宽动态可变增益放大器的设计

摘要

In order to obtain the stable signal, it demands the gain of receiver automatically change when the received signal changes within a wide dynamic range in the communication receiver. It means that high performance receiver should put forward stricter requirements to variable gain ampliifer. The paper researches and designs the structure for wide dynamic variable gain ampliifer. Based on BiCMOS, this essay aims at the research and design of the wide dynamic variable gain ampliifer with the differential input common emitter structure. The MOS switch which changes the resistance of collector and emitter together with delay control technology contributes to the wide dynamic gain. The chip is simulated by using Cadence’s Spectre software and implementted by using CSMC 0.5μm process. Simulation results indicate that dynamic range of gain is from 0 to 60 dB;it receives the frequency from 20 MHz to 90 MHz, and has the power dissipation less than 20 mW.%在通信接收机中，当接收的信号强度变化很大时，要求接收机前端的增益随接收信号强度在很宽的范围内自动变化，以输出稳定信号，因此高性能接收机对可变增益放大器提出了更高的要求。设计基于BiCMOS工艺，采用差分输入共射级结构，对宽动态可变增益放大器进行了研究与设计，通过MOS开关改变集电极和发射极电阻以及延迟控制技术，达到宽动态增益的效果。仿真结果表明，三级放大器的增益动态范围为0~65 dB，频率范围为20~90 MHz。