the input characteristics of the circuit, ensure that the signal can be stably and accurately transmitted to the operational amplifier for processing at the input stage, and reduce signal distortion and interference.

[0053] Furthermore, to address the impact of high-temperature environments on circuit performance and prevent output signal distortion due to temperature changes, this circuit employs a unique compensation mechanism. Specifically,

[0054] The entire circuit uses the diode in NPN transistor Q5 (the same model as NPN transistor Q3) to perfectly compensate for the Darlington transistor composed of PNP transistor Q1 and NPN transistor Q3. When the temperature changes, the characteristics of the diode can automatically adjust the operating state of the Darlington transistor to counteract the negative impact of temperature on its performance.

[0055] Similarly, the diodes in PNP transistor Q6 (the same model as PNP transistor Q4) perfectly compensate for the Darlington transistor composed of NPN transistor Q2 and PNP transistor Q4, without producing a distorted output signal with temperature changes; thus ensuring that the entire circuit can still output a stable and undistorted signal in a high-temperature environment of 200℃.

[0056] Furthermore, a major advantage of this power amplifier thick-film circuit is its powerful high-current drive capability.

[0057] By utilizing the Darlington transistors formed by PNP transistor Q1 and NPN transistor Q3, and the Darlington transistors formed by NPN transistor Q2 and PNP transistor Q4, a maximum peak current of 3A can be generated, enabling high-current drive of the load. This powerful current output capability allows the circuit to easily drive various high-power loads, making it widely applicable in industrial control, power electronics, and communication equipment.

[0058] Furthermore, the thick-film circuit of this high-current power amplifier with adjustable gain and a temperature resistance of 200℃ adopts a thick-film gold wire bonding process. In high-temperature environments, ordinary circuit connection methods are prone to many problems, while the thick-film gold wire bonding process can effectively address these issues. The thick-film conductor material used in thick-film technology has excellent high-temperature resistance characteristics. In a high-temperature environment of 200℃, the thick-film conductor can maintain stable electrical performance and will not experience significant resistance changes due to high temperatures, thus ensuring the stability of signal transmission in the circuit. The thick-film conductor must possess excellent high-temperature resistance to ensure stable circuit operation in high-temperature environments. Common thick-film conductor materials include precious metal pastes and precious metal pastes;

[0059] Precious metal pastes: including silver-palladium alloy pastes and gold pastes, etc.;

[0060] Silver-palladium alloy paste: Silver (Ag) possesses excellent electrical conductivity, ranking among the highest of common metals, effectively reducing resistance loss during signal transmission. Palladium (Pd) enhances the material's chemical stability and high-temperature resistance. At 200℃, the silver-palladium alloy paste maintains structural stability and does not easily react chemically with the surrounding environment, preventing increased resistance or decreased connection performance due to oxidation, thus ensuring the stability of circuit signal transmission.

[0061] Gold paste: Gold (Au) is chemically extremely stable, hardly reacting with other substances, and maintains excellent electrical properties even in harsh environments such as high temperature and high humidity. Gold also has high electrical conductivity, providing a low-resistance signal transmission path for circuits. Using gold paste as a conductor in thick-film circuits can significantly improve circuit reliability and lifespan, making it particularly suitable for electronic devices with extremely high stability requirements.

[0062] Base metal pastes: including copper pastes and nickel pastes, etc.;

[0063] Copper paste: Copper (Cu) has high electrical conductivity and relatively low cost, making it a cost-effective choice for thick-film conductors. To ensure stable operation at 200°C, it is often treated with special processes, such as adding an anti-oxidation coating to the surface to prevent oxidation and maintain conductivity at high temperatures. After treatment, the copper paste can provide a stable signal transmission channel for circuits while meeting certain cost requirements.

[0064] Nickel paste: Nickel (Ni) possesses excellent high-temperature resistance and corrosion resistance, and is not easily deformed or damaged in high-temperature environments. Although its electrical conductivity is slightly lower than that of metals such as silver and copper, nickel paste can be used as a thick-film conductor material in some cost-sensitive applications where conductivity requirements are not extremely high. It can maintain the stability of its structure and electrical properties at high temperatures up to 200°C, ensuring the reliability of connections between components in the circuit.

[0065] These thick-film conductor materials, through their inherent characteristics, lay a solid foundation for the stable operation of high-current power amplifiers with adjustable gain up to 200℃ in high-temperature environments. They complement the thick-film gold wire bonding process, jointly ensuring the high performance of the circuit.

[0066] Furthermore, gold wire is used as the connecting medium, and a strong connection is achieved between the gold wire and the thick-film conductor through a special pressure welding process. This connection method can withstand the thermal stress caused by high temperatures and reduce poor contact caused by temperature changes. Compared with traditional welding methods, the connection points formed by thick-film gold wire pressure welding have higher mechanical strength and better electrical connection performance. In high-temperature environments, the connection points will not loosen or break, ensuring stable connections between components in the circuit and effectively avoiding signal interruptions or interference caused by unstable connections.

[0067] Furthermore, the thick-film gold wire bonding process involves precise control of process parameters during manufacturing. From the selection of gold wire and the bonding pressure to the temperature, all parameters have undergone rigorous optimization. This ensures that the entire circuit module maintains excellent temperature stability under high-temperature environments, and the drift of component parameters is controlled within a very small range. For example, the parameters of components such as resistors and capacitors may change under high temperatures, but the thick-film gold wire bonding process can minimize this parameter drift through stable connections and effective resistance to environmental factors, thereby ensuring that circuit performance is unaffected by high temperatures and operates continuously and stably.

