Low-temperature-drift secondary amplification circuit

Abstract

The invention discloses a low-temperature-drift two-stage amplification circuit which comprises a first-stage amplification circuit module, a second-stage amplification circuit module and a summing circuit module. The output end of the primary amplification circuit module is electrically connected with the input end of the secondary amplification circuit module, and the output end of the secondary amplification circuit module is electrically connected with the input end of the summing circuit module; the primary amplification circuit module is used for primarily amplifying an input signal, outputting a first signal and transmitting the first signal to the secondary amplification circuit module; the secondary amplification circuit module further amplifies the received first signal, outputs a second signal and transmits the second signal to the summing circuit module; and the summing circuit module adds a reference voltage to the received second signal, modulates a final output zero voltage and outputs a final output signal. Therefore, perfect combination of high magnification and low temperature drift is realized.

Description

Technical Field

[0001] The invention relates to the technical field of airborne aviation products, and in particular to a low-temperature drift secondary amplifier circuit. Background Art

[0002] In airborne aviation products, sensor signals usually need to be amplified to meet the needs of subsequent circuits. Since sensor signals often have the characteristics of low amplitude and high safety overload, the amplifier circuit is required to have an amplification capacity of up to 1500~2000 times. However, at such a high amplification factor, the traditional amplifier circuit is prone to excessive temperature drift of the output signal due to the input / output offset voltage temperature drift characteristics of the operational amplifier chip, which cannot meet the use requirements. Therefore, it is particularly important to develop an amplifier circuit that can achieve high-multiple amplification and effectively control temperature drift. Summary of the invention

[0003] The present application provides a low temperature drift two-stage amplifier circuit and proposes a two-stage amplifier circuit design based on a combination of a domestic instrument operational amplifier and a common precision operational amplifier, thereby achieving a perfect combination of high amplification factor and low temperature drift.

[0004] The present application provides a low-temperature drift two-stage amplifier circuit, comprising a first-stage amplifier circuit module, a second-stage amplifier circuit module, and an addition circuit module; the output end of the first-stage amplifier circuit module is electrically connected to the input end of the second-stage amplifier circuit module, and the output end of the second-stage amplifier circuit module is electrically connected to the input end of the addition circuit module; The first-stage amplifying circuit module preliminarily amplifies the input signal and outputs a first signal which is transmitted to the second-stage amplifying circuit module; The secondary amplification circuit module further amplifies the received first signal and outputs a second signal to be transmitted to the addition circuit module; The adding circuit module adds a reference voltage to the received second signal, modulates the zero-position voltage outputted finally, and outputs a final output signal.

[0005] Preferably, the first-stage amplification circuit module includes: a first instrumentation operational amplifier, a first transient voltage suppression diode, a second transient voltage suppression diode, a second potentiometer, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a sixth capacitor, a seventh capacitor, a ninth capacitor, a first resistor, a fourth resistor, a tenth resistor, a thirteenth resistor, a fourteenth resistor, and a fifteenth resistor; The secondary amplification circuit module includes: a first common precision operational amplifier, a first potentiometer, a fifth capacitor, an eighth capacitor, a fifth resistor, an eleventh resistor, and a twelfth resistor; The adding circuit module includes: a second ordinary precision operational amplifier, a second resistor, a third resistor, a sixth resistor, a seventh resistor, and an eighth resistor.

[0006] Preferably, pin 1 of the first instrument operational amplifier is connected to pin 8 through a fifteenth resistor to form a feedback loop; pin 2 of the first instrument operational amplifier is respectively connected to the tenth resistor, one end of the sixth capacitor and one end of the seventh capacitor, and the other end of the tenth resistor is connected to the negative end S1- of the input signal; pin 3 of the first instrument operational amplifier is respectively connected to the thirteenth resistor, one end of the ninth capacitor and the other end of the seventh capacitor, and the other end of the thirteenth resistor is connected to the positive end S1+ of the input signal; pin 4 of the first instrument operational amplifier is connected to one end of the first capacitor and the fourth capacitor through a first resistor, and the other end of the first resistor is connected to the input -12V DC power supply; pin 5 of the first instrument operational amplifier is directly connected to the power ground GND; pin 6 of the first instrument operational amplifier is connected to one end of the twelfth resistor, and the other end of the twelfth resistor is connected to the input end of the secondary amplifier circuit module; pin 7 of the first instrument operational amplifier is connected to one end of the second capacitor and the third capacitor through a fourth resistor, the other ends of the second capacitor and the third capacitor are connected to the power ground GND, and the other end of the fourth resistor is connected to the input +12V DC power supply; pin 8 of the first instrument operational amplifier is connected to pin 1 through a fifteenth resistor.

