CN103762949B - A kind of level shifting circuit for small signal variation detection - Google Patents

Abstract

Translated fromChinese

本发明涉及一种针对小信号变化检测的电平转换电路，其包括：第一运算放大器、第二运算放大器、第三运算放大器、第四运算放大器、第五运算放大器、第一开关、第二开关、第一电阻、第二电阻、第三电阻、第四电阻、第五电阻、可变电阻、和基准电压产生装置。根据本发明的针对小信号变化检测的电平转换电路既可以得到被测量的传感器的输出电压的极性，又能够实现对变化电压的放大，还可以调节和获知放大倍数，从而可以由测量值直接计算得到传感器的输出值。

The present invention relates to a level conversion circuit for small signal change detection, which includes: a first operational amplifier, a second operational amplifier, a third operational amplifier, a fourth operational amplifier, a fifth operational amplifier, a first switch, a second A switch, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a variable resistor, and a reference voltage generating device. According to the level conversion circuit for small signal change detection of the present invention, the polarity of the output voltage of the measured sensor can be obtained, and the amplification of the changing voltage can be realized, and the amplification factor can also be adjusted and known, so that the measured value The output value of the sensor is directly calculated.

Description

Translated fromChinese

一种针对小信号变化检测的电平转换电路A level conversion circuit for small signal change detection

技术领域technical field

本发明涉及电学领域，更具体的，涉及一种针对小信号变化检测的电平转换电路。The present invention relates to the field of electricity, and more specifically, relates to a level conversion circuit for small signal change detection.

背景技术Background technique

在实际使用输出直流信号的传感器过程中，经常会遇到输出电压的变化量随被测量变化较小的情况，如果直接将输出电压放大，则会得到很大的电压，但是我们在实际使用中希望仅放大电压变化的部分。In the process of actually using a sensor that outputs a DC signal, it is often encountered that the variation of the output voltage is small with the measured change. If the output voltage is directly amplified, a large voltage will be obtained, but in our actual use It is desirable to amplify only the portion where the voltage changes.

目前，还没有一种能够放大所述变化量、并且获得该变化量的极性和具体值、并且放大倍数可调节并可知具体放大倍数值的这样电路。At present, there is no such circuit that can amplify the change amount, obtain the polarity and specific value of the change amount, and can adjust the magnification and know the specific magnification value.

发明内容Contents of the invention

为了解决上述技术问题，本发明提供了一种针对小信号变化检测的电平转换电路，其包括：In order to solve the above technical problems, the present invention provides a level conversion circuit for small signal change detection, which includes:

