摘要目的 设计一种适用于微弱直流信号放大的前级放大电路.方法 利用频域分析法分析微弱直流信号的频域特性以及信噪情况,确定信号主要信息所在频域范围;同时,求解微弱直流信号放大电路系统函数,并利用微弱直流信号主要信息所在频域范围指导微弱直流信号前级放大电路设计.为验证该系统函数的正确性,建立了前级放大电路模型并实际焊接了不同容量电容(10,1×103,1×104,1×105 pF)的放大电路;通过电路实验,测量了不同容量下电路的输出信号幅值.结果 前级放大电路输出电动势和理论模型计算值相符.结论 该前级信号放大电路模型和实际相符.可以利用频域分析法有针对性地设计微弱直流信号放大电路.

abstractsObjective The purpose of this study was to design a prime amplification circuit which was suitable for weak direct current's (DC) amplification. Methods By using frequency-domain analysis to acquire the characteristic of weak DC signal and the situation of signal and noises, the main message of the signal can be certified in particular frequency range. The system function had been built and the prime amplification circuit was designed by the reference of the frequency range which contained the main message of the weak DC signal.To certify that the system function was correct, a mould amplifier was made with different capacitances of 10, 1 ×103,1 ×104,and 1 ×105 pF, respectively. Amplitude of output voltages were measured via electric experiments.Results The output voltages measured were consistent with that of calculated value from theoretical model.Conclusion The mould amplifier circuit is consistent with actual circuit. It was a useful way to design weak DC signal amplifier by using frequency-domain analysis.