HeeSoo LEE

HeeSoo LEE

HeeSoo Lee is the DDR/SerDes product owner and an App Dev master scientist in the PathWave Software Solutions (PSS) group at Keysight Technologies. He has held several different positions since 1989 in Keysight/Agilent/Hewlett-Packard, including consulting business manager, technical marketing lead, and field applications engineer. Previously, he worked for Daeryung Ind. Inc. as a RF/MW circuit design engineer. He has over 30 years of design and simulation experience in RF, microwave, and high speed digital designs. He graduated with a BSEE degree from the Hankuk Aviation University, South Korea.

ARTICLES

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Via Characterization and Modeling By Z Input Impedance

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.


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