Simulation and analysis of via effects on high speed signal transmission on PCB

Via effects on signal transmission and reflection are presented in this paper. The via interconnects a transmission line on a high-speed multi-layered PCB. By modeling the via´s equivalent circuit, calculating its reactance values and analyzing the effects of its capacitance and inductance on signal transmission, a conclusion is drawn that the higher the operation frequency is, the more attention should be paid to the via. A simulation of a microstrip, with or without a via, on a 4-layered PCB is performed to obtain the S-parameters under different frequencies. The results also verify the conclusions above.