阅读说明：本技术 一种航空高精度模拟量采集系统的全增益放大电路 (Full-gain amplification circuit of aviation high-precision analog quantity acquisition system ) 是由 车炯晖 呼明亮 於二军 李阳 刘夏青 于 2021-09-01 设计创作，主要内容包括：本发明公开一种航空高精度模拟量采集系统的全增益放大电路,包括：两个相同的三仪表运放,两个增益电阻；其中,每个三仪表运放的输入正端与输入负端短接,其中一个运放的输入为全增益放大电路的输入正端,另一个运放的输入为全增益放大电路的输入负端；全增益放大电路具有两路输出,为两个三仪表运放的输出；两个增益电阻分别跨接在两个三仪表运放的增益配置引脚上,使得全增益放大电路的两路输出增益倍数由两个增益电阻共同实现。本发明的技术方案,解决了现有三运放仪表放大器的增益系数范围较为有限,使得很多高精度的应用场景无法使用的问题。(The invention discloses a full-gain amplifying circuit of an aviation high-precision analog quantity acquisition system, which comprises: two identical three-instrument operational amplifiers and two gain resistors; the input positive end of each three-meter operational amplifier is in short circuit with the input negative end, the input of one operational amplifier is the input positive end of the full-gain amplification circuit, and the input of the other operational amplifier is the input negative end of the full-gain amplification circuit; the full-gain amplification circuit is provided with two paths of outputs, namely the outputs of two three-instrument operational amplifiers; the two gain resistors are respectively bridged on the gain configuration pins of the two three-meter operational amplifiers, so that the two-path output gain multiples of the full-gain amplifying circuit are jointly realized by the two gain resistors. The technical scheme of the invention solves the problem that the gain coefficient range of the existing three-operational amplifier instrument amplifier is limited, so that a plurality of high-precision application scenes cannot be used.)

1. The utility model provides a full gain amplifier circuit of high accuracy analog acquisition system of aviation which characterized in that includes: two identical three-instrument operational amplifiers and two gain resistors;

the input positive end of each three-instrument operational amplifier is in short circuit with the input negative end, the input of one three-instrument operational amplifier is the input positive end of the full-gain amplification circuit, and the input of the other three-instrument operational amplifier is the input negative end of the full-gain amplification circuit; the full-gain amplification circuit is provided with two paths of outputs, namely the outputs of two three-instrument operational amplifiers;

the two gain resistors are respectively bridged on the gain configuration pins of the two three-meter operational amplifiers, so that the two-path output gain multiples of the full-gain amplifying circuit are jointly realized by the two gain resistors.

2. The full-gain amplification circuit of the aviation high-precision analog quantity acquisition system according to claim 1, wherein each three-instrument operational amplifier comprises a first gain configuration pin and a second gain configuration pin; the two three-meter operational amplifiers respectively comprise a first meter operational amplifier and a second meter operational amplifier, and the two gain resistors are a first gain resistor (R3) and a second gain resistor (R4);

the two gain resistors are respectively bridged on gain configuration pins of the two three-meter operational amplifiers, and the two gain resistors refer to the following steps:

one end of a first gain resistor (R3) is connected with a first gain configuration pin of the first instrument operational amplifier, and the other end of the first gain resistor is connected with a first gain configuration pin of the second instrument operational amplifier;

one end of the second gain resistor is connected to a second gain configuration pin of the first instrument operational amplifier, and the other end of the second gain resistor is connected to a second gain configuration pin of the second instrument operational amplifier.

3. The full-gain amplification circuit of the aviation high-precision analog quantity acquisition system according to claim 2, wherein each three-instrument operational amplifier comprises a first input-stage operational amplifier (A1), a second input-stage operational amplifier (A2) and an output-stage operational amplifier (A3), the output end of the first input-stage operational amplifier (A1) is connected to the negative input end of the output-stage operational amplifier (A3), and the output end of the second input-stage operational amplifier (A2) is connected to the positive input end of the output-stage operational amplifier (A3);

two ends of the first gain resistor (R3) are respectively connected with the first input stage operational amplifier (A1) of the two three-meter operational amplifiers, and two ends of the second gain resistor (R4) are respectively connected with the second input stage operational amplifier (A2) of the two three-meter operational amplifiers; each input stage operational amplifier of each three-meter operational amplifier respectively reaches a deep negative feedback state with the input positive end and the input negative end of the full-gain amplification circuit, so that the current on the feedback path is almost 0, and the voltage loss in the feedback path is close to 0.