[0007] Preferably, one end of the first transient voltage suppression diode is connected to the input signal negative terminal S1-, and the other end is connected to the power ground GND, so as to protect the circuit from the influence of negative transient voltage; One end of the second transient voltage suppression diode is connected to the input signal positive terminal S1+, and the other end is connected to the power ground GND, which is used to protect the circuit from the influence of forward transient voltage; The pin 1 of the second potentiometer is connected to the negative terminal S1- of the input signal, the pin 2 is connected to the positive terminal S1+ of the input signal, and the pin 3 is connected to the power ground GND through the fourteenth resistor, which is used to adjust the attenuation or gain of the input signal; The first capacitor, the second capacitor, the third capacitor and the fourth capacitor are respectively used as filter capacitors, and the other ends of the capacitors are connected to the power ground GND to filter out high-frequency noise in the power supply or signal; The sixth capacitor and the ninth capacitor are used as decoupling capacitors, respectively connected between the 2nd and 3rd pins of the first instrument operational amplifier and the power ground GND to reduce the influence of power supply fluctuations on the amplifier performance; The seventh capacitor is connected across the 2nd and 3rd pins of the first instrument operational amplifier, serving as a coupling capacitor of the differential input terminal; The first resistor and the fourth resistor are used as current limiting resistors, and are respectively connected between the first capacitor, the fourth capacitor, the second capacitor, the third capacitor and the corresponding DC power supply; The tenth resistor and the thirteenth resistor are used as output resistors and are respectively connected between the 2nd and 3rd pins of the first instrument operational amplifier and the input signal terminals S1- and S1+; The fourteenth resistor cooperates with the second potentiometer to adjust the bias of the input signal; The fifteenth resistor is used as a feedback resistor and is connected between pins 1 and 8 of the first instrumentation operational amplifier to set the gain of the amplifier.

[0008] Preferably, pin 1 of the first ordinary precision operational amplifier is connected to pin 5 of the second ordinary precision operational amplifier through a sixth resistor to form feedback of the common-phase input terminal; pin 2 of the first ordinary precision operational amplifier is respectively connected to one end of the eleventh resistor and the fifth resistor, the other end of the eleventh resistor is connected to the power ground GND, and the other end of the fifth resistor is connected to pin 1 of the first potentiometer; pin 3 of the first ordinary precision operational amplifier is connected to one end of the twelfth resistor, and the other end of the twelfth resistor is connected to pin 6 of the first instrumentation operational amplifier; pin 4 of the first ordinary precision operational amplifier is connected to the input -12V DC power supply; pin 8 of the first ordinary precision operational amplifier is connected to the input +12V DC power supply.

[0009] Preferably, pin 1 of the first potentiometer is connected to a fifth resistor, and pins 2 and 3 of the first potentiometer are connected in parallel to pin 1 of a first common precision operational amplifier, for adjusting the gain or bias of the amplifier; The fifth capacitor and the eighth capacitor are used as filter capacitors of the positive and negative power supplies respectively, and the other ends thereof are connected to the power ground GND; The fifth resistor and the eleventh resistor serve as bias and current limiting resistors at the input end; The twelfth resistor is used as a signal transmission resistor connecting the primary amplifying circuit module and the secondary amplifying circuit module.

[0010] Preferably, pin 6 of the second ordinary precision operational amplifier is connected to the power ground GND through a second resistor to form a bias for the inverting input terminal; pin 7 of the second ordinary precision operational amplifier is connected to the node between pin 6 and pin 7 of the second ordinary precision operational amplifier through a third resistor to realize signal addition operation; pin 5 of the second ordinary precision operational amplifier is connected to one end of the eighth resistor, and the other end of the eighth resistor is connected to the input reference voltage; pin 5 of the second ordinary precision operational amplifier is also connected to pin 1 of the first ordinary precision operational amplifier through a sixth resistor to form feedback for the in-phase input terminal; pin 7 of the second ordinary precision operational amplifier is used as the output terminal, directly connected to one end of the seventh resistor, and the other end of the seventh resistor is used to output the final output signal.

