WO2016074261A1 - 一种运算放大器的自调零电路 - Google Patents

一种运算放大器的自调零电路 Download PDF

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Publication number
WO2016074261A1
WO2016074261A1 PCT/CN2014/091467 CN2014091467W WO2016074261A1 WO 2016074261 A1 WO2016074261 A1 WO 2016074261A1 CN 2014091467 W CN2014091467 W CN 2014091467W WO 2016074261 A1 WO2016074261 A1 WO 2016074261A1
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Prior art keywords
operational amplifier
offset voltage
threshold
self
signal
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PCT/CN2014/091467
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English (en)
French (fr)
Inventor
何健
许神贤
包玉刚
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TCL China Star Optoelectronics Technology Co Ltd
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Shenzhen China Star Optoelectronics Technology Co Ltd
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Priority to US14/416,047 priority Critical patent/US9455673B2/en
Publication of WO2016074261A1 publication Critical patent/WO2016074261A1/zh
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H03F3/45479—Differential amplifiers with semiconductor devices only characterised by the way of common mode signal rejection
    • H03F3/45928—Differential amplifiers with semiconductor devices only characterised by the way of common mode signal rejection using IC blocks as the active amplifying circuit
    • H03F3/45968—Differential amplifiers with semiconductor devices only characterised by the way of common mode signal rejection using IC blocks as the active amplifying circuit by offset reduction
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
    • H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit

Definitions

  • the present invention relates to operational amplifier calibration techniques, and more particularly to a self-zeroing circuit for an operational amplifier.
  • the application of the operational amplifier is very extensive. During the operation of the operational amplifier, due to its working principle and the influence of the environment, voltage drift will occur, resulting in an offset voltage output when there is no input voltage, which directly affects the measurement sensitivity of the entire system. In order to improve the voltage offset of the operational amplifier, the operational amplifier often has a zero adjustment terminal, and the offset voltage can be adjusted by a manual zero adjustment circuit.
  • Vi is the input voltage
  • Vo is the output voltage
  • the two power terminals +VCC and -VEE are adjusted by the variable resistor R.
  • the current at the terminal thereby reducing the offset voltage of the output of the operational amplifier.
  • the manual zero adjustment operation process is cumbersome, the adjustment time is long, and the precision is difficult to ensure; at the same time, the operational amplifier circuit is often built in the fixture, which makes the manual zero adjustment operation have limitations.
  • Embodiments of the present invention provide a self-zeroing circuit of an operational amplifier, including:
  • An operational amplifier comprising: an input end, an output end, and a zero adjustment end, wherein the input end is configured to receive an input signal; the output end is configured to generate an output signal and the zero adjustment end for processing the input signal, and Performing a zero adjustment operation on the operational amplifier;
  • An analog to digital converter for converting the output signal to a digital signal
  • a micro control unit configured to acquire a voltage value of the offset voltage of the output terminal according to the digital signal when the input terminal has no input signal, and compare the amplitude of the offset voltage with the first threshold to generate Comparing the result, generating a control signal according to the comparison result, wherein the control signal is used to make the voltage value of the offset voltage less than a first threshold;
  • a digital potentiometer for adjusting its own resistance according to the regulation signal to zero the operational amplifier
  • the temperature sensing module is used to detect the current ambient temperature and record the initial temperature after the last zeroing operation is completed.
  • the micro control unit is further configured to generate a control signal when the comparison result is that the amplitude of the offset voltage is greater than the first threshold.
  • the digital potentiometer includes a first digital potentiometer and a second digital potentiometer, the first digital potentiometer for substantially adjusting the resistance; Two digital potentiometers for small adjustment of the resistance.
  • the micro control unit is further configured to: when the amplitude of the offset voltage is greater than a second threshold, adjust a resistance of the first digital potentiometer to Making the magnitude of the offset voltage less than or equal to the second threshold;
  • the micro control unit is further configured to generate a prompt signal according to the current ambient temperature and the initial temperature to trigger a zero adjustment operation on the operational amplifier.
  • the micro control unit is further configured to obtain, according to the current ambient temperature, a voltage value of a current offset voltage of the output end corresponding to the current ambient temperature. And obtaining, according to the initial temperature, a voltage value of an initial offset voltage of the output end corresponding to the initial temperature; and generating a prompt signal according to the voltage value of the current offset voltage and the voltage value of the initial offset voltage, Triggering the zero operation of the operational amplifier.
  • the micro control unit is further configured to determine whether a difference between a voltage value of the current offset voltage and a voltage value of the initial offset voltage is greater than a third threshold, and generate critical result.
