基于VCA822的正弦信号发生器程控放大器

Digital Programmable Amplifier of the Sine Signal Generator Based on VCA822

DDS芯片产生的信号幅值不可控制,且随着频率改变,输出信号幅值在一定范围内改变,然而作为信号源常常需要信号幅值的精确控制。本文利用TI公司的可控增益放大器VCA822设计了增益自动调整电路和程控放大电路。实现将DDS芯片产生的不确定幅值的正弦波通过增益自动调整电路后,变化为固定幅值的正弦信号,再通过程控放大器完成输出正弦信号幅值0.5V^5V程控可调。

The signal amplitude produced by DDS chip is generally uncontrollable,and the output signal amplitude changes within a certain range with frequency changes.However,precise control of signal amplitude is needed as signal source.Using controllable gain amplifier VCA822 of TI,the author designed an automatic gain adjustment circuit and a programmable amplifier.This makes it possible that the amplitude uncertain sinusoidal wave produced by DDS chip is changed into amplitude fixed sinusoidal signal through the gain automatic adjustment circuit and then theprogrammability and adjustability is realized through outputting sinusoidal signal amplitude 0.5V-5V by the programmable amplifier.