Hi, Dear all
I have a question on modeling SMD capacitor. I used a self-developed test fixture on the laminate and measured SMD capacitors with calibrated micro-probes, in both series and shunt mode. After de-embedding, I used series mode data to derive the SMD parameters and it can agree with vender’s data. So, I think my de-embedding calculation is OK. However, my questions is why the resonate frequency in series and shunt mode is different? For example, S11 in series mode has a resonate trap at 2.7GHz, while S21 in shunt mode has a resonate trap at 4.3GHz. The equivalent model can not explain it.
I guess that in shunt mode, because GND terminal of SMD capacitor is connected to a large ground plane, the parasitic inductance and resistance of this terminal is missing. Is this reasonable? Any better explanation of the resonate frequency shifting?
Thank you.