  • the micro control unit is further configured to: when the determining result is that the difference between the voltage value of the current offset voltage and the voltage value of the initial offset voltage is greater than When the third threshold is described, a zeroing operation is performed on the operational amplifier.
  • Embodiments of the present invention provide a self-zeroing circuit of an operational amplifier, including:
  • An operational amplifier comprising: an input end, an output end, and a zero adjustment end, wherein the input end is configured to receive an input signal; the output end is configured to generate an output signal and the zero adjustment end for processing the input signal, and Performing a zero adjustment operation on the operational amplifier;
  • An analog to digital converter for converting the output signal to a digital signal
  • a micro control unit configured to: when the input end has no input signal, acquire a voltage value of the offset voltage of the output terminal according to the digital signal, and generate a control signal according to the voltage value of the offset voltage, wherein the control signal Used to cause the voltage value of the offset voltage to be less than a first threshold;
  • a digital potentiometer for adjusting its own resistance according to the regulation signal to zero the operational amplifier.
  • the micro control unit is further configured to compare the amplitude of the offset voltage with the first threshold, generate a comparison result, and generate a control signal according to the comparison result.
  • the micro control unit is further configured to generate a control signal when the comparison result is that the amplitude of the offset voltage is greater than the first threshold.
  • the digital potentiometer includes a first digital potentiometer and a second digital potentiometer, the first digital potentiometer for substantially adjusting the resistance; Two digital potentiometers for small adjustment of the resistance.
  • the micro control unit is further configured to: when the amplitude of the offset voltage is greater than a second threshold, adjust a resistance of the first digital potentiometer to Making the magnitude of the offset voltage less than or equal to the second threshold;
  • the self-zeroing circuit further includes a temperature sensing module, the temperature sensing module is configured to detect a current ambient temperature, and record an initial after the last zeroing operation is completed. temperature.
  • the micro control unit is further configured to generate a prompt signal according to the current ambient temperature and the initial temperature to trigger a zero adjustment operation on the operational amplifier.
  • the micro control unit is further configured to obtain, according to the current ambient temperature, a voltage value of a current offset voltage of the output end corresponding to the current ambient temperature. And obtaining, according to the initial temperature, a voltage value of an initial offset voltage of the output end corresponding to the initial temperature; and generating a prompt signal according to the voltage value of the current offset voltage and the voltage value of the initial offset voltage, Triggering the zero operation of the operational amplifier.
  • the micro control unit is further configured to determine whether a difference between a voltage value of the current offset voltage and a voltage value of the initial offset voltage is greater than a third threshold, and generate critical result.
  • the micro control unit is further configured to: when the determining result is that the difference between the voltage value of the current offset voltage and the voltage value of the initial offset voltage is greater than When the third threshold is described, a zeroing operation is performed on the operational amplifier.
  • the self-tuning zero circuit of the operational amplifier of the invention solves the problem of inaccurate zero adjustment of the existing operational amplifier by designing an improved self-zeroing circuit, thereby improving the sensitivity of the measurement.
  • 1 is a schematic structural view of a zeroing circuit of a conventional operational amplifier
  • FIG. 2 is a schematic structural diagram of a self-zeroing circuit of an operational amplifier according to a first embodiment of the present invention
  • FIG. 3 is a schematic structural diagram of a self-zeroing circuit of an operational amplifier according to a second embodiment of the present invention.
  • FIG. 4 is a schematic structural diagram of a self-zeroing circuit of an operational amplifier according to a third embodiment of the present invention.
  • Fig. 5 is a temperature-offset voltage curve in the third embodiment of the present invention.
  • FIG. 2 is a schematic structural diagram of a self-zeroing circuit of an operational amplifier according to a first embodiment of the present invention.
  • the self-zeroing circuit of the operational amplifier of the present invention comprises: an operational amplifier 101, an analog to digital converter 102, a micro control unit 103, a digital potentiometer 104, wherein the operational amplifier 101 includes an input terminal, an output terminal, and a zeroing terminal.
  • the zero terminal is two and the two power terminals are respectively +VCC and -VEE; the input terminal receives an input signal Vi, and the output terminal processes the input signal to generate an output signal Vo; Performing a zeroing operation on the operational amplifier 101; one end of the analog-to-digital converter 102 is connected to an output end of the operational amplifier 101, and the other end thereof is connected to one end of the micro control unit 103; The other end is connected to the digital potentiometer 104; the digital potentiometer 104 is connected to the zeroing terminal.
  • the digital potentiometer 104 is also coupled to the power supply terminal -VEE, which provides power to the digital potentiometer 104.
