Guest Column | July 30, 2014

EM De-Embedding Magic – Part 2: Lots Of Ports, All Talking To Each Other!

To access this content, please Register or Sign In.

By James C. Rautio


By Dr. James C. Rautio, President, CEO, and founder, Sonnet Software, Inc.

In part I, I described how I came up with the EM port calibration theory that we have been using very successfully for nearly 30 years. It is so simple. To de-embed a single, lonely port, just EM analyze a 2-port through line of length L, and a second one of length 2L, do some magic math (described in Part I and in [1] and [2]), and we have beautiful, fully de-embedded EM analysis data for that lonely port. (If we have additional lonely ports, just repeat the process for those ports, one at a time, as well.)

Central to that calibration and de-embedding procedure is the conversion of S-parameters into ABCD-parameters and back again. We usually measure (or EM analyze) one S-parameter matrix for each frequency of interest. If we are calibrating a single port, our calibration standards (the through lines) are 2-port devices, and our matrix is a complex (i.e., it has real and imaginary parts) 2×2 matrix. We calibrate and de-embed at each frequency, one frequency at a time. Both the S-parameters and the ABCD-parameters that we use for calibration are 2×2 matrices.