Research on acquisition system of multichannel weak photocurrent

This paper make experiments and analyze with the acquisition system of multichannel weak photocurrent for Laser particle size analyzer. It is found using analog multiplexers directly switching multi-channel photocurrent will have a pulse spike. Through the analysis of photocurrent source output port, it was found that distributed capacitance will cause a pulse spike after switch closed. Then proposed the existence model of distributed capacitance in photocurrent source output port and the method of distributed capacitance discharge before switch in each channel. Experiments show that this design can significantly eliminate pulse spike, increase the speed of acquisition system.