  • the output signal of the operational amplifier 101 is generally an analog signal, it is necessary to convert the output signal of the operational amplifier 101 into a digital signal by the analog-to-digital converter 102 to implement analog-to-digital conversion.
  • the input end of the operational amplifier is first turned off, so that the input terminal has no input signal, and the micro control unit 103 is converted according to the analog-to-digital converter 102.
  • the digital signal, the voltage value of the offset voltage of the output terminal is obtained, and a control signal is generated according to the voltage value of the offset voltage, wherein the control signal is used to make the voltage value of the offset voltage less than a first threshold.
  • the first threshold may be set according to an actual measurement accuracy requirement, and the first threshold is a value close to zero.
  • the resistance of the digital potentiometer 104 is adjusted by the regulation signal generated by the micro control unit 103, thereby zeroing the operational amplifier 101.
  • the voltage value of the offset voltage satisfies the requirement, and the zero adjustment of the operational amplifier is realized.
  • the self-tuning zero circuit of the operational amplifier of the invention solves the problem of inaccurate zero adjustment of the existing operational amplifier by designing an improved self-zeroing circuit, thereby improving the sensitivity of the measurement.
  • FIG. 3 is a schematic structural diagram of a self-zeroing circuit of an operational amplifier according to a second embodiment of the present invention.
  • the self-zeroing circuit of the operational amplifier of the present invention includes: an operational amplifier 201, an analog-to-digital converter 202, a micro control unit 203, a digital potentiometer 204, wherein the operational amplifier 201 includes an input terminal, an output terminal, and a modulation Zero terminal, two power terminals are +VCC and -VEE; the input terminal receives an input signal Vi; the output terminal processes an output signal Vo for the input signal processing; the zeroing terminal is opposite to the operational amplifier 201 performing a zero adjustment operation; one end of the analog-to-digital converter 202 is connected to an output end of the operational amplifier 201, and the other end thereof is connected to one end of the micro control unit 203; the other end of the micro control unit 203 is The digital potentiometer 204 is connected; the digital potentiometer 204 is connected to the zero adjustment terminal; the digital potentiometer 204 is also connected to the power supply terminal -VEE, and the power supply terminal -VEE is connected to the digital potentiometer
  • the zeroing terminal is two, the digital potentiometer 204 can include a first digital potentiometer 205 and a second digital potentiometer 206, the first digital potentiometer 205 can greatly adjust the resistance, the second The digital potentiometer 206 can adjust the resistance to a small extent, the first digital potentiometer 205 is coupled to one of the zeroing terminals; the second digital potentiometer 206 is coupled to another one of the zeroing terminals.
  • the output signal of the operational amplifier 201 is generally an analog signal, it is necessary to convert the output signal of the operational amplifier 201 into a digital signal by the analog-to-digital converter 202 to implement analog-to-digital conversion.
  • the input end of the operational amplifier is first turned off, so that the input terminal has no input signal, and the micro control unit 203 is converted according to the analog-to-digital converter 202.
  • the digital signal acquires a voltage value of the offset voltage of the output end, and the micro control unit 203 compares the acquired amplitude of the offset voltage with a first threshold to generate a comparison result, when the comparison result is Generating a control signal when the amplitude of the offset voltage is greater than the first threshold, wherein the control signal is used to make a voltage value of the offset voltage less than the first threshold;
  • the first threshold may be based on actual measurement accuracy
  • the demand is set, and the first threshold is close to zero.
  • the resistance of the digital potentiometer 204 is adjusted by the control signal generated by the micro control unit 203, thereby zeroing the operational amplifier 201. Through the regulation of the micro control unit 203, the voltage value of the offset voltage satisfies the demand.
  • a second threshold may also be set, the second threshold being much larger than the first threshold.
  • the micro control unit 203 substantially adjusts the resistance of the digital potentiometer, that is, adjusts the resistance of the first digital potentiometer 205, when adjusted to When the amplitude of the offset voltage is less than or equal to the second threshold, the large-scale adjustment is stopped;
  • the micro control unit 203 When the amplitude of the offset voltage is less than or equal to the second threshold, the micro control unit 203 performs small-scale adjustment of the resistance of the digital potentiometer, that is, the resistance adjustment of the second digital potentiometer 206. And when the amplitude of the offset voltage is less than or equal to the first threshold, the adjustment is stopped.
  • the self-tuning zero circuit of the operational amplifier of the invention solves the problem of inaccurate zero adjustment of the existing operational amplifier by designing an improved self-zeroing circuit, thereby improving the sensitivity of the measurement.
