Impact of Anti-resonance Caused by Via Structure on Signal Integrity in High-Speed Circuits

In high-speed circuits, the via structure is an important factor of impedance discontinuity. At a certain frequency, its parasitic parameters cause a sudden change in impedance, causing anti-resonance problems. This paper analyzes the causes of a sudden change in impedance caused by the via structure and the path of signal reflow on the high-speed multilayer PCB, then explains the theory and problem of anti-resonance, HFSS software is used to model and simulate. Finally, solutions for eliminating anti-resonance and improving signal integrity are proposed from changing the size of via anti-pad, increasing short circuit vias and optimizing the entire PCB design (including laminate design and PCB's material). The feasibility of the solution is also verified. These solutions provide practical reference for the design of high-speed circuits.