Cadence - How to find device capacitance

[@becermis]

Great content. Thanks!

[@pablomarco5118]

Many thanks prof!

[@kirin9987]

Thank you for your kind explanation. I wonder why the dc simulation result is so different from the s parameter sim. Can you give me your opinion?

[@wallingphd]

The DC simulation is just based on the device model, but does not include estimates of metal capacitance due to layout parasitics. You can add a few more terms (e.g., Coverlap, Cjs, etc.) to get a closer approximation, but the safest bet is to just use the SP.

[@kirin9987]

@@wallingphd thank you!

[@mensh__]

I think the xval function with the psp sim would return -1 to 1 GHz. So, you should add the pss freq to that.

[@wallingphd]

The susceptance is linearly increasing with frequency, and the value in the plot is the correct value at the offset. Hence, we should not add the pss frequency to it. You can verify by setting the PSP frequency range to absolute and sweeping from frf +/- offset (e.g., 4.6GHz to 6.6GHz in this case). The result will be the same, albeit there will not be a divide by 0 in the middle of the range.

[@yabiliao8779]

thanks!