4. The full-gain amplification circuit of the aviation high-precision analog quantity acquisition system according to any one of claims 1 to 3,

the two outputs of the full-gain amplifying circuit are opposite numbers and have the same gain multiple.

5. The full-gain amplification circuit of the aviation high-precision analog quantity acquisition system according to claim 4, wherein the output end of the first input stage operational amplifier (A1) of each three-instrument operational amplifier is connected in series with a first resistor (R1), the output end of the second input stage operational amplifier (A2) is connected in series with a second resistor (R2), and R1-R2-R;

the voltage (V1) at the connection part of the first gain resistor (R3) and the first instrument operational amplifier and the voltage (V1') at the connection part of the second gain resistor (R4) and the first instrument operational amplifier are both equal to the voltage value (Vin +) of the input positive terminal of the full-gain amplification circuit;

the voltage (V3) at the connection part of the first gain resistor (R3) and the second instrument operational amplifier and the voltage (V3') at the connection part of the second gain resistor (R4) and the second instrument operational amplifier are both equal to the voltage value (Vin-) of the input negative terminal of the full-gain amplification circuit.

6. The full-gain amplification circuit of the aviation high-precision analog quantity acquisition system according to claim 5,

at V_REFAnd when Vin-is 0V, the two outputs of the full-gain amplifying circuit are respectively as follows:

at V_REFAnd when Vin + is 0V, the two outputs of the full-gain amplifier circuit are respectively:

wherein, V₂Is the voltage at the output of a first input stage operational amplifier (A1) in a first instrumentation operational amplifier, V₂' is the output terminal voltage of a second input stage operational amplifier (A2) in the first instrument operational amplifier; v₄Is the output voltage, V, of a first input stage operational amplifier (A1) in a second instrumentation operational amplifier₄' is the output voltage of a second input stage operational amplifier (A2) in the second instrumentation operational amplifier.

7. The full-gain amplification circuit of the aviation high-precision analog quantity acquisition system according to claim 6,

according to V_REFAnd Vin-is both 0V, and V_REFAnd the sum Vin + is two outputs of the full-gain amplifying circuit under the condition of 0V, and the two outputs of the full-gain amplifying circuit under any condition are obtained as follows:

8. the full-gain amplification circuit of an aviation high-precision analog quantity acquisition system according to claim 7,

the output gain of the full-gain amplifying circuit is as follows: R/R₃-R/R₄；

The gain multiple of the full-gain amplifying circuit is a value from minus infinity to plus infinity by adjusting the resistance values of the first gain resistor (R3) and the second gain resistor (R4).

Technical Field

The invention relates to the technical field of airborne analog quantity acquisition, in particular to a full-gain amplification circuit of an aviation high-precision analog quantity acquisition system.

Background

The electromechanical system of the airplane comprises a large number of analog quantity signals of temperature, humidity, flow, pressure, liquid level, rotating speed and the like, and the requirements on the measurement precision, the acquisition speed and the data stability of the electromechanical system of the airplane are higher and higher.

The instrument operational amplifier in the analog circuit has the advantages of high common mode rejection ratio, high input impedance, low noise, low linearity error, low offset voltage, low input bias current and the like, and occupies a very important position in the analog circuit of the aircraft electromechanical system. The high-precision amplification circuit with a large gain range is necessary for improving the signal monitoring precision of the electromechanical system.

The commonly used three-operational-amplifier instrumentation amplifier at present has the advantages of high common-mode rejection ratio, high input impedance, low noise, low linearity error, low offset voltage, low input bias current and the like. However, the gain coefficient range of the triple operational amplifier instrumentation amplifier is limited, so that many high-precision application scenes have to be realized by using a common operational amplifier, which does not have the advantages of the instrumentation operational amplifier.

Disclosure of Invention

The purpose of the invention is as follows: in order to solve the problems in the background art, the embodiment of the invention provides a full-gain amplification circuit of an aviation high-precision analog quantity acquisition system, so as to solve the problem that a plurality of high-precision application scenes cannot be used due to the fact that the gain coefficient range of the existing three operational amplifier instrument amplifier is limited.

