Reduction of analog noise in PCB for photodetection system

Most of photodetection systems need to be satisfied high rate of data processing and high frequency. In response to the demands, EMI (Electro-Magnetic Interference) has emerged as an important factor to be considered for the photodetection system stability. In this study, experiments were carried out on methods of controlling impedance in the stage of design and improving signal integrity of PCB trace for consideration of the EMI problem. Programmed time varying electric field (vectorial signal) was composed for minimized loop in the layout with 8 types of traces as same schematic and examined their structural effects on the trace. In conclusion, the stacked structure was found to be more effective to control impedance. This study is a preliminary work for more complicated cases, providing the basic theory to reduce noises effectively with the shape of return path and more various vectorial signals.