第一运算放大器、第二运算放大器、第三运算放大器、第四运算放大器、第五运算放大器、第一开关、第二开关、第一电阻、第二电阻、第三电阻、第四电阻、第五电阻、可变电阻、和基准电压产生装置，其中第一运算放大器的正相输入端接收输入信号，该第一运算放大器的反相输入端连接其输出端，该第一运算放大器的输出端分别连接第三运算放大器的反相输入端、第四运算放大器的正相输入端和第五运算放大器的正相输入端，该第三运算放大器的正相输入端分别连接第二运算放大器的反相输入端和输出端，该第三运算放大器的输出端输出第一输出信号，该第二运算放大器的正相输入端连接基准电压产生装置，该第二运算放大器的输出端还分别连接第一电阻的一端和第二开关的第一端，该第一电阻的另一端分别连接第二电阻的一端和第四运算放大器的反相输入端，该第四运算放大器的输出端分别连接第二电阻的另一端和第三电阻的第一端，该第三电阻的另一端连接第一开关的一端，该第一开关的另一端分别连接第五运算放大器的反相输入端、第五电阻的一端和可变电阻的滑动触头，该可变电阻的一端连接第四电阻的一端，该第四电阻的另一端连接第二开关的第二端，该第二开关的第三端接地，该第五电阻的另一端连接第五运算放大器的输出端，该第五运算放大器的输出端输出第二输出信号；The first operational amplifier, the second operational amplifier, the third operational amplifier, the fourth operational amplifier, the fifth operational amplifier, the first switch, the second switch, the first resistor, the second resistor, the third resistor, the fourth resistor, the Five resistors, variable resistors, and reference voltage generators, wherein the non-inverting input of the first operational amplifier receives an input signal, the inverting input of the first operational amplifier is connected to its output, and the output of the first operational amplifier Respectively connect the inverting input end of the third operational amplifier, the non-inverting input end of the fourth operational amplifier and the non-inverting input end of the fifth operational amplifier, the non-inverting input end of the third operational amplifier is respectively connected to the inverting input end of the second operational amplifier phase input terminal and output terminal, the output terminal of the third operational amplifier outputs the first output signal, the non-inverting input terminal of the second operational amplifier is connected to the reference voltage generating device, and the output terminals of the second operational amplifier are respectively connected to the first One end of the resistor and the first end of the second switch, the other end of the first resistor is respectively connected to one end of the second resistor and the inverting input end of the fourth operational amplifier, and the output end of the fourth operational amplifier is respectively connected to the second resistor The other end of the third resistor and the first end of the third resistor, the other end of the third resistor is connected to one end of the first switch, and the other end of the first switch is respectively connected to the inverting input end of the fifth operational amplifier and one end of the fifth resistor and the sliding contact of the variable resistor, one end of the variable resistor is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to the second end of the second switch, the third end of the second switch is grounded, and the second end of the fourth resistor is connected to the ground. The other end of the five resistors is connected to the output terminal of the fifth operational amplifier, and the output terminal of the fifth operational amplifier outputs the second output signal;

其中基准电压产生装置提供的基准电压等于待测量的传感器的静态工作电压；Wherein the reference voltage provided by the reference voltage generating device is equal to the static working voltage of the sensor to be measured;

其中第一电阻、第二电阻、第三电阻和第五电阻之间的阻值关系为：Wherein the resistance relationship among the first resistor, the second resistor, the third resistor and the fifth resistor is:

$\frac{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>2</span>2</span>}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>1</span>1</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>3</span>3</span>}}<span><span>=</span>=</span>\frac{\mathrm{<span><span>1</span>1</span>}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>5</span>5</span>}}<span><span>,</span>,</span>$

其中R1表示第一电阻的阻值，R2表示第二电阻的阻值，R3表示第三电阻的阻值，R5表示第五电阻的阻值。Wherein R1 represents the resistance value of the first resistor, R2 represents the resistance value of the second resistor, R3 represents the resistance value of the third resistor, and R5 represents the resistance value of the fifth resistor.

其中第一开关是单刀单掷开关，第二开关是单刀双掷开关。Wherein the first switch is a single-pole single-throw switch, and the second switch is a single-pole double-throw switch.

通过本发明的针对小信号变化检测的电平转换电路既可以得到被测量的传感器的输出电压Uin的极性，又能够通过使用与传感器的静态输出电压相等的电压作为基准电压，并且设置合适的电阻值，实现对变化电压ΔV的放大，还可以调节和获知放大倍数，从而可以由测量值直接计算得到传感器的输出值Uin。该针对小信号变化检测的电平转换电路的测量误差小，方便实用。The polarity of the output voltage Uin of the sensor to be measured can be obtained through the level conversion circuit for small signal change detection of the present invention, and the voltage equal to the static output voltage of the sensor can be used as a reference voltage, and a suitable voltage can be set. The resistance value realizes the amplification of the changing voltage ΔV, and can also adjust and know the amplification factor, so that the output value Uin of the sensor can be directly calculated from the measured value. The level conversion circuit for small signal change detection has small measurement error, and is convenient and practical.

附图说明Description of drawings

图1是本发明的针对小信号变化检测的电平转换电路的原理示意图。FIG. 1 is a schematic diagram of the principle of a level conversion circuit for small signal change detection according to the present invention.