The technical scheme of the invention is as follows: the embodiment of the invention provides a full-gain amplification circuit of an aviation high-precision analog quantity acquisition system, which comprises: two identical three-instrument operational amplifiers and two gain resistors;

the input positive end of each three-instrument operational amplifier is in short circuit with the input negative end, the input of one three-instrument operational amplifier is the input positive end of the full-gain amplification circuit, and the input of the other three-instrument operational amplifier is the input negative end of the full-gain amplification circuit; the full-gain amplification circuit is provided with two paths of outputs, namely the outputs of two three-instrument operational amplifiers;

the two gain resistors are respectively bridged on the gain configuration pins of the two three-meter operational amplifiers, so that the two-path output gain multiples of the full-gain amplifying circuit are jointly realized by the two gain resistors.

Optionally, in the full-gain amplification circuit of the aviation high-precision analog quantity acquisition system, each of the three instrument operational amplifiers includes a first gain configuration pin and a second gain configuration pin; the two three-meter operational amplifiers respectively comprise a first meter operational amplifier and a second meter operational amplifier, and the two gain resistors are a first gain resistor (R3) and a second gain resistor (R4);

the two gain resistors are respectively bridged on gain configuration pins of the two three-meter operational amplifiers, and the two gain resistors refer to the following steps:

one end of a first gain resistor (R3) is connected with a first gain configuration pin of the first instrument operational amplifier, and the other end of the first gain resistor is connected with a first gain configuration pin of the second instrument operational amplifier;

one end of the second gain resistor is connected to a second gain configuration pin of the first instrument operational amplifier, and the other end of the second gain resistor is connected to a second gain configuration pin of the second instrument operational amplifier.

Optionally, in the full-gain amplification circuit of the aviation high-precision analog quantity acquisition system as described above, each of the three instrument operational amplifiers includes a first input stage operational amplifier (a1), a second input stage operational amplifier (a2) and an output stage operational amplifier (A3), an output end of the first input stage operational amplifier (a1) is connected to an input negative end of the output stage operational amplifier (A3), and an output end of the second input stage operational amplifier (a2) is connected to an input positive end of the output stage operational amplifier (A3);

two ends of the first gain resistor (R3) are respectively connected with the first input stage operational amplifier (A1) of the two three-meter operational amplifiers, and two ends of the second gain resistor (R4) are respectively connected with the second input stage operational amplifier (A2) of the two three-meter operational amplifiers; each input stage operational amplifier of each three-meter operational amplifier respectively reaches a deep negative feedback state with the input positive end and the input negative end of the full-gain amplification circuit, so that the current on the feedback path is almost 0, and the voltage loss in the feedback path is close to 0.

Optionally, in the full-gain amplifying circuit of the aviation high-precision analog quantity acquisition system,

the two outputs of the full-gain amplifying circuit are opposite numbers and have the same gain multiple.

Optionally, in the full-gain amplification circuit of the aviation high-precision analog quantity acquisition system, an output end of a first input stage operational amplifier (a1) of each three-instrument operational amplifier is connected in series with a first resistor (R1), an output end of a second input stage operational amplifier (a2) is connected in series with a second resistor (R2), and R1-R2-R;

the voltage (V1) at the connection part of the first gain resistor (R3) and the first instrument operational amplifier and the voltage (V1') at the connection part of the second gain resistor (R4) and the first instrument operational amplifier are both equal to the voltage value (Vin +) of the input positive terminal of the full-gain amplification circuit;

the voltage (V3) at the connection part of the first gain resistor (R3) and the second instrument operational amplifier and the voltage (V3') at the connection part of the second gain resistor (R4) and the second instrument operational amplifier are both equal to the voltage value (Vin-) of the input negative terminal of the full-gain amplification circuit.

Optionally, in the full-gain amplifying circuit of the aviation high-precision analog quantity acquisition system,

at V_REFAnd when Vin-is 0V, the two outputs of the full-gain amplifying circuit are respectively as follows:

at V_REFAnd when Vin + is 0V, the two outputs of the full-gain amplifier circuit are respectively:

wherein, V₂Is the voltage at the output of a first input stage operational amplifier (A1) in a first instrumentation operational amplifier, V₂' is the output terminal voltage of a second input stage operational amplifier (A2) in the first instrument operational amplifier; v₄Is the output voltage, V, of a first input stage operational amplifier (A1) in a second instrumentation operational amplifier₄' is the output voltage of a second input stage operational amplifier (A2) in the second instrumentation operational amplifier.

