一种可自动跟踪频率的900移相全通滤波器

A 900 Phase-shift All-pass Filter of Automatic Frequency Tracking

全通滤波器是锁相放大器、信号发生器等仪器产生等幅正交正弦波信号的常用电路。当信号频率改变时,通常需要手动调节全通滤波器的参数。本文提出一种可自动跟踪频率的全通滤波器,采用相敏检测电路检测两路正弦波信号的相位差,根据相位差自动调节电子模拟电阻的阻值,从而维持全通滤波器输入输出正弦信号相互正交。实验结果表明,该900移相全通滤波器跟踪频率范围较宽、相位及幅值精度较高,具有良好的应用价值。

All-pass Filter is often used as a continuous orthogonal signal circuit for such instruments as lock-in amplifier and signal generator. It usually requires manual adjustment of all-pass filter parameters When the frequency changes. In this paper, an all-pass filter of automatic frequency tracking is presented. The filter which uses a phase-sensitive detection circuit for detecting the phase deference of two sinusoidal signals and adjusts automatically the resistance values of the electronic resistor based on phase difference in order to maintain mutually orthogonal signals of the input and output. The experiment results show that the 900 phase-shift all-pass filter of automatic frequency tracking have such advantages as wide frequency tracking range and high phase and amplitude precision, and is very useful in practice.