具体实施方式detailed description

图1是本发明的针对小信号变化检测的电平转换电路的原理示意图。如图所示，该针对小信号变化检测的电平转换电路包括：FIG. 1 is a schematic diagram of the principle of a level conversion circuit for small signal change detection according to the present invention. As shown in the figure, the level conversion circuit for small signal change detection includes:

第一运算放大器A1、第二运算放大器A2、第三运算放大器A3、第四运算放大器A4、第五运算放大器A5、第一开关S1、第二开关S2、第一电阻R1、第二电阻R2、第三电阻R3、第四电阻R4、第五电阻R5、可变电阻R6、和基准电压产生装置，其中第一运算放大器的正相输入端接收输入信号Uin，该第一运算放大器的反相输入端连接其输出端，该第一运算放大器的输出端分别连接第三运算放大器A3的反相输入端、第四运算放大器A4的正相输入端和第五运算放大器的正相输入端，该第三运算放大器A3的正相输入端分别连接第二运算放大器A2的反相输入端和输出端，该第三运算放大器A3的输出端输出第一输出信号Uout1，该第二运算放大器A2的正相输入端连接基准电压产生装置，该第二运算放大器A2的输出端还分别连接第一电阻R1的一端和第二开关S2的第一端，该第一电阻R1的另一端分别连接第二电阻R2的一端和第四运算放大器A4的反相输入端，该第四运算放大器A4的输出端分别连接第二电阻R2的另一端和第三电阻R3的第一端，该第三电阻R3的另一端连接第一开关S1的一端，该第一开关S1的另一端分别连接第五运算放大器A5的反相输入端、第五电阻R5的一端和可变电阻R6的滑动触头，该可变电阻R6的一端连接第四电阻R4的一端，该第四电阻R4的另一端连接第二开关S2的第二端，该第二开关S2的第三端接地，该第五电阻R5的另一端连接第五运算放大器A5的输出端，该第五运算放大器A5的输出端输出第二输出信号Uout2。The first operational amplifier A1, the second operational amplifier A2, the third operational amplifier A3, the fourth operational amplifier A4, the fifth operational amplifier A5, the first switch S1, the second switch S2, the first resistor R1, the second resistor R2, The third resistor R3, the fourth resistor R4, the fifth resistor R5, the variable resistor R6, and the reference voltage generating device, wherein the non-inverting input terminal of the first operational amplifier receives the input signal Uin, and the inverting input terminal of the first operational amplifier terminal is connected to its output terminal, and the output terminal of the first operational amplifier is respectively connected to the inverting input terminal of the third operational amplifier A3, the non-inverting input terminal of the fourth operational amplifier A4 and the non-inverting input terminal of the fifth operational amplifier. The non-inverting input terminals of the three operational amplifiers A3 are respectively connected to the inverting input terminal and the output terminal of the second operational amplifier A2, the output terminal of the third operational amplifier A3 outputs the first output signal Uout1, and the non-inverting input terminal of the second operational amplifier A2 The input end is connected to the reference voltage generating device, the output end of the second operational amplifier A2 is also respectively connected to one end of the first resistor R1 and the first end of the second switch S2, and the other end of the first resistor R1 is respectively connected to the second resistor R2 One terminal of the fourth operational amplifier A4 and the inverting input terminal of the fourth operational amplifier, the output terminal of the fourth operational amplifier A4 are respectively connected to the other end of the second resistor R2 and the first end of the third resistor R3, the other end of the third resistor R3 One end of the first switch S1 is connected, and the other end of the first switch S1 is respectively connected to the inverting input end of the fifth operational amplifier A5, one end of the fifth resistor R5 and the sliding contact of the variable resistor R6, and the variable resistor R6 One end of the fourth resistor R4 is connected to one end of the fourth resistor R4, the other end of the fourth resistor R4 is connected to the second end of the second switch S2, the third end of the second switch S2 is grounded, and the other end of the fifth resistor R5 is connected to the fifth The output terminal of the operational amplifier A5, the output terminal of the fifth operational amplifier A5 outputs the second output signal Uout2.