[0011] Preferably, the second resistor and the third resistor constitute a bias and feedback network of the inverting input terminal; the sixth resistor serves as a feedback resistor of the non-inverting input terminal; the seventh resistor serves as an output resistor; and the eighth resistor is used to limit the input of the reference voltage.

[0012] Preferably, the first-stage amplification circuit module is specifically used for: The input signal is protected by a first transient voltage suppression diode and a second transient voltage suppression diode and then connected to the input end of the first instrument operational amplifier; The first capacitor, the second capacitor, the third capacitor, the fourth capacitor, the first resistor and the fourth resistor form a power filter network to ensure power stability; The sixth capacitor, the seventh capacitor, the ninth capacitor cooperate with the tenth resistor, the thirteenth resistor, and the fifteenth resistor to achieve signal filtering and amplification; The second potentiometer is used to adjust the zero position of the input signal.

[0013] Preferably, the secondary amplifier circuit module is specifically used for: Connecting the received first signal to the input end of the first common precision operational amplifier through the twelfth resistor; The fifth capacitor, the eighth capacitor, the fifth resistor and the eleventh resistor form a power supply filter network; The first potentiometer is used to adjust the amplification factor; The adding circuit module is specifically used for: Input the received second signal and the set reference voltage into the second common precision operational amplifier through the sixth resistor and the eighth resistor; The second resistor, the third resistor and the seventh resistor form a feedback network to achieve accurate adjustment of the signal; The final output signal is led out through the seventh resistor.

[0014] One or more technical solutions provided in this application have at least the following technical effects or advantages: Through the two-stage amplification design, when the sensor signal is input, RC filtering is first performed, and the first instrument operational amplifier U2 first amplifies it by about 412 times, and then the first ordinary precision operational amplifier U1A amplifies it by 4~5 times, and the two stages amplify it by 1648~2060 times in total; at the same time, the second ordinary precision operational amplifier U1B adds a reference voltage to modulate the final output zero-position voltage. Thus, a high amplification factor of 1500~2000 times is achieved, meeting the signal amplification requirements of airborne sensors; domestic high-performance components are selected, and through careful circuit design, the influence of temperature on the amplification factor and output signal is effectively reduced, ensuring that the circuit works stably within a wide temperature range; through the reference voltage design in the second potentiometer W2 and the addition circuit module 30, the zero-position adjustable function of the output signal is realized, which improves the flexibility and adaptability of the circuit; the addition of transient voltage suppression diodes effectively protects the circuit from damage by transient overvoltage and improves the reliability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of a low temperature drift two-stage amplifier circuit according to an embodiment of the present invention; Figure 2A circuit diagram of a low temperature drift secondary amplifier circuit according to an embodiment of the present invention; In the figure: 100-low temperature drift secondary amplifier circuit; 10-primary amplifier circuit module; 20-secondary amplifier circuit module; 30-addition circuit module; U2-first instrument operational amplifier; U1A-first ordinary precision operational amplifier; U1B-second ordinary precision operational amplifier; D1-first transient voltage suppression diode; D2-second transient voltage suppression diode; W1-first potentiometer; W2-second potentiometer; C1-first capacitor; C2-second capacitor; C3-third capacitor; C 4-the fourth capacitor; C5-the fifth capacitor; C6-the sixth capacitor; C7-the seventh capacitor; C8-the eighth capacitor; C9-the ninth capacitor; R1-the first resistor; R2-the second resistor; R3-the third resistor; R4-the fourth resistor; R5-the fifth resistor; R6-the sixth resistor; R7-the seventh resistor; R8-the eighth resistor; R10-the tenth resistor; R11-the eleventh resistor; R12-the twelfth resistor; R13-the thirteenth resistor; R14-the fourteenth resistor; R15-the fifteenth resistor. DETAILED DESCRIPTION

[0016] In order to facilitate the understanding of the present invention, the present application will be described more comprehensively below with reference to the relevant drawings.

[0017] Figure 1 It is a structural schematic diagram of a low temperature drift two-stage amplifier circuit according to an embodiment of the present invention.

[0018] like Figure 1 As shown, the low temperature drift two-stage amplifier circuit 100 includes: a first-stage amplifier circuit module 10 , a second-stage amplifier circuit module 20 , and an adding circuit module 30 .

[0019] Specifically, the output end of the first-stage amplifying circuit module 10 is electrically connected to the input end of the second-stage amplifying circuit module 20 ; the output end of the second-stage amplifying circuit module 20 is electrically connected to the input end of the adding circuit module 30 .

