用放大器反馈控制消除电桥非线性误差

Cancellation of nonlinear error of bridge using op amp feedback control

采用放大器反馈控制法克服了传感器电桥的非线性误差,通过解析的方法找到了克服非线性误差的放大器反馈控制条件。在忽略放大器输入偏置电流和输入噪声电压的情况下,给出了四种校正电路中放大器失调电压对测量系统影响的输出表达式,并分析比较了每一种校正方法的特点,得到最佳的测量线路,使失调电压及其漂移的影响减小了5倍。本研究为传感器电桥测量系统设计中的放大器选择和测量方案的确定提供了理论指导。

A method to reduce the nonlinear error of a bridge using operational amplifier （op amp） feedback were introduced, the feedback conditions of canceling nonlinearity were found by circuit analyzing. Ignoring input bias current and input noise voltage of op amp in four linearity circuits,the out put expressions for affect of offset voltage on measuring system were given. The correction characteristic of each method was analyzed to attain optimal testing bridge circuit to reduce the errors of offset and drift by five times. The results show the method can provide a theory guidance for choosing op amp and determining method in bridge circuit measuring system.