  • FIG. 4 is a schematic structural diagram of a self-zeroing circuit of an operational amplifier according to a third embodiment of the present invention.
  • the self-zeroing circuit of the operational amplifier of the embodiment may further include a temperature sensing module 105. Since the temperature is critical to the offset voltage of the operational amplifier, in order to maintain the offset voltage at a low level for a long time, it is necessary to provide the temperature sensing module 105.
  • the temperature sensing module 105 detects the current ambient temperature and records the initial temperature after the last zero adjustment operation is completed.
  • the micro control unit 104 obtains, according to the current ambient temperature detected by the temperature sensing module 105, a voltage value of a current offset voltage of the output end corresponding to the current ambient temperature; and according to the initial At a temperature, a voltage value of an initial offset voltage of the output terminal corresponding to the initial temperature is obtained.
  • the voltage value of the current offset voltage of the output end corresponding to the current ambient temperature can be obtained by a temperature-offset voltage curve, as shown in FIG. 5, and the abscissa represents the temperature T, the ordinate Indicates the offset voltage VOS.
  • the voltage value of the initial offset voltage of the output terminal corresponding to the initial temperature can also be obtained by the temperature-offset voltage curve.
  • the micro control unit 104 determines whether the difference between the voltage value of the current offset voltage and the voltage value of the initial offset voltage is greater than a third threshold, and generates a determination result.
  • the third threshold may be set according to the demand of the actual measurement accuracy.
  • the temperature sensing module 105 Since the temperature sensing module 105 detects the change of the ambient temperature in real time, thereby avoiding the temperature change being excessively large, the offset voltage may exceed the first threshold again, and the prompt information sent by the temperature sensing module 105 is applied to the operational amplifier. The zeroing operation is performed again, so that the offset voltage is maintained at a low level for a long time.