[0020] Figure 2 Schematic diagram of a low temperature drift two-stage amplifier circuit according to an embodiment of the present invention.

[0021] like Figure 2 As shown, the low temperature drift two-stage amplifier circuit 100 includes a first-stage amplifier circuit module 10 , a second-stage amplifier circuit module 20 , and an adding circuit module 30 .

[0022] In some embodiments, the first-stage amplifier circuit module 10 includes: a first instrumentation operational amplifier U2, a first transient voltage suppression diode D1, a second transient voltage suppression diode D2, a second potentiometer W2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a sixth capacitor C6, a seventh capacitor C7, a ninth capacitor C9, a first resistor R1, a fourth resistor R4, a tenth resistor R10, a thirteenth resistor R13, a fourteenth resistor R14, and a fifteenth resistor R15; Specifically, the first-stage amplifier circuit module 10 realizes preliminary amplification of the input signal, with an amplification factor of about 412 times, and outputs a first signal; the input signal is protected by the first transient voltage suppression diode D1 and the second transient voltage suppression diode D2, and then connected to the input end of the first instrument operational amplifier U2; the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4 and the first resistor R1 and the fourth resistor R4 form a power supply filtering network to ensure power supply stability; the sixth capacitor C6, the seventh capacitor C7, the ninth capacitor C9 cooperate with the tenth resistor R10, the thirteenth resistor R13, and the fifteenth resistor R15 to realize signal filtering and amplification; the second potentiometer W2 is used to adjust the zero position of the input signal; Among them, the pin 1 of the first instrument operational amplifier U2 is connected to the pin 8 through the fifteenth resistor R15 to form a feedback loop; the pin 2 of the first instrument operational amplifier U2 is respectively connected to the tenth resistor R10, one end of the sixth capacitor C6 and one end of the seventh capacitor C7, and the other end of the tenth resistor R10 is connected to the input signal negative terminal S1-; the pin 3 of the first instrument operational amplifier U2 is respectively connected to the thirteenth resistor R13, one end of the ninth capacitor C9 and the other end of the seventh capacitor C7, and the other end of the thirteenth resistor R13 is connected to the input signal positive terminal S1+; the pin 4 of the first instrument operational amplifier U2 is connected to the first capacitor C1 and one end of the fourth capacitor C4 through the first resistor R1, and The other end of the first resistor R1 is connected to the input -12V DC power supply; the 5th pin of the first instrument operational amplifier U2 is directly connected to the power ground GND; the 6th pin of the first instrument operational amplifier U2 is connected to one end of the twelfth resistor R12, and the other end of the twelfth resistor R12 is connected to the input end of the secondary amplifier circuit module 20; the 7th pin of the first instrument operational amplifier U2 is connected to one end of the second capacitor C2 and the third capacitor C3 through the fourth resistor R4, the other ends of the second capacitor C2 and the third capacitor C3 are connected to the power ground GND, and the other end of the fourth resistor R4 is connected to the input +12V DC power supply; the 8th pin of the first instrument operational amplifier U2 is connected to the 1st pin through the fifteenth resistor R15; One end of the first transient voltage suppression diode D1 is connected to the input signal negative terminal S1-, and the other end is connected to the power ground GND, so as to protect the circuit from the influence of negative transient voltage; One end of the second transient voltage suppression diode D2 is connected to the input signal positive terminal S1+, and the other end is connected to the power ground GND, so as to protect the circuit from the influence of the forward transient voltage; The pin 1 of the second potentiometer W2 is connected to the negative terminal S1- of the input signal, the pin 2 is connected to the positive terminal S1+ of the input signal, and the pin 3 is connected to the power ground GND through the fourteenth resistor R14, for adjusting the attenuation or gain of the input signal; The first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 are respectively used as filter capacitors, and the other ends of the capacitors are connected to the power ground GND to filter out high-frequency noise in the power supply or signal; The sixth capacitor C6 and the ninth capacitor C9 are used as decoupling capacitors, and are respectively connected between the 2nd and 3rd pins of the first instrument operational amplifier U2 and the power ground GND to reduce the influence of power supply fluctuations on the amplifier performance; The seventh capacitor C7 is connected across the pins 2 and 3 of the first instrument operational amplifier U2, and serves as a coupling capacitor of the differential input terminal; The first resistor R1 and the fourth resistor R4 are used as current limiting resistors, and are respectively connected between the first capacitor C1, the fourth capacitor C4, the second capacitor C2, the third capacitor C3 and the corresponding DC power supply; The tenth resistor R10 and the thirteenth resistor R13 are used as output resistors and are respectively connected between the 2nd and 3rd pins of the first instrument operational amplifier U2 and the input signal terminals S1- and S1+; The fourteenth resistor R14 cooperates with the second potentiometer W2 to adjust the bias of the input signal; The fifteenth resistor R15 is used as a feedback resistor and is connected between pins 1 and 8 of the first instrumentation operational amplifier U2 to set the gain of the amplifier.