Optionally, in the full-gain amplifying circuit of the aviation high-precision analog quantity acquisition system,

according to V_REFAnd Vin-is both 0V, and V_REFAnd the sum Vin + is two outputs of the full-gain amplifying circuit under the condition of 0V, and the two outputs of the full-gain amplifying circuit under any condition are obtained as follows:

optionally, in the full-gain amplification circuit of the aviation high-precision analog quantity acquisition system, the output gain of the full-gain amplification circuit is as follows: R/R₃-R/R₄；

The gain multiple of the full-gain amplifying circuit is a value from minus infinity to plus infinity by adjusting the resistance values of the first gain resistor (R3) and the second gain resistor (R4).

The invention has the beneficial effects that: the embodiment of the invention provides a full-gain amplification circuit of an aviation high-precision analog quantity acquisition system, which is formed by two identical three-instrument operational amplifiers and two gain resistors, wherein the input positive end and the input negative end of each three-instrument operational amplifier are in short circuit, and the two gain resistors are respectively bridged on gain configuration pins of the two three-instrument operational amplifiers, so that two paths of output gain multiples of the formed full-gain amplification circuit are jointly realized by the two gain resistors; finally, the gain multiple of the full-gain amplifying circuit can be realized to be a value from negative infinity to positive infinity by adjusting the resistance values of the first gain resistor (R3) and the second gain resistor (R4). By adopting the full-gain amplifying circuit provided by the embodiment of the invention, the normalization and high precision of the operational amplifying circuit of the analog quantity acquisition system of the aircraft electromechanical system are realized, the BIT method is simpler, and only the outputs of two operational amplifiers need to be added; in addition, under the condition of not interfering with the normal acquisition function, higher detection coverage rate is realized.

Description of the drawings:

fig. 1 is a schematic structural diagram of a full-gain amplification circuit of an aviation high-precision analog quantity acquisition system according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a full-gain amplification circuit of the aviation high-precision analog quantity acquisition system provided in the embodiment shown in fig. 1.

The specific implementation mode is as follows:

in order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.

The steps illustrated in the flow charts of the figures may be performed in a computer system such as a set of computer-executable instructions. Also, while a logical order is shown in the flow diagrams, in some cases, the steps shown or described may be performed in an order different than here.

As described in the above background art, the commonly used three-operational amplifier instrumentation amplifier has the advantages of high common mode rejection ratio, high input impedance, low noise, low linearity error, low offset voltage, and low input bias current. However, the gain coefficient range of the conventional common three-operational amplifier instrument amplifier is relatively limited, so that many high-precision application scenes have to be realized by using a common operational amplifier, and the common operational amplifier does not have the advantages of the instrument operational amplifier.

Aiming at the problems of the common three-operational-amplifier instrument amplifier, the embodiment of the invention provides a full-gain amplification circuit of an aviation high-precision analog quantity acquisition system, which aims to solve the problem that the gain coefficient range of the conventional three-operational-amplifier instrument amplifier is limited, so that a plurality of high-precision application scenes cannot be used.

The following specific embodiments of the present invention may be combined, and the same or similar concepts or processes may not be described in detail in some embodiments.

Fig. 1 is a schematic structural diagram of a full-gain amplification circuit of an aviation high-precision analog quantity acquisition system in an embodiment of the invention. The full-gain amplification circuit provided by the embodiment of the invention can comprise: two identical three-meter operational amplifiers and two gain resistors.

In the structure of the full-gain amplifier circuit shown in fig. 1, the positive input terminal (Vin +) of each three-meter operational amplifier is shorted with the negative input terminal (Vin-), wherein the input of one three-meter operational amplifier is the positive input terminal (Vin +) of the full-gain amplifier circuit shown in fig. 1, and the input of the other three-meter operational amplifier is the negative input terminal (Vin-) of the full-gain amplifier circuit shown in fig. 1, such as the negative input terminal (Vin-) of the three-meter operational amplifier circuit shown in fig. 1. The full-gain amplification circuit formed by the two three-meter operational amplifiers has two paths of outputs, specifically the outputs of the two three-meter operational amplifiers.

In the full-gain amplification circuit provided by the embodiment of the invention, the two gain resistors are respectively bridged on the gain configuration pins of the two three-meter operational amplifiers, so that the two-path output gain multiples of the full-gain amplification circuit are jointly realized by the two gain resistors.

It should be noted that the full-gain amplification circuit according to the embodiment of the present invention adopts two output paths, that is, Vout1 and Vout2 in fig. 1, and can adopt one output path as a monitoring circuit of the other output path, that is, a BIT circuit, without adding an additional hardware circuit, and by superimposing the outputs of two operational amplifiers, it is only necessary to add the outputs of two operational amplifiers.