其中第一开关S1是单刀单掷开关，第二开关S2是单刀双掷开关。Wherein the first switch S1 is a single pole single throw switch, and the second switch S2 is a single pole double throw switch.

其中基准电压产生装置提供的基准电压等于待测量的传感器的静态工作电压。Wherein the reference voltage provided by the reference voltage generating device is equal to the static working voltage of the sensor to be measured.

其中第一电阻、第二电阻、第三电阻和第五电阻之间的阻值关系为：Wherein the resistance relationship among the first resistor, the second resistor, the third resistor and the fifth resistor is:

$\frac{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>2</span>2</span>}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>1</span>1</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>3</span>3</span>}}<span><span>=</span>=</span>\frac{\mathrm{<span><span>1</span>1</span>}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>5</span>5</span>}}<span><span>,</span>,</span>$

其中R1表示第一电阻的阻值，R2表示第二电阻的阻值，R3表示第三电阻的阻值，R5表示第五电阻的阻值。Wherein R1 represents the resistance value of the first resistor, R2 represents the resistance value of the second resistor, R3 represents the resistance value of the third resistor, and R5 represents the resistance value of the fifth resistor.

可变电阻R6起到调节放大倍数的作用。The variable resistor R6 plays the role of adjusting the magnification.

上述输入信号Uin为待测量的传感器的输出电压。The above input signal Uin is the output voltage of the sensor to be measured.

第一和第二运算放大器用作为电压跟随器，其缓冲和隔离的作用。The first and second operational amplifiers act as voltage followers, which function as buffers and isolates.

下面简述本发明的针对小信号变化检测的电平转换电路的工作原理。The working principle of the level conversion circuit for small signal change detection of the present invention will be briefly described below.

本发明的针对小信号变化检测的电平转换电路就是要对输出电流信号的传感器的输出电压的变化量进行放大的电路。The level conversion circuit for small signal change detection of the present invention is a circuit for amplifying the change amount of the output voltage of the sensor outputting the current signal.

在测量前，要先设置好本发明的电路的静态工作点，以使得各个运算放大器的工作都处于不失真状态，并且还要设置好基准电压和放大倍数。常见的输出电流信号的传感器的输出电压Uin为：静态工作电压U0与随被测量变化的变化电压ΔV之和，即Uin＝U0±ΔV,并且静态工作电压U0为传感器的工作电压Vcc的一半，即V0＝1/2Vcc，因此将基准电压设置为等于待测量的传感器的静态工作电压U0，即传感器的工作电压Vcc的一半。又因为传感器输出的变化电压ΔV的变化较小，因此在实际使用时经常要对该变化电压ΔV进行放大，由此设置合适的放大倍数也是必要的。Before the measurement, the static operating point of the circuit of the present invention should be set, so that the operation of each operational amplifier is in an undistorted state, and the reference voltage and the amplification factor should also be set. The output voltage Uin of a common sensor that outputs a current signal is: the sum of the static operating voltage U0 and the variable voltage ΔV that changes with the measured value, that is, Uin=U0±ΔV, and the static operating voltage U0 is half of the operating voltage Vcc of the sensor. That is, V0=1/2Vcc, so the reference voltage is set to be equal to the static working voltage U0 of the sensor to be measured, that is, half of the working voltage Vcc of the sensor. And because the change of the change voltage ΔV output by the sensor is relatively small, it is often necessary to amplify the change voltage ΔV in actual use, so it is also necessary to set an appropriate magnification factor.