[0023] In some embodiments, the output end of the primary amplifier circuit module 10 is connected to the input end of the secondary amplifier circuit module 20 through the twelfth resistor R12, and the secondary amplifier circuit module 20 includes: a first common precision operational amplifier U1A, a first potentiometer W1, a fifth capacitor C5, an eighth capacitor C8, a fifth resistor R5, an eleventh resistor R11, and a twelfth resistor R12; Specifically, the secondary amplifier circuit module 20 further amplifies the first signal amplified by the primary amplifier circuit module 10, with an amplification factor of about 4-5 times, and outputs a second signal; the output signal of the primary amplifier circuit module 10 is connected to the input end of the first ordinary precision operational amplifier U1A through the twelfth resistor R12; the fifth capacitor C5, the eighth capacitor C8, the fifth resistor R5, and the eleventh resistor R11 form a power supply filter network; the first potentiometer W1 is used to adjust the amplification factor; Among them, pin 1 of the first ordinary precision operational amplifier U1A is connected to pin 5 of the second ordinary precision operational amplifier U1B through the sixth resistor R6, forming feedback of the in-phase input terminal; pin 2 of the first ordinary precision operational amplifier U1A is respectively connected to one end of the eleventh resistor R11 and the fifth resistor R5, the other end of the eleventh resistor R11 is connected to the power ground GND, and the other end of the fifth resistor R5 is connected to pin 1 of the first potentiometer W1; pin 3 of the first ordinary precision operational amplifier U1A is connected to one end of the twelfth resistor R12, and the other end of the twelfth resistor R12 is connected to pin 6 of the first instrumentation operational amplifier U2; pin 4 of the first ordinary precision operational amplifier U1A is connected to the input -12V DC power supply; pin 8 of the first ordinary precision operational amplifier U1A is connected to the input +12V DC power supply; Pin 1 of the first potentiometer W1 is connected to the fifth resistor R5, and pins 2 and 3 of the first potentiometer W1 are connected in parallel to pin 1 of the first common precision operational amplifier U1A, for adjusting the gain or bias of the amplifier; The fifth capacitor C5 and the eighth capacitor C8 are used as filter capacitors of the positive and negative power supplies respectively, and the other ends thereof are connected to the power ground GND; The fifth resistor R5 and the eleventh resistor R11 are used as bias and current limiting resistors at the input end; The twelfth resistor R12 is used as a signal transmission resistor connecting the first-stage amplifying circuit module 10 and the second-stage amplifying circuit module 20 .

[0024] In some embodiments, the output end of the secondary amplifier circuit module 20 is directly transmitted to the input end of the adding circuit module 30 through an internal connection, and the adding circuit module 30 includes: a second ordinary precision operational amplifier U1B, a second resistor R2, a third resistor R3, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8; Specifically, the adding circuit module 30 modulates the zero-position voltage outputted finally by adding the reference voltage; the second signal outputted by the secondary amplifying circuit module 20 and the reference voltage are inputted into the second common precision operational amplifier U1B through the sixth resistor R6 and the eighth resistor R8; the second resistor R2, the third resistor R3 and the seventh resistor R7 form a feedback network to realize the precise adjustment of the signal; the final output signal is led out through the seventh resistor R7; Among them, the 6th pin of the second ordinary precision operational amplifier U1B is connected to the power ground GND through the second resistor R2 to form a bias of the inverting input terminal; the 7th pin of the second ordinary precision operational amplifier U1B is connected to the node between the 6th pin and the 7th pin of the second ordinary precision operational amplifier U1B through the third resistor R3 to realize the addition operation of the signal; the 5th pin of the second ordinary precision operational amplifier U1B is connected to one end of the eighth resistor R8, and the other end of the eighth resistor R8 is connected to the input reference voltage; the 5th pin of the second ordinary precision operational amplifier U1B is also connected to the 1st pin of the first ordinary precision operational amplifier U1A through the sixth resistor R6 to form feedback of the in-phase input terminal; the 7th pin of the second ordinary precision operational amplifier U1B is used as the output terminal, directly connected to one end of the seventh resistor R7, and the other end of the seventh resistor R7 is used for output signal acquisition (signal after addition operation); The second resistor R2 and the third resistor R3 form a bias and feedback network of the inverting input terminal; The sixth resistor R6 is used as a feedback resistor of the non-inverting input terminal; The seventh resistor R7 is used as an output resistor and is connected to a subsequent circuit or a signal collection point; The eighth resistor R8 is used to set the input of the reference voltage.