  • the technical solution of the embodiment is also applicable to the second embodiment.
  • the self-regulating circuit of the operational amplifier of the present invention avoids the influence of temperature on the offset voltage by increasing the temperature sensing module, so that the offset voltage is maintained at a low level for a long time.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
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Abstract

本发明提供一种运算放大器的自调零电路，所述自调零电路包括：微控制单元、数字电位器；所述微控制单元，用于在运算放大器无输入时，获取所述运算放大器输出端的失调电压的电压值，并根据所述失调电压的电压值生成使所述失调电压的电压值小于第一阈值的调控信号；所述数字电位器，用于根据所述调控信号调节自身的电阻。

Description

一种运算放大器的自调零电路 技术领域
本发明涉及运算放大器校准技术，特别是涉及一种运算放大器的自调零电路。
 背景技术
运算放大器的应用十分广泛，在运算放大器的使用过程中，由于其工作原理及受环境的影响，会产生电压漂移，造成无输入电压时也会有失调电压输出，直接影响整个系统的测量灵敏度。为改善运算放大器的电压失调问题，运算放大器常设有调零端，可通过手工调零电路调节失调电压。
目前，现有的运算放大器的调零电路的结构示意图如图1所示，Vi为输入电压，Vo为输出电压，两个电源接线端+VCC和-VEE，通过可变电阻R调节两调零端的电流，从而减小运算放大器的输出的失调电压。但是，手工调零操作过程比较繁琐，调节时间较长，精度很难保证；同时运算放大器电路常常内置在治具中，使得手工调零操作存在局限性。
故，有必要提供一种运算放大器的自调零电路，以解决现有技术所存在的问题。
 技术问题
本发明的目的在于提供一种运算放大器的自调零电路，以解决现有运算放大器调零不精确的问题，从而提高测量的灵敏度。
 技术解决方案
本发明实施例提供一种运算放大器的自调零电路，其包括：
运算放大器，包括输入端，输出端，调零端，所述输入端，用于接收输入信号；所述输出端，用于对所述输入信号处理产生输出信号及所述调零端，用于对所述运算放大器进行调零操作；
模数转换器，用于将所述输出信号转换数字信号；
微控制单元，用于在所述输入端无输入信号时，根据所述数字信号获取所述输出端的失调电压的电压值，并将所述失调电压的幅值和所述第一阈值比较，生成比较结果，根据所述比较结果生成调控信号，其中所述调控信号用于使所述失调电压的电压值小于第一阈值；
数字电位器，用于根据所述调控信号调节自身的电阻，以对所述运算放大器进行调零；以及
温度感应模块，用于检测当前的环境温度，并记录上一次调零操作完成后的初始温度。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于当所述比较结果为所述失调电压的幅值大于所述第一阈值时，生成调控信号。
在本发明的运算放大器的自调零电路中，所述数字电位器包括第一数字电位器和第二数字电位器，所述第一数字电位器，用于大幅度地调节电阻；所述第二数字电位器，用于小幅度地调节电阻。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于当所述失调电压的幅值大于第二阈值时，对所述第一数字电位器的电阻进行调节，以使所述失调电压的幅值小于等于所述第二阈值；
当所述失调电压的幅值小于或等于所述第二阈值时，对所述第二数字电位器的电阻进行调节，以使所述失调电压的幅值小于等于所述第一阈值，其中所述第二阈值大于所述第一阈值。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于根据所述当前的环境温度与所述初始温度生成提示信号，以触发对所述运算放大器进行调零操作。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于根据所述当前的环境温度，获得与所述当前的环境温度对应的所述输出端的当前失调电压的电压值；并根据所述初始温度，获得与所述初始温度对应的所述输出端的初始失调电压的电压值；以及根据所述当前失调电压的电压值和所述初始失调电压的电压值生成提示信号，以触发对所述运算放大器进行调零操作。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于判断所述当前失调电压的电压值与所述初始失调电压的电压值的差值是否大于第三阈值，生成判断结果。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于当所述判断结果为所述当前失调电压的电压值与所述初始失调电压的电压值的差值大于所述第三阈值时，触发对所述运算放大器进行调零操作。
本发明实施例提供一种运算放大器的自调零电路，其包括：
