An equivalent circuit model for the identification of the stub resonance due to differential vias on PCB

Abstract

The modern telecommunication equipments consist of boards connected by thick backplanes where differential traces on different layers transmit high speed digital signals. These signals switch from different layers by means of plated through holes that, when not used, are stubs introducing dips on the insertion losses of the used traces. The paper presents an algorithm for modeling differential vias connected to differential traces, so to evaluate the resonance frequency due to the stubs connected to the vias.