[0025] As an example, the specific parameters of the low temperature drift secondary amplifier circuit 100 of the embodiment of the present invention are set as follows: The first common precision operational amplifier U1A and UI8 are of F2284Z type, the first instrument operational amplifier U2 is of FX620GF(Z) type, the first potentiometer W1 is of 3296KW-2K-K type, the second potentiometer W2 is of 3296KW-10K-K type, the first transient voltage suppression diode D1 and the second transient voltage suppression diode D2 are of SMCJ16CA type; The first resistor R1 and the fourth resistor R4 are selected from the RMK2012MB2R0FM model, the second resistor R2, the third resistor R3, and the fifth resistor R5 are selected from the RMK2012YB202BM model, the sixth resistor R6, the eighth resistor R8, the eleventh resistor R11, and the twelfth resistor R12 are selected from the RMK2012YB102BM model, the seventh resistor R7 is selected from the RMK2012YB102BM model, the tenth resistor R10 and the thirteenth resistor R13 are selected from the RMK2012KB101FM model, the fourteenth resistor R14 is selected from the RMK2012EB334BM model, and the fifteenth resistor R15 is selected from the RMK1608YB121FP model; The first capacitor C1, the third capacitor C3, the fifth capacitor C5, the sixth capacitor C6, the eighth capacitor C8, and the ninth capacitor C9 use the model CT41G-0805-X7R-50V-0.1uF-K(N), the second capacitor C2 and the fourth capacitor C4 use the model (G)CT41G-1206-X5R-50V-10uF-M(N), and the seventh capacitor C7 uses the model (G)CT41G-0805-X7R-50V-1uF-K(N).

[0026] Therefore, through the two-stage amplification design, when the sensor signal is input, RC filtering is first performed, and the first instrument operational amplifier U2 first amplifies it by about 412 times, and then amplifies it by 4~5 times through the first ordinary precision operational amplifier U1A, and the two stages amplify it by 1648~2060 times in total; at the same time, the second ordinary precision operational amplifier U1B adds a reference voltage to modulate the final output zero-position voltage. Thus, a high amplification factor of 1500~2000 times is achieved, meeting the signal amplification requirements of airborne sensors; domestic high-performance components are selected, and through careful circuit design, the influence of temperature on the amplification factor and output signal is effectively reduced, ensuring that the circuit works stably in a wide temperature range; through the reference voltage design in the second potentiometer W2 and the addition circuit module 30, the zero-position adjustable function of the output signal is realized, which improves the flexibility and adaptability of the circuit; the addition of transient voltage suppression diodes effectively protects the circuit from damage by transient overvoltage and improves the reliability of the circuit.

[0027] In summary, the low-temperature drift secondary amplifier circuit based on domestic components provided by the embodiment of the present invention is mainly composed of an instrument operational amplifier, an ordinary precision operational amplifier, a wirewound potentiometer, a transient voltage suppression diode, a resistor and a capacitor. The secondary amplifier circuit composed of the instrument operational amplifier and the ordinary precision operational amplifier can achieve an amplification of 1500 to 2000 times, the first potentiometer can adjust the amplification factor, the second potentiometer can adjust the zero position of the sensor, the transient voltage suppression diode is used for circuit protection of the chip, and the resistor and capacitor perform signal filtering. Not only does it achieve the performance requirements of high amplification factor and low temperature drift, it also has additional functions such as adjustable zero position and circuit protection, providing a stable and reliable signal amplification solution for airborne aviation products.