运算放大器，包括输入端，输出端，调零端，所述输入端，用于接收输入信号；所述输出端，用于对所述输入信号处理产生输出信号及所述调零端，用于对所述运算放大器进行调零操作；
模数转换器，用于将所述输出信号转换数字信号；
微控制单元，用于在所述输入端无输入信号时，根据所述数字信号获取所述输出端的失调电压的电压值，并根据所述失调电压的电压值生成调控信号，其中所述调控信号用于使所述失调电压的电压值小于第一阈值；以及
数字电位器，用于根据所述调控信号调节自身的电阻，以对所述运算放大器进行调零。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于将所述失调电压的幅值和所述第一阈值比较，生成比较结果，根据所述比较结果生成调控信号。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于当所述比较结果为所述失调电压的幅值大于所述第一阈值时，生成调控信号。
在本发明的运算放大器的自调零电路中，所述数字电位器包括第一数字电位器和第二数字电位器，所述第一数字电位器，用于大幅度地调节电阻；所述第二数字电位器，用于小幅度地调节电阻。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于当所述失调电压的幅值大于第二阈值时，对所述第一数字电位器的电阻进行调节，以使所述失调电压的幅值小于等于所述第二阈值；
当所述失调电压的幅值小于或等于所述第二阈值时，对所述第二数字电位器的电阻进行调节，以使所述失调电压的幅值小于等于所述第一阈值，其中所述第二阈值大于所述第一阈值。
在本发明的运算放大器的自调零电路中，所述自调零电路还包括温度感应模块，所述温度感应模块，用于检测当前的环境温度，并记录上一次调零操作完成后的初始温度。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于根据所述当前的环境温度与所述初始温度生成提示信号，以触发对所述运算放大器进行调零操作。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于根据所述当前的环境温度，获得与所述当前的环境温度对应的所述输出端的当前失调电压的电压值；并根据所述初始温度，获得与所述初始温度对应的所述输出端的初始失调电压的电压值；以及根据所述当前失调电压的电压值和所述初始失调电压的电压值生成提示信号，以触发对所述运算放大器进行调零操作。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于判断所述当前失调电压的电压值与所述初始失调电压的电压值的差值是否大于第三阈值，生成判断结果。
在本发明的运算放大器的自调零电路中，所述微控制单元，还用于当所述判断结果为所述当前失调电压的电压值与所述初始失调电压的电压值的差值大于所述第三阈值时，触发对所述运算放大器进行调零操作。
 有益效果
本发明的运算放大器的自调零电路，通过设计一种改进的自调零电路，解决了现有运算放大器调零不精确的问题，从而提高测量的灵敏度。
 附图说明
图1为现有的运算放大器的调零电路的结构示意图；
图2为本发明第一实施例的运算放大器的自调零电路的结构示意图；
图3为本发明第二实施例的运算放大器的自调零电路的结构示意图；
图4为本发明第三实施例的运算放大器的自调零电路的结构示意图；
图5为本发明第三实施例中的温度-失调电压曲线。
 本发明的最佳实施方式
以下各实施例的说明是参考附加的图式，用以例示本发明可用以实施的特定实施例。本发明所提到的方向用语，例如「上」、「下」、「前」、「后」、「左」、「右」、「内」、「外」、「侧面」等，仅是参考附加图式的方向。因此，使用的方向用语是用以说明及理解本发明，而非用以限制本发明。
在图中，结构相似的单元是以相同标号表示。
请参照图2，图2为本发明第一实施例的运算放大器的自调零电路的结构示意图。
本发明的运算放大器的自调零电路，包括：运算放大器101，模数转换器102，微控制单元103，数字电位器104，其中运算放大器101，包括输入端，输出端，调零端，所述调零端为两个以及两个电源接线端分别为+VCC和-VEE；所述输入端接收输入信号Vi，所述输出端对所述输入信号处理产生输出信号Vo；所述调零端对所述运算放大器101进行调零操作；所述模数转换器102的一端连接所述运算放大器101的输出端，其另一端连接所述微控制单元103的一端；所述微控制单元103的另一端与所述数字电位器104连接；所述数字电位器104连接所述调零端。所述数字电位器104还与所述电源接线端-VEE连接，所述电源接线端-VEE向所述数字电位器104提供电源。
由于所述运算放大器101的输出信号一般是模拟信号，因此需要通过所述模数转换器102将所述运算放大器101的所述输出信号转换数字信号，实现模数转化。
在所述运算放大器的自调零电路工作时，先关闭所述运算放大器的输入端，使得所述输入端无输入信号，此时所述微控制单元103根据所述模数转换器102转换得到的所述数字信号，获取所述输出端的失调电压的电压值，并根据所述失调电压的电压值生成调控信号，其中所述调控信号用于使所述失调电压的电压值小于第一阈值，所述第一阈值可根据实际的测量精度的需求设定，所述第一阈值为接近零的值。
通过所述微控制单元103产生的调控信号，对所述数字电位器104的电阻进行调节，从而对所述运算放大器101进行调零。经过所述微控制单元103的调控，使所述失调电压的电压值满足需求，实现了对运算放大器的调零。
本发明的运算放大器的自调零电路，通过设计一种改进的自调零电路，解决了现有运算放大器调零不精确的问题，从而提高测量的灵敏度。
