纳米光栅微陀螺前置放大电路的设计与分析

Design and analysis of preamplifier for nano-grating micro-gyroscope

针对纳米光栅微陀螺输出微安甚至皮安级的微弱电流信号,设计微弱电流信号的前置放大电路,研究微弱电流信号检测与电路稳定性的理论,提出一种低成本、低噪声、高信噪比的微弱电流检测方法,即高阻型的I-V转化法,并给出高阻型I-V转化电路的响应带宽计算公式以及电路稳定性的分析方法。通过搭建测试台,对电路性能及功能进行实际测试。实验结果表明:该电路可对皮安级的微弱电流信号进行检测放大,电路灵敏度为10 mV/pA,最大检测误差为1.5%(当输入微弱电流值>10 pA时),满足纳米光栅微陀螺的微弱电流检测的需求。

In this paper, a preamplifier circuit of weak current signal was designed for the output of micro- ampere or even pico-ammeter level of Nano-grating micro-gyroscope. The theory of weak current signal detection and circuit stability was studied. A weak current detection method of high resistance I-V transformation type with low cost, low noise and high signal-to-noise ratio was proposed. The calculation formula of response bandwidth of high resistance I-V converter circuit and the method of circuit stability analysis were given. The circuit performance and function were tested by setting up a test bench. The experimental result shows that the circuit can detect and amplify the weak current signal of pA level. The circuit sensitivity is 10 mV/pA, and the maximum detection error is 1.5%(when the input weak current value is greater than 10 pA). This performance shows that the circuit can meet the need of weak current detection for nano-grating micro-gyroscope.