Claims

1. A low temperature drift two-stage amplifier circuit, characterized in that: It includes a primary amplifying circuit module, a secondary amplifying circuit module, and an adding circuit module; the output end of the primary amplifying circuit module is electrically connected to the input end of the secondary amplifying circuit module, and the output end of the secondary amplifying circuit module is electrically connected to the input end of the adding circuit module; The first-stage amplifying circuit module preliminarily amplifies the input signal and outputs a first signal which is transmitted to the second-stage amplifying circuit module; The secondary amplifier circuit module further amplifies the received first signal and outputs a second signal to be transmitted to the addition circuit module; The adding circuit module adds a reference voltage to the received second signal, modulates the zero-position voltage outputted finally, and outputs a final output signal.

2. The low temperature drift two-stage amplifier circuit according to claim 1, characterized in that: The first-stage amplification circuit module includes: a first instrument operational amplifier, a first transient voltage suppression diode, a second transient voltage suppression diode, a second potentiometer, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a sixth capacitor, a seventh capacitor, a ninth capacitor, a first resistor, a fourth resistor, a tenth resistor, a thirteenth resistor, a fourteenth resistor, and a fifteenth resistor; The secondary amplification circuit module includes: a first common precision operational amplifier, a first potentiometer, a fifth capacitor, an eighth capacitor, a fifth resistor, an eleventh resistor, and a twelfth resistor; The adding circuit module includes: a second ordinary precision operational amplifier, a second resistor, a third resistor, a sixth resistor, a seventh resistor, and an eighth resistor.

3. The low temperature drift two-stage amplifier circuit according to claim 2, characterized in that: Pin 1 of the first instrument operational amplifier is connected to pin 8 through the fifteenth resistor to form a feedback loop; pin 2 of the first instrument operational amplifier is respectively connected to the tenth resistor, one end of the sixth capacitor and one end of the seventh capacitor, and the other end of the tenth resistor is connected to the input signal negative terminal S1-; Pin 3 of the first instrument operational amplifier is respectively connected to the thirteenth resistor, one end of the ninth capacitor and the other end of the seventh capacitor, and the other end of the thirteenth resistor is connected to the input signal positive terminal S1+; Pin 4 of the first instrument operational amplifier is connected to one end of the first capacitor and the fourth capacitor through the first resistor, and the other end of the first resistor is connected to the input -12V DC power supply; Pin 5 of the first instrument operational amplifier is directly connected to the power ground GND; Pin 6 of the first instrument operational amplifier is connected to one end of the twelfth resistor, and the other end of the twelfth resistor is connected to the input end of the secondary amplifier circuit module; Pin 7 of the first instrument operational amplifier is connected to one end of the second capacitor and the third capacitor through the fourth resistor, the other ends of the second capacitor and the third capacitor are connected to the power ground GND, and the other end of the fourth resistor is connected to the input +12V DC power supply; Pin 8 of the first instrument operational amplifier is connected to pin 1 through the fifteenth resistor.

4. The low temperature drift two-stage amplifier circuit according to claim 3, characterized in that: One end of the first transient voltage suppression diode is connected to the input signal negative terminal S1-, and the other end is connected to the power ground GND, so as to protect the circuit from the influence of negative transient voltage; One end of the second transient voltage suppression diode is connected to the input signal positive terminal S1+, and the other end is connected to the power ground GND, which is used to protect the circuit from the influence of forward transient voltage; The pin 1 of the second potentiometer is connected to the negative terminal S1- of the input signal, the pin 2 is connected to the positive terminal S1+ of the input signal, and the pin 3 is connected to the power ground GND through the fourteenth resistor, which is used to adjust the attenuation or gain of the input signal; The first capacitor, the second capacitor, the third capacitor and the fourth capacitor are respectively used as filter capacitors, and the other ends of the capacitors are connected to the power ground GND to filter out high-frequency noise in the power supply or signal; The sixth capacitor and the ninth capacitor are used as decoupling capacitors, respectively connected between the 2nd and 3rd pins of the first instrument operational amplifier and the power ground GND to reduce the influence of power supply fluctuations on the amplifier performance; The seventh capacitor is connected across the 2nd and 3rd pins of the first instrument operational amplifier, serving as a coupling capacitor of the differential input terminal; The first resistor and the fourth resistor are used as current limiting resistors, and are respectively connected between the first capacitor, the fourth capacitor, the second capacitor, the third capacitor and the corresponding DC power supply; The tenth resistor and the thirteenth resistor are used as output resistors and are respectively connected between the 2nd and 3rd pins of the first instrument operational amplifier and the input signal terminals S1- and S1+; The fourteenth resistor cooperates with the second potentiometer to adjust the bias of the input signal; The fifteenth resistor is used as a feedback resistor and is connected between pins 1 and 8 of the first instrumentation operational amplifier to set the gain of the amplifier.