请参照图3，图3为本发明第二实施例的运算放大器的自调零电路的结构示意图。
结合图3，本发明的运算放大器的自调零电路，包括：运算放大器201，模数转换器202，微控制单元203，数字电位器204，其中运算放大器201，包括输入端，输出端，调零端，两个电源接线端分别为+VCC和-VEE；所述输入端接收输入信号Vi；所述输出端对所述输入信号处理产生输出信号Vo；所述调零端对所述运算放大器201进行调零操作；所述模数转换器202的一端连接所述运算放大器201的输出端，其另一端连接所述微控制单元203的一端；所述微控制单元203的另一端与所述数字电位器204连接；所述数字电位器204连接所述调零端；所述数字电位器204还与所述电源接线端-VEE连接，所述电源接线端-VEE向所述数字电位器204提供电源。
所述调零端为两个，所述数字电位器204可包括第一数字电位器205和第二数字电位器206，所述第一数字电位器205可以大幅度地调节电阻，所述第二数字电位器206可以小幅度地调节电阻，所述第一数字电位器205与其中一个所述调零端连接；所述第二数字电位器206与另外一个所述调零端连接。
由于所述运算放大器201的输出信号一般是模拟信号，因此需要通过所述模数转换器202将所述运算放大器201的所述输出信号转换数字信号，实现模数转化。
在所述运算放大器的自调零电路工作时，先关闭所述运算放大器的输入端，使得所述输入端无输入信号，此时所述微控制单元203根据所述模数转换器202转换得到的所述数字信号获取所述输出端的失调电压的电压值，所述微控制单元203将获取到的所述失调电压的幅值和第一阈值比较，生成比较结果，当所述比较结果为所述失调电压的幅值大于所述第一阈值时，生成调控信号，其中所述调控信号用于使所述失调电压的电压值小于所述第一阈值；所述第一阈值可根据实际测量精度的需求设定，第一阈值接近零的值。
当所述比较结果为所述失调电压的幅值小于等于所述第一阈值时，不生成调控信号，即不对所述运算放大器进行调零操作。
通过所述微控制单元203产生的调控信号，对所述数字电位器204的电阻进行调节，从而对所述运算放大器201进行调零。经过所述微控制单元203的调控，使所述失调电压的电压值满足需求。
为了达到更好的调零效果，还可设置第二阈值，所述第二阈值远大于所述第一阈值。当所述失调电压的幅值大于第二阈值时，所述微控制单元203对所述数字电位器的电阻进行大幅度调节，即对所述第一数字电位器205的电阻调节，当调节到所述失调电压的幅值小于等于所述第二阈值时，停止大幅度调节；
当所述失调电压的幅值小于或等于所述第二阈值时，所述微控制单元203对所述数字电位器的电阻进行小幅度调节，即对所述第二数字电位器206的电阻调节，当所述失调电压的幅值小于等于所述第一阈值，停止调节。
本发明的运算放大器的自调零电路，通过设计一种改进的自调零电路，解决了现有运算放大器调零不精确的问题，从而提高测量的灵敏度。
请参照图4，图4为本发明第三实施例的运算放大器的自调零电路的结构示意图。
本实施例和第一实例的区别在于：本实施例的所述运算放大器的自调零电路还可包括温度感应模块105。由于温度对所述运算放大器的失调电压影响非常关键，为了使所述失调电压长时间维持在较低水平，因此有必要设置所述温度感应模块105。
当每次调零操作结束后，所述温度感应模块105检测当前的环境温度，并记录上一次调零操作完成后的初始温度。
所述微控制单元104，根据所述温度感应模块105检测到的所述当前的环境温度，获得与所述当前的环境温度对应的所述输出端的当前失调电压的电压值；并根据所述初始温度，获得与所述初始温度对应的所述输出端的初始失调电压的电压值。与所述当前的环境温度对应的所述输出端的当前失调电压的电压值可通过温度-失调电压曲线得到，所述温度-失调电压曲线如图5所示，其横坐标表示温度T，纵坐标表示失调电压VOS。与所述初始温度对应的所述输出端的初始失调电压的电压值，也可通过所述温度-失调电压曲线得到。
进一步所述微控制单元104，判断所述当前失调电压的电压值与所述初始失调电压的电压值的差值是否大于第三阈值，生成判断结果。所述第三阈值可根据实际测量精度的需求设定。当所述微控制单元104的判断结果为所述当前失调电压的电压值与所述初始失调电压的电压值的差值大于所述第三阈值时，生成提示信号，譬如报警，以触发对所述运算放大器进行调零操作。当所述微控制单元的判断结果为所述当前失调电压的电压值与所述初始失调电压的电压值的差值小于或等于所述第三阈值时，不生成提示信号，不触发对所述运算放大器进行调零操作。
由于通过所述温度感应模块105实时检测环境温度的变化，从而避免温度变化过大时，所述失调电压会再次超出所述第一阈值，通过温度感应模块105发出的提示信息对所述运算放大器再次进行调零操作，从而使所述失调电压长时间维持在较低水平。本实施例的技术方案同样适用于第二实施例。
本发明的运算放大器的自调零电路，通过增加温度感应模块，避免温度对失调电压的影响，使失调电压长时间维持在较低水平。
综上所述，虽然本发明已以优选实施例揭露如上，但上述优选实施例并非用以限制本发明，本领域的普通技术人员，在不脱离本发明的精神和范围内，均可作各种更动与润饰，因此本发明的保护范围以权利要求界定的范围为准。

Claims (18)

  1. 一种运算放大器的自调零电路，其包括：
    运算放大器，包括输入端，输出端，调零端，所述输入端，用于接收输入信号；所述输出端，用于对所述输入信号处理产生输出信号及所述调零端，用于对所述运算放大器进行调零操作；