在测量传感器输出的变化电压ΔV之前，必须设置好该电路的放大倍数，可通过第一开关S1和第二开关S2的切换来计算得到。将第一开关S1断开，将第二开关S2接地。传感器不接入被测量的信号，此时传感器的输出电压为1/2Vcc，并且输入到第五运算放大器A5的同相输入端，第四电阻R4的一端接地，可变电阻R6的滑动触头连接第五运算放大器A5的反相输入端，由此可得此时的输出通过测量Uout2可以算得的值并且通过调节可变电阻R6的阻值来设置放大倍数，并得到期望的放大倍数。Before measuring the variable voltage ΔV output by the sensor, the amplification factor of the circuit must be set, which can be calculated by switching the first switch S1 and the second switch S2. The first switch S1 is turned off, and the second switch S2 is grounded. The sensor is not connected to the signal to be measured. At this time, the output voltage of the sensor is 1/2Vcc, and it is input to the non-inverting input terminal of the fifth operational amplifier A5, one end of the fourth resistor R4 is grounded, and the sliding contact of the variable resistor R6 is connected to The inverting input terminal of the fifth operational amplifier A5, thus the output at this time can be obtained By measuring Uout2 can be calculated The value and by adjusting the resistance of the variable resistor R6 to set the magnification, and get the desired magnification.

然后开始测量工作。将第一开关S1闭合，将第二开关S2闭合并连接至第二运算放大器A2的输出端，该第二运算放大器A2起电压跟随器的作用，其输出信号为基准电压U_REF。首先分析第四运算放大器A4的输出情况。该第四运算放大器A4的同相输入端接收输入信号Uin，通过第一电阻R1和负反馈回路上的第二电阻R2，根据深度负反馈放大电路的虚短和虚断的特点，可得：$\frac{Uin-U_{REF}}{R1}=\frac{UoutA4-Uin}{R2},$得到：Then start measuring. The first switch S1 is closed, the second switch S2 is closed and connected to the output terminal of the second operational amplifier A2, the second operational amplifier A2 acts as a voltage follower, and its output signal is the reference voltage U_REF . First, the output of the fourth operational amplifier A4 is analyzed. The non-inverting input terminal of the fourth operational amplifier A4 receives the input signal Uin, through the first resistor R1 and the second resistor R2 on the negative feedback loop, according to the characteristics of virtual short and virtual break of the deep negative feedback amplifier circuit, it can be obtained:$\frac{ui\mathrm{no}-u_{R\mathrm{E.}f}}{R1}=\frac{uoutA4-ui\mathrm{no}}{R2},$ get:

$\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>u</span>u</span>}\mathrm{<span><span>t</span>t</span>}\mathrm{<span><span>A</span>A</span>}\mathrm{<span><span>4</span>4</span>}<span><span>=</span>=</span>\frac{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>2</span>2</span>}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>1</span>1</span>}}<span><span>(</span>(</span>\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}<span><span>-</span>-</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>E</span>E.</span>}\mathrm{<span><span>F</span>f</span>}}<span><span>)</span>)</span><span><span>+</span>+</span>\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>1</span>1</span>}<span><span>)</span>)</span>$

其中R1表示第一电阻的阻值，R2表示第二电阻的阻值。Wherein R1 represents the resistance value of the first resistor, and R2 represents the resistance value of the second resistor.

第五运算放大器A5的同相输入端接收输入信号Uin，其反向输入端接收来自三路的输入信号：一路为通过第三电阻R3输入的UoutA4，一路为通过第四电阻R4和可变电阻R6输入的UoutA2，一路为通过第五电阻R5引入的负反馈信号Uout2。根据虚短和虚断的特点及基尔霍夫电流定律，列出第五运算放大器A5的反相输入端的电流方程，可得到：The noninverting input terminal of the fifth operational amplifier A5 receives the input signal Uin, and its inverting input terminal receives input signals from three channels: one is UoutA4 input through the third resistor R3, and the other is through the fourth resistor R4 and the variable resistor R6 One of the input UoutA2 is the negative feedback signal Uout2 introduced through the fifth resistor R5. According to the characteristics of virtual short and virtual break and Kirchhoff's current law, the current equation of the inverting input terminal of the fifth operational amplifier A5 is listed, and it can be obtained:

