基于FPGA的增益可调微弱信号采集系统设计

Design of Gain-adjustable Weak Signal Acquisition System Based on FPGA

针对以往采集电路中放大倍率固定,适用的采集环境单一,不可灵活调理实际微弱信号的现状,设计了基于 FPGA 的增益可调微弱信号采集系统,该系统以 FPGA 为核心,以集成运算放大器OP37G,模拟开关 DG611DY 组成增益可调放大电路,具备了×0.5,×2,…,×100,×200 等 10 种放大倍率可编程控制的功能,以高精度模数转换芯片 AD7865 为采集芯片,实现了高精度微弱信号的采集。试验结果表明:系统在多种微弱信号环境下经增益电路放大后,各通道采样精度均能达到 0.1%。系统可灵活应用于多种微弱信号采集环境,稳定可靠,已成功应用于某微弱信号测试场合。

Aiming at the current situation that the amplification ratio of the previous acquisition circuit was fixed, the appli cable acquisition environment was single, and the actual weak signal cannot be flexibly conditioned, a gain-adjustable weak sig nal acquisition system based on FPGA was designed. The system used FPGA as the core, integrated operational amplifiers OP37G and analog switches DG611DY to form a gain-adjustable amplification circuit, which had 10 kinds of programmable con trol functions such as × 0.5,× 2 ...×100,×200, etc. and used the high-precision analog-digital conversion chip AD7865 as the acquisition chip to realize the acquisition of high-precision weak signals. The experimental results show that the sampling ac curacy of each channel can reach 0.1 % after the system is amplified by gain circuit in various weak signal environments. The system can be flexibly applied to various weak signal acquisition environments, is stable and reliable, and has been successfully applied to a weak signal testing occasion.