Referring to the structure of the full-gain amplification circuit shown in fig. 1, each three-meter operational amplifier includes a first gain configuration pin and a second gain configuration pin; the two three-meter operational amplifiers respectively comprise a first meter operational amplifier and a second meter operational amplifier, and the two gain resistors are a first gain resistor (R3) and a second gain resistor (R4).

In the embodiment of the invention, the specific bridging mode that two gain resistors are respectively bridged on the gain configuration pins of two three-meter operational amplifiers is as follows:

one end of a first gain resistor (R3) is connected with a first gain configuration pin (GS1-1) of the first instrument operational amplifier, and the other end of the first gain resistor is connected with a first gain configuration pin (GS2-1) of the second instrument operational amplifier;

one end of the second gain resistor (R4) is connected with a second gain configuration pin (GS1-2) of the first instrument operational amplifier, and the other end is connected with a second gain configuration pin (GS2-2) of the second instrument operational amplifier.

Optionally, fig. 2 is a schematic diagram of a specific structure of a full-gain amplification circuit of the aviation high-precision analog quantity acquisition system provided in the embodiment shown in fig. 1, and a specific structure of each three-instrument operational amplifier is schematically shown in fig. 2. In the structure of the full-gain amplifying circuit shown in fig. 2, each three-meter operational amplifier comprises a first input stage operational amplifier (a1), a second input stage operational amplifier (a2) and an output stage operational amplifier (A3); and in each three-meter operational amplifier, the output end of the first input stage operational amplifier (A1) is connected to the negative input end of the output stage operational amplifier (A3), and the output end of the second input stage operational amplifier (A2) is connected to the positive input end of the output stage operational amplifier (A3).

As shown in fig. 2, two ends of the first gain resistor (R3) are respectively connected to the first input stage operational amplifier (a1) of the two three-meter operational amplifiers, and two ends of the second gain resistor (R4) are respectively connected to the second input stage operational amplifier (a2) of the two three-meter operational amplifiers; each input stage operational amplifier of each three-meter operational amplifier respectively reaches a deep negative feedback state with the input positive end and the input negative end of the full-gain amplification circuit, so that the current on the feedback path is almost 0, and the voltage loss in the feedback path is close to 0.

It should be noted that, in the full-gain amplification circuit provided in the embodiment of the present invention, the two outputs (i.e., Vout1 and Vout2) are opposite numbers, and the gain multiples are the same.

In the structure of the full-gain amplifying circuit shown in fig. 2, the output end of the first input stage operational amplifier (a1) of each three-meter operational amplifier is connected in series with a first resistor (R1), the output end of the second input stage operational amplifier (a2) is connected in series with a second resistor (R2), and R1-R2-R.

In addition, the voltage (V1) at the connection part of the first gain resistor (R3) and the first instrument operational amplifier and the voltage (V1') at the connection part of the second gain resistor (R4) and the first instrument operational amplifier are equal to the voltage value (Vin +) of the input positive terminal of the full-gain amplification circuit.

The voltage (V3) at the connection part of the first gain resistor (R3) and the second instrument operational amplifier and the voltage (V3') at the connection part of the second gain resistor (R4) and the second instrument operational amplifier are equal to the voltage value (Vin-) of the input negative terminal of the full-gain amplification circuit.

Based on the circuit structure of the full-gain amplification circuit, the voltage value and the resistance setting in the circuit, the full-gain amplification circuit has the following characteristics:

at V_REFAnd when Vin-is 0V, the two outputs of the full-gain amplifying circuit are respectively as follows:

under the condition that VREF and Vin + are both 0V, two outputs of the full-gain amplifying circuit are respectively as follows:

in the above formula, V₂Is the voltage at the output of a first input stage operational amplifier (A1) in a first instrumentation operational amplifier, V₂' is the output terminal voltage of a second input stage operational amplifier (A2) in the first instrument operational amplifier; v₄Is the output voltage, V, of a first input stage operational amplifier (A1) in a second instrumentation operational amplifier₄' is the output voltage of a second input stage operational amplifier (A2) in the second instrumentation operational amplifier.