$\frac{\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>u</span>u</span>}\mathrm{<span><span>t</span>t</span>}\mathrm{<span><span>A</span>A</span>}\mathrm{<span><span>4</span>4</span>}<span><span>-</span>-</span>\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>3</span>3</span>}}<span><span>+</span>+</span>\frac{\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>u</span>u</span>}\mathrm{<span><span>t</span>t</span>}\mathrm{<span><span>2</span>2</span>}<span><span>-</span>-</span>\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>5</span>5</span>}}<span><span>=</span>=</span>\frac{\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}<span><span>-</span>-</span>{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>E</span>E.</span>}\mathrm{<span><span>F</span>f</span>}}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>4</span>4</span>}<span><span>+</span>+</span>\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>6</span>6</span>}}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>2</span>2</span>}<span><span>)</span>)</span>$

其中R3表示第三电阻的阻值，R4表示第四电阻的阻值，R5表示第五电阻的阻值，R6表示可变电阻的具体阻值。Wherein R3 represents the resistance value of the third resistor, R4 represents the resistance value of the fourth resistor, R5 represents the resistance value of the fifth resistor, and R6 represents the specific resistance value of the variable resistor.

结合公式(1)和(2)，化简，得到：Combining formulas (1) and (2) and simplifying, we get:

$\frac{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>2</span>2</span>}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>1</span>1</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>3</span>3</span>}}\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}<span><span>-</span>-</span>\frac{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>2</span>2</span>}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>1</span>1</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>3</span>3</span>}}{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>E</span>E.</span>}\mathrm{<span><span>F</span>f</span>}}<span><span>+</span>+</span>\frac{\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>u</span>u</span>}\mathrm{<span><span>t</span>t</span>}\mathrm{<span><span>2</span>2</span>}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>5</span>5</span>}}<span><span>-</span>-</span>\frac{\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>5</span>5</span>}}<span><span>=</span>=</span>\frac{\mathrm{<span><span>U</span>u</span>}\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}<span><span>-</span>-</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>E</span>E.</span>}\mathrm{<span><span>F</span>f</span>}}}{\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>4</span>4</span>}<span><span>+</span>+</span>\mathrm{<span><span>R</span>R</span>}\mathrm{<span><span>6</span>6</span>}}$

通过预先设计，使得$\frac{R2}{R1\&CenterDot;R3}=\frac{1}{R5},$可得：$\frac{Uout2-U_{REF}}{R5}=\frac{Uin-U_{REF}}{R4+R6},$即$\frac{Uout2-U_{REF}}{Uin-U_{REF}}=\frac{R5}{R4+R6},$因为的值已知，由此可得到的比值，这样可以直接得到传感器的输出电压Uin，继而得到放大的变化电压ΔV值。By pre-design, such that$\frac{R2}{R1\&Center\; Dot;R3}=\frac{1}{R5},$ Available:$\frac{uout2-u_{R\mathrm{E.}f}}{R5}=\frac{ui\mathrm{no}-u_{R\mathrm{E.}f}}{R4+R6},$ which is$\frac{uout2-u_{R\mathrm{E.}f}}{ui\mathrm{no}-u_{R\mathrm{E.}f}}=\frac{R5}{R4+R6},$ because The value of is known, so we can get In this way, the output voltage Uin of the sensor can be directly obtained, and then the amplified change voltage ΔV value can be obtained.

第三运算放大器A3用作比较器，其输出信号Uout1表示传感器的输出电压Uin的极性。A third operational amplifier A3 is used as a comparator whose output signal Uout1 indicates the polarity of the output voltage Uin of the sensor.