[0068] This invention employs a bare-chip thick-film gold wire bonding process, significantly reducing the module's size. This advantage is particularly important in the current trend of miniaturization and integration in modern electronic devices. Traditional circuit packaging methods typically require considerable space to accommodate chips, pins, and other connecting components. The bare-chip thick-film gold wire bonding process directly connects the chip to the thick-film circuit, eliminating much of the redundancy found in traditional packaging. The bare chip itself is small, and by directly integrating it into the thick-film circuit through the gold wire bonding process, the additional space occupied by traditional packaging is avoided. The fine diameter of the gold wire and the precision of the bonding process allow for a rational layout of the connecting lines within a limited space, further reducing the overall module size. This compact power amplifier thick-film circuit can be more easily integrated into various compact devices.

[0069] The beneficial effects achieved by this utility model are: fewer components are used; it has high flexibility, allowing signals to be input from either the positive or negative input terminals of the operational amplifier; and it can also achieve amplification of various gains through external resistors. The use of thick-film gold wire bonding technology ensures that the module maintains excellent temperature stability even at 200℃. The use of bare-chip thick-film gold wire bonding technology significantly reduces the module size.

[0070] The above-described embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A thick-film circuit for a high-current power amplifier with adjustable gain and a temperature resistance of 200℃, comprising: Operational amplifier U1, PNP transistor Q1, NPN transistor Q3, NPN transistor Q5, PNP transistor Q6, NPN transistor Q2, and PNP transistor Q4; characterized in that: The output of operational amplifier U1 is connected to the emitter stage of NPN transistor Q5 and PNP transistor Q6; Pin 4 of operational amplifier U1 is connected to the negative power supply VEE; pin 7 of operational amplifier U1 is connected to the positive power supply VCC. PNP transistor Q1 and NPN transistor Q3 form a Darlington transistor: the collector of NPN transistor Q3 is connected to the base of PNP transistor Q1, and the emitter of NPN transistor Q3 is connected to the collector of PNP transistor Q1. NPN transistor Q2 and PNP transistor Q4 form a Darlington transistor: the collector of PNP transistor Q4 is connected to the base of NPN transistor Q2, and the emitter of PNP transistor Q4 is connected to the collector of NPN transistor Q2. The base of NPN transistor Q3 and the base of NPN transistor Q5 are connected to one end of resistor R5, and the other end of resistor R5 is connected to the positive power supply VCC; the base of PNP transistor Q4 and the base of PNP transistor Q6 are connected to one end of resistor R6, and the other end of resistor R6 is connected to the negative power supply VEE. The collector of NPN transistor Q3 and the base of PNP transistor Q1 are connected to one end of resistor R3, and the other end of resistor R3 is connected to the positive power supply VCC; the collector of PNP transistor Q4 and the base of NPN transistor Q2 are connected to one end of resistor R4, and the other end of resistor R4 is connected to the negative power supply VEE. The emitter of PNP transistor Q1 is connected to the positive power supply VCC; the emitter of NPN transistor Q2 is connected to the negative power supply VEE.

2. The thick-film circuit of the high-current power amplifier with adjustable gain and a temperature resistance of 200℃ as described in claim 1, characterized in that: At the output terminal, an external power resistor R1 is connected between pins OUT1 and OUT; an external power resistor R2 is connected between pins OUT2 and OUT; this serves as a current limiting protection.

3. The thick-film circuit of the high-current power amplifier with adjustable gain and a temperature resistance of 200℃ as described in claim 1, characterized in that: An external resistor R8 is connected between the negative input terminal 2 of the operational amplifier U1 and ground. The gain of the entire circuit can be adjusted by changing the resistance value of resistor R8.

4. The thick-film circuit of the high-current power amplifier with adjustable gain and a temperature resistance of 200℃ as described in claim 1, characterized in that: An external matching resistor R7 / / R8 is connected between the positive input terminal 3 of the operational amplifier U1 and ground; the setting of this matching resistor can optimize the input characteristics of the circuit and reduce signal distortion and interference.

5. The thick-film circuit of a high-current power amplifier with adjustable gain and a temperature resistance of 200℃ as described in claim 1, characterized in that: The circuit employs a compensation mechanism, specifically: The entire circuit uses the diode in NPN transistor Q5 to perfectly compensate for the Darlington transistor composed of PNP transistor Q1 and NPN transistor Q3. When the temperature changes, the characteristics of the diode can automatically adjust the working state of the Darlington transistor to counteract the negative impact of temperature on its performance. The diodes in PNP transistor Q6 perfectly compensate for the Darlington transistor composed of NPN transistor Q2 and PNP transistor Q4, preventing the output signal from becoming distorted with temperature changes. This ensures that the entire circuit can still output a stable and undistorted signal even at a high temperature of 200℃.

6. The thick-film circuit of a high-current power amplifier with adjustable gain and a temperature resistance of 200℃ as described in claim 1, characterized in that: The circuit uses a thick-film gold wire bonding process. The thick-film conductor must have high temperature resistance to ensure stable operation of the circuit in high-temperature environments.

7. The thick-film circuit of a high-current power amplifier with adjustable gain and a temperature resistance of 200℃ as described in claim 6, characterized in that: Thick-film conductor materials are precious metal pastes, including silver-palladium alloy pastes and gold pastes.

8. The thick-film circuit of a high-current power amplifier with adjustable gain and a temperature resistance of 200℃ according to claim 6, characterized in that: Thick-film conductor materials are base metal pastes, including copper pastes and nickel pastes.

9. The thick-film circuit of a high-current power amplifier with adjustable gain and a temperature resistance of 200℃ as described in claim 6, characterized in that: Gold wire is used as the connecting medium, and a strong connection is achieved between the gold wire and the thick film conductor through a pressure welding process.

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