Routing Aspects in PCB Design for High Frequency Circuits

Abstract

Nowadays the high-speed communication systems involve also high data rates with minimum error numbers. Differential transmission lines are a good solution to mitigate the different types of noise which inevitably occur and affect the signal. However, this comes with a disadvantage: the signal skew. The meander lines are used in Printed Circuit Board (PCB) to compensate the aforementioned problem. In addition, this method improves the signal integrity, and it is a popular choice for signals synchronization. In this paper, a study of the routing performances for a high-speed circuit at high frequencies is presented. The goal is to determine the optimum meander shape and the maximum speed at which the circuit operates. The performance evaluation was done in terms of S- parameters and the reflections level simulated with Time-Domain-Reflectometry (TDR) function. For simulations, a PCB with 2circuits of Ethernet type signals is considered. The signals are propagated through different PCB layers, from a line-separation relay to an integrated circuit. A series of bits was transmitted from the relay through the equivalent filter of the lines to the integrated circuit. The results showed a slight signal attenuation due to the mismatch of the impedance.