一种适用于低频小信号检测的放大电路

An Amplifier Circuit for Low Frequency and Small Signal Detection

针对微传感器输出的低频小信号,提出了一种基于"调制-放大-解调"思路的放大电路。该电路利用乘法器将输入信号调制至高频段放大,可以显著降低电路的低频噪声影响。相较于目前常用的斩波放大器,该电路可以克服时钟同步困难以及低频谐波分量干扰较大的缺点。该电路基于CSMC 0.5μm Mixed Signal工艺设计,仿真结果显示,在5V的工作电压下,可实现100倍以上放大,1/f噪声得到有效抑制。

For the micro-sensor＇s low frequency and small amplitude output signal, an amplifier circuit was presented based on the idea of “modulation amplification-demodulation”. The circuit adopted a multiplier to modulate the input signal to high frequency, and then amplified it. which could significantly reduce low frequency noise interferences. Compared to the currently used chopper amplifier, the problems in the chopping clock synchronization and the low frequency harmonic component interference were settled. The circuit was designed based on the CSMC 0.5 μm mixed signal process. The simulation results showed that the magnification was over 100 while the working voltage was 5 V, and the l/f noise was effectively suppressed.