Further, according to V_REFAnd Vin-is both 0V, and V_REFAnd two outputs of the full-gain amplifying circuit under the condition that Vin + is 0V, namely, two outputs of the full-gain amplifying circuit under any condition are obtained according to the above equations (1) and (2):

it should be noted that, as can be seen from the above description, the output gain of the full-gain amplifier circuit provided in the embodiment of the present invention is specifically: R/R₃-R/R₄。

Since the calculation manner of the output gain of the full-gain amplification circuit is known, the gain multiple of the full-gain amplification circuit can be a value from minus infinity to plus infinity by adjusting the resistance values of the first gain resistor (R3) and the second gain resistor (R4).

The embodiment of the invention provides a full-gain amplification circuit of an aviation high-precision analog quantity acquisition system, which is formed by two identical three-instrument operational amplifiers and two gain resistors, wherein the input positive end and the input negative end of each three-instrument operational amplifier are in short circuit, and the two gain resistors are respectively bridged on gain configuration pins of the two three-instrument operational amplifiers, so that two paths of output gain multiples of the formed full-gain amplification circuit are jointly realized by the two gain resistors; finally, the gain multiple of the full-gain amplifying circuit can be realized to be a value from negative infinity to positive infinity by adjusting the resistance values of the first gain resistor (R3) and the second gain resistor (R4). By adopting the full-gain amplifying circuit provided by the embodiment of the invention, the normalization and high precision of the operational amplifying circuit of the analog quantity acquisition system of the aircraft electromechanical system are realized, the BIT method is simpler, and only the outputs of two operational amplifiers need to be added; in addition, under the condition of not interfering with the normal acquisition function, higher detection coverage rate is realized.

The following describes a specific implementation of the full-gain amplification circuit of the aviation high-precision analog quantity acquisition system according to an embodiment of the present invention with a specific implementation example.

Referring to the structure of the full-gain amplifier circuit shown in fig. 2, the circuit specifically includes: two identical three-meter operational amplifiers and two gain resistors. The input positive end (Vin +) of each three-meter operational amplifier is in short circuit with the input negative end (Vin-), wherein the input of one three-meter operational amplifier is the input positive end of the full-gain amplifier circuit, the input of the other three-meter operational amplifier circuit is the input negative end of the full-gain amplifier circuit, and the two gain resistors are respectively bridged on the gain configuration pins of the two three-meter operational amplifiers; specifically, the two gain resistors are respectively connected with the internal input stage operational amplifiers of the three-instrument operational amplifier, so that each input stage operational amplifier of each three-instrument operational amplifier respectively achieves a deep negative feedback state with the input positive end and the input negative end. And then analog signals are output through the output stage operational amplifiers of the two three-instrument operational amplifiers. The specific connection of the circuit has already been described in the above embodiments, and therefore, the detailed description thereof is omitted here. In addition, for a three-meter operational amplifier with a reference end, the reference end needs to be grounded.

Taking an AD620 type three-meter operational amplifier as an example for explanation, R1 and R2 in FIG. 2 are equal and equal to 24.7k omega; set V_REFAnd Vin-is 0V, then:

v1 ═ V1 ═ Vin +, V3 ═ V3 ═ Vin ═ 0. Let R1 ═ R2 ═ R, therefore, one can obtain:

V_REFand Vin-is 0V, the output of the two three operational amplifier instruments can be calculated by the formula (4), the output of the upper three operational amplifier instruments 1 is Vout1, and the output of the lower three operational amplifier instruments 2 is Vout2, then the calculation formula of the output can be obtained:

the symmetry of the operational amplifier of two three meters shows that when V is_REFAnd when Vin + is 0V, the calculation formula for obtaining the output is:

then, according to the superposition theorem, the formula (1) and the formula (2) are superposed to obtain the formula (3), when V is_REFAt 0V, the calculation formula for obtaining the output is:

since R is equal to 24.7k Ω, the gain multiple of the circuit can be from negative infinity to positive infinity by selecting the magnitudes of R3 and R4. For example, selecting R3 to be 49.4k Ω and R4 to be 24.7k Ω gives a magnification of. + -. 0.5.

The conclusion obtained by the embodiment of the invention is also true for other types of three-instrument operational amplifiers. For the three-meter operational amplifier with different models, when the internal resistance values of R1 and R2 are equal to other values, the resistance values of the two gain resistors can be obtained by simply calculating again according to the formula.

The circuit has two diametrically opposed outputs that can be used for BIT detection. When BIT detection is carried out, only two paths of outputs are converted into AD code values, the two code values are added, if the two code values are smaller than an allowable error, the test is considered to be passed, and if the two code values are not smaller than the allowable error, the test is considered to be failed.

Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.