基于AD603的时变增益放大器的实现

探地雷达回波信号具有动态范围大、频带宽等特点，如果不对回波信号进行处理直接进行A／D转换，则会出现动态范围不匹配的问题，严重影响雷达的探测深度和分辨率。为此，本文采用AD603设计了一时变增益放大器对回波信号进行处理，通过对不同时间的回波信号给以不同的增益来补偿A／D转换器的动态范围的不足，达到与回波信号动态范围相匹配的目的。本文给出了详细的设计思想和原理电路图，实测结果表明，文中所设计的时变增益放大器能满足雷达系统的需求，具有很强的实用价值。
关键词：探地雷达；时变增益；动态范围
Abstract：The echo of ground penetrating radar(GPR)has a characteristic of large dynamic rang~ If the echo of GPR
doesn’t be processed and direct is adopted analog-to-convert，the dyn amic range of analog-to-digital converter(ADC)in data acquisition circuit can’t match the need of GPR system and the problem will affect the exploration depth and resolution of GPR．In order tO solve the problem，a time varying gain(TVG)method which attenuates the strong signal reflected from shallow layer while am plifies the weak signal reflected from deep layer is presented in the paper．A novel voltage-controlled amplifier(VCA) 03 is used in the design of VGA．The scheme of design is given in the paper．The experiment measure result testifies that the circuit can satisfy the need of GPR and iS valid．
Keywords：GPR；time varying gain；dyn amic range