Nathan Hirsch is lead signal integrity engineer at Monsoon Solutions Inc. He received his BSEE from Eastern Washington University in 2014, and is currently in-progress on his MSEE from the University of Washington. He has worked in Bellevue, Washington for Monsoon Solutions Inc. since 2014, specializing in high-density consumer electronic circuit board design and prototyping. Nathan is interested in introducing signal integrity concepts to PCB Designers to improve circuit board design flows.
In high-speed digital channel design, vias are everywhere and are becoming very crucial elements to the channel performance. Especially with the higher data rate requirements in mobile, networking, and data center applications, the effect of vias in a design is very noticeable. Design engineers have traditionally used time domain reflectometry (TDR) as a tool to characterize and optimize via designs, yet the TDR approach comes with shortcomings such as demanding shorter rise-time step signal or larger bandwidth S-parameters, and inaccurate read-out on the via impedance.
In this article, we propose a simple and effective Z-input impedance method that augments the traditional TDR method for characterizing and optimizing via designs in much faster speed systems.