多路光电流采集的前置放大

Pre-Amplification of Multichannel Photocurrent Acquisition

在常规多路光电流采集系统的前置放大电路中,一般采用各路先独立进行I/V转换,然后再切换进行A/D转换的方法。针对I/V转换电阻参数的分散性所导致的各路转换增益不同,各路之间存在分散性误差的问题,提出了电流直接切换方案,即利用模拟开关先切换多路电流然后进行精密I/V转换,有效地解决了上述问题,彻底消除了原理性误差。对新方案进行了初步的理论分析和实验,给出了实验结果。实验证明该方案达到预期效果。

I/V conversion in each channel and then selecting one - channel voltage to A/D conversion by using analog multiplexer is generally used in the preamplifier of multi - channel photo - current, however, because of the decentralization of resistance, there is an obvious error in the I/V conversion. The paper advanced a new method which is selects one - channel current directly. First selecting one - channel current and then I/V conversion by using appropriate analog multiplexer are adopted. This mettmd can effectively resolve above question and complefeiy eliminate errors in principle. Primary analyses in theory and experiment are provided. The result shows thatthis method has achieved anticipative purpose.