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动态范围压缩电路的功能是,在不产生或只产生有限的谐波失真的条件下,从幅度变化范围较大的输入信号产生幅度变化范围较小的输出信号。本文介绍一种可以方便地改变压缩比的动态范围压缩电路。文中压缩比定义为:式中,U_(0max)为对应于最大输入信号 U_(imax)的输出电压值,U_(0min)为对应于最小输入信号 U_(imin)的输出电压值。当用正弦波作测试信号时,电压用有效值表示。该动态范围压缩电路见图1。第一级为主放大级,第二级为全波整流,第三级为直流放大。利用一对场效应管的漏-源极构成输入电桥的两个臂。BG_2栅极对交流接地,故其漏-源电阻为常数(记为(?))。输入信号强度改变时,送回 BG_1栅极的控制电压也随之改
The function of the dynamic range compression circuit is to produce an output signal with a small variation range from an input signal having a wide range of amplitude without producing or only generating limited harmonic distortion. This article describes a compression ratio can be easily changed dynamic range compression circuit. The compression ratio is defined as: where U_ (0max) is the output voltage value corresponding to the maximum input signal U_ (imax) and U_ (0min) is the output voltage value corresponding to the minimum input signal U_ (imin). When using a sine wave as a test signal, the voltage is expressed in rms. The dynamic range of compression circuit shown in Figure 1. The first stage is the main amplification stage, the second stage is full-wave rectification, the third stage is DC amplification. The drain-source of a pair of FETs forms the two arms of the input bridge. BG_2 gate to the AC ground, so the drain - source resistance is constant (marked as (?)). When the input signal strength is changed, the control voltage sent back to the gate of BG_1 is also changed