5. The low temperature drift two-stage amplifier circuit according to claim 2, characterized in that: Pin 1 of the first ordinary precision operational amplifier is connected to pin 5 of the second ordinary precision operational amplifier through a sixth resistor to form feedback of the common-phase input terminal; pin 2 of the first ordinary precision operational amplifier is respectively connected to one end of the eleventh resistor and the fifth resistor, the other end of the eleventh resistor is connected to the power ground GND, and the other end of the fifth resistor is connected to pin 1 of the first potentiometer; pin 3 of the first ordinary precision operational amplifier is connected to one end of the twelfth resistor, and the other end of the twelfth resistor is connected to pin 6 of the first instrumentation operational amplifier; pin 4 of the first ordinary precision operational amplifier is connected to an input -12V DC power supply; pin 8 of the first ordinary precision operational amplifier is connected to an input +12V DC power supply.

6. The low temperature drift two-stage amplifier circuit according to claim 5, characterized in that: Pin 1 of the first potentiometer is connected to a fifth resistor, and pins 2 and 3 of the first potentiometer are connected in parallel to pin 1 of a first common precision operational amplifier, for adjusting the gain or bias of the amplifier; The fifth capacitor and the eighth capacitor are used as filter capacitors of the positive and negative power supplies respectively, and the other ends thereof are connected to the power ground GND; The fifth resistor and the eleventh resistor serve as bias and current limiting resistors at the input end; The twelfth resistor is used as a signal transmission resistor connecting the primary amplifying circuit module and the secondary amplifying circuit module.

7. The low temperature drift two-stage amplifier circuit according to claim 2, characterized in that: Pin 6 of the second ordinary precision operational amplifier is connected to the power ground GND through the second resistor to form a bias for the inverting input terminal; pin 7 of the second ordinary precision operational amplifier is connected to the node between pin 6 and pin 7 of the second ordinary precision operational amplifier through the third resistor to realize signal addition operation; pin 5 of the second ordinary precision operational amplifier is connected to one end of the eighth resistor, and the other end of the eighth resistor is connected to the input reference voltage; pin 5 of the second ordinary precision operational amplifier is also connected to pin 1 of the first ordinary precision operational amplifier through the sixth resistor to form feedback for the in-phase input terminal; pin 7 of the second ordinary precision operational amplifier is used as the output terminal, directly connected to one end of the seventh resistor, and the other end of the seventh resistor is used to output the final output signal.

8. The low temperature drift two-stage amplifier circuit according to claim 7, characterized in that: The second resistor and the third resistor form a bias and feedback network of the inverting input terminal; the sixth resistor serves as a feedback resistor of the non-inverting input terminal; and the seventh resistor serves as an output resistor; The eighth resistor is used to limit the input of the reference voltage.

9. The low temperature drift two-stage amplifier circuit according to claim 2, characterized in that: The first-stage amplifier circuit module is specifically used for: The input signal is protected by a first transient voltage suppression diode and a second transient voltage suppression diode and then connected to the input end of the first instrument operational amplifier; The first capacitor, the second capacitor, the third capacitor, the fourth capacitor, the first resistor and the fourth resistor form a power filter network to ensure power stability; The sixth capacitor, the seventh capacitor, the ninth capacitor cooperate with the tenth resistor, the thirteenth resistor, and the fifteenth resistor to achieve signal filtering and amplification; The second potentiometer is used to adjust the zero position of the input signal.

10. The low temperature drift two-stage amplifier circuit according to claim 2, characterized in that: The secondary amplifier circuit module is specifically used for: Connecting the received first signal to the input end of the first common precision operational amplifier through the twelfth resistor; The fifth capacitor, the eighth capacitor, the fifth resistor and the eleventh resistor form a power supply filter network; The first potentiometer is used to adjust the amplification factor; The adding circuit module is specifically used for: Input the received second signal and the set reference voltage into the second common precision operational amplifier through the sixth resistor and the eighth resistor; The second resistor, the third resistor and the seventh resistor form a feedback network to achieve accurate adjustment of the signal; The final output signal is led out through the seventh resistor.

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