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Simulators >> Circuit Simulators >> Explanation of stb analysis results YG, YL, ZG, and ZL
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Message started by Frank Wiedmann on Nov 7^th, 2025, 8:01am

Title: Explanation of stb analysis results YG, YL, ZG, and ZL
Post by Frank Wiedmann on Nov 7^th, 2025, 8:01am

In Virtuoso 23.1 ISR14 and Spectre 23.1 ISR13, the results YG, YL, ZG, and ZL have been added to the stb analysis (see page 9 of https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1OPP000001RAnV2AW). As the official documentation on these quantities is a bit incomplete from my point of view (I have asked for improvements in Case 46927677), here is a simple example that hopefully shows all the details.

Important points to note:

The PLUS pin of the iprobe is associated with ZL and YL; the MINUS pin of the iprobe is associated with ZG and YG.
ZL and ZG are determined by the insertion of a voltage source (same current on both sides).
YL and YG are determined by the insertion of a current source (same voltage on both sides).
ZL and ZG correspond to the impedances provided by the sprobe, but don't suffer from the numerical problems of the sprobe when very low impedances are connected (I had CCR 2029190 filed on this problem 7 years ago).