本发明所采用的各元器件的值可以根据具体的应用来确定，这里举例说明一组在实践中使用的元器件的值，第一电阻R1的阻值为10K欧姆，第二电阻R2的阻值为1K欧姆，第三电阻R3的阻值为10K欧姆，第四电阻R4的阻值为10K欧姆，第五电阻R5的阻值为100K欧姆，可变电阻R6的阻值范围为0-50K欧姆。The value of each component parts that the present invention adopts can be determined according to specific applications, and the value of a group of components and parts used in practice is illustrated here, the resistance value of the first resistance R1 is 10K ohm, the resistance value of the second resistance R2 The value is 1K ohms, the resistance value of the third resistor R3 is 10K ohms, the resistance value of the fourth resistor R4 is 10K ohms, the resistance value of the fifth resistor R5 is 100K ohms, and the resistance value range of the variable resistor R6 is 0-50K ohm.

通过本发明的针对小信号变化检测的电平转换电路既可以得到被测量的传感器的输出电压Uin的极性，又能够通过使用与待测量的传感器的静态输出电压相等的电压作为基准电压，并且设置合适的电阻值，实现对变化电压ΔV的放大，还可以调节和获知放大倍数，从而可以由测量值直接计算得到传感器的输出值Uin。该针对小信号变化检测的电平转换电路的测量误差小，方便实用。The polarity of the output voltage Uin of the sensor to be measured can be obtained through the level conversion circuit for small signal change detection of the present invention, and the voltage equal to the static output voltage of the sensor to be measured can be used as a reference voltage, and Set the appropriate resistance value to realize the amplification of the variable voltage ΔV, and also adjust and know the amplification factor, so that the output value Uin of the sensor can be directly calculated from the measured value. The level conversion circuit for small signal change detection has small measurement error, and is convenient and practical.

Claims (2)

1. for a level shifting circuit for small signal variation detection, comprising:

First operational amplifier, the second operational amplifier, the 3rd operational amplifier, the 4th operation amplifierDevice, the 5th operational amplifier, the first switch, second switch, the first resistance, the second resistance, the 3rdResistance, the 4th resistance, the 5th resistance, variable resistor and reference voltage generator, wherein firstThe normal phase input end of operational amplifier receives input signal, the inverting input of this first operational amplifierConnecting its output, the output of this first operational amplifier connects the anti-of the 3rd operational amplifier respectivelyPhase input, the normal phase input end of four-operational amplifier and the normal phase input end of the 5th operational amplifier,The normal phase input end of the 3rd operational amplifier connect respectively the second operational amplifier inverting input andOutput, the output of the 3rd operational amplifier exports the first output signal, this second operation amplifierThe normal phase input end of device connects reference voltage generator, and the output of this second operational amplifier also dividesNot connecting one end of the first resistance and the first end of second switch, the other end of this first resistance connects respectivelyConnect one end and the inverting input of four-operational amplifier of the second resistance, this four-operational amplifierOutput connects the other end and first end of the 3rd resistance of the second resistance respectively, the 3rd resistance anotherOne end connects one end of the first switch, and the other end of this first switch connects the 5th operational amplifier respectivelyInverting input, one end of the 5th resistance and variable-resistance slider, this is variable-resistance one years oldEnd connects one end of the 4th resistance, and the other end of the 4th resistance connects the second end of second switch, should3rd end ground connection of second switch, the other end of the 5th resistance connects the output of the 5th operational amplifierEnd, the output of the 5th operational amplifier exports the second output signal；

The reference voltage that wherein reference voltage generator provides is equal to the static work of sensor to be measuredMake voltage；

First resistance, the second resistance, value relatable between the 3rd resistance and the 5th resistance be:

$\frac{R2}{R1\&CenterDot;R3}=\frac{1}{R5},$

Wherein R1 represents the resistance of the first resistance, and R2 represents the resistance of the second resistance, and R3 represents the 3rdThe resistance of resistance, R5 represents the resistance of the 5th resistance.

Level shifting circuit for small signal variation detection the most according to claim 1, whereinFirst switch is single-pole single-throw switch (SPST), and second switch is single-pole double-throw switch (SPDT).