    模数转换器，用于将所述输出信号转换数字信号；
    微控制单元，用于在所述输入端无输入信号时，根据所述数字信号获取所述输出端的失调电压的电压值，并将所述失调电压的幅值和所述第一阈值比较，生成比较结果，根据所述比较结果生成调控信号，其中所述调控信号用于使所述失调电压的电压值小于第一阈值；
    数字电位器，用于根据所述调控信号调节自身的电阻，以对所述运算放大器进行调零；以及
    温度感应模块，用于检测当前的环境温度，并记录上一次调零操作完成后的初始温度。
  2. 根据权利要求1所述的运算放大器的自调零电路，其中所述微控制单元，还用于当所述比较结果为所述失调电压的幅值大于所述第一阈值时，生成调控信号。
  3. 根据权利要求1所述的运算放大器的自调零电路，其中所述数字电位器包括第一数字电位器和第二数字电位器，所述第一数字电位器，用于大幅度地调节电阻；所述第二数字电位器，用于小幅度地调节电阻。
  4. 根据权利要求3所述的运算放大器的自调零电路，其中所述微控制单元，还用于当所述失调电压的幅值大于第二阈值时，对所述第一数字电位器的电阻进行调节，以使所述失调电压的幅值小于等于所述第二阈值；
    当所述失调电压的幅值小于或等于所述第二阈值时，对所述第二数字电位器的电阻进行调节，以使所述失调电压的幅值小于等于所述第一阈值，其中所述第二阈值大于所述第一阈值。
  5. 根据权利要求1所述的运算放大器的自调零电路，其中所述微控制单元，还用于根据所述当前的环境温度与所述初始温度生成提示信号，以触发对所述运算放大器进行调零操作。
  6. 根据权利要求5所述的运算放大器的自调零电路，其中所述微控制单元，还用于根据所述当前的环境温度，获得与所述当前的环境温度对应的所述输出端的当前失调电压的电压值；并根据所述初始温度，获得与所述初始温度对应的所述输出端的初始失调电压的电压值；以及根据所述当前失调电压的电压值和所述初始失调电压的电压值生成提示信号，以触发对所述运算放大器进行调零操作。
  7. 根据权利要求6所述的运算放大器的自调零电路，其中所述微控制单元，还用于判断所述当前失调电压的电压值与所述初始失调电压的电压值的差值是否大于第三阈值，生成判断结果。
  8. 根据权利要求7所述的运算放大器的自调零电路，其中所述微控制单元，还用于当所述判断结果为所述当前失调电压的电压值与所述初始失调电压的电压值的差值大于所述第三阈值时，触发对所述运算放大器进行调零操作。
  9. 一种运算放大器的自调零电路，其包括：
    运算放大器，包括输入端，输出端，调零端，所述输入端，用于接收输入信号；所述输出端，用于对所述输入信号处理产生输出信号及所述调零端，用于对所述运算放大器进行调零操作；
    模数转换器，用于将所述输出信号转换数字信号；
    微控制单元，用于在所述输入端无输入信号时，根据所述数字信号获取所述输出端的失调电压的电压值，并根据所述失调电压的电压值生成调控信号，其中所述调控信号用于使所述失调电压的电压值小于第一阈值；以及
    数字电位器，用于根据所述调控信号调节自身的电阻，以对所述运算放大器进行调零。
  10. 根据权利要求9所述的运算放大器的自调零电路，其中所述微控制单元，还用于将所述失调电压的幅值和所述第一阈值比较，生成比较结果，根据所述比较结果生成调控信号。
  11. 根据权利要求10所述的运算放大器的自调零电路，其中所述微控制单元，还用于当所述比较结果为所述失调电压的幅值大于所述第一阈值时，生成调控信号。
  12. 根据权利要求9所述的运算放大器的自调零电路，其中所述数字电位器包括第一数字电位器和第二数字电位器，所述第一数字电位器，用于大幅度地调节电阻；所述第二数字电位器，用于小幅度地调节电阻。
  13. 根据权利要求12所述的运算放大器的自调零电路，其中所述微控制单元，还用于当所述失调电压的幅值大于第二阈值时，对所述第一数字电位器的电阻进行调节，以使所述失调电压的幅值小于等于所述第二阈值；
    当所述失调电压的幅值小于或等于所述第二阈值时，对所述第二数字电位器的电阻进行调节，以使所述失调电压的幅值小于等于所述第一阈值，其中所述第二阈值大于所述第一阈值。
  14. 根据权利要求9所述的运算放大器的自调零电路，其中所述自调零电路还包括温度感应模块，所述温度感应模块，用于检测当前的环境温度，并记录上一次调零操作完成后的初始温度。
  15. 根据权利要求14所述的运算放大器的自调零电路，其中所述微控制单元，还用于根据所述当前的环境温度与所述初始温度生成提示信号，以触发对所述运算放大器进行调零操作。
  16. 根据权利要求15所述的运算放大器的自调零电路，其中所述微控制单元，还用于根据所述当前的环境温度，获得与所述当前的环境温度对应的所述输出端的当前失调电压的电压值；并根据所述初始温度，获得与所述初始温度对应的所述输出端的初始失调电压的电压值；以及根据所述当前失调电压的电压值和所述初始失调电压的电压值生成提示信号，以触发对所述运算放大器进行调零操作。
  17. 根据权利要求16所述的运算放大器的自调零电路，其中所述微控制单元，还用于判断所述当前失调电压的电压值与所述初始失调电压的电压值的差值是否大于第三阈值，生成判断结果。
  18. 根据权利要求17所述的运算放大器的自调零电路，其中所述微控制单元，还用于当所述判断结果为所述当前失调电压的电压值与所述初始失调电压的电压值的差值大于所述第三阈值时，触发对所述运算放大器进行调零操作。
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