I understand that you are encountering negative R and G values in the high-frequency range when using the "s2rlgc" function, which is not the intended behavior.
Based on my understanding, I would like to offer an explanation for the discrepancies you are observing.
- An initial consideration could be that the .S2P file may contain noise or measurement errors.
- The "s2rlgc" function is designed to model structures with a shared ground between both sides. If your structure does not meet this criterion, the "s2rlgc" function may not operate as intended, resulting in inaccurate outputs.
- Behind the scenes, the "s2rlgc" function employs the "Eisenstadt" algorithm, which is effective for high-quality S-parameter data. However, it struggles when S-parameters exhibit significant non-transmission-line effects, which could contribute to the negative values observed.
- As referenced in the documentation for the "s2rlgc" function, that directly calculating RLCG parameters from measured S-parameters is not considered viable for GHz frequencies.
I hope this helps.
