Effect of PCB traces with continuous impedance perturbation on crosstalk immunity

In this paper, a non-uniform trace configuration to reduce crosstalk in printed circuit board (PCB) interconnects is investigated. The aim is to reduce crosstalk without incorporating additional PCB components in order to equalize propagation delays or modify inductive and capacitive couplings between the adjacent traces. This can be established by replacing a uniform victim trace on a PCB with a continuously varying-impedance trace that exhibits a lowpass filter (LPF) frequency characteristic. A simplified synthesis approach of the proposed trace impedance profile which is governed by a truncated Fourier series is presented. The proposed trace shows better crosstalk reduction results compared to conventional intervening guard trace schemes. Several configurations are discussed and the proposed non-uniform trace configuration is designed, implemented, and tested to demonstrate the improved crosstalk performance.