Dear all,
Actually I am trying to find the equivallent known capacitors for RF design problem by Spectre (Cadense) and HSPICE with the TSMC 0.18 um model.
I find the values of Cij (i,j=Gate,Bulk,Source,and Drain) in Spectre and the Cito (i=Gate,Bulk,Source,and Drain) and Cgs and Cgd from HSPICE.
I really don't know what is the Cgs, Cgd, Cgb, Cbs,snd Cbd that we use in AC or RF simulations.
I read the Spectre help files and HSPICE and I found that these capacitors known as transcapacitors are calculated as (Cij=dQi/dVj) and some of them are negative.
When I see the Spectre model There are intrinsic and overlap (and fringing) capacitors. The intrinsic caps are calculated by the aforementioned equation and the overlap capacitors are calculated by CGSO, CGSL process parameters.
Therefore, I calculated all of these parameters based on the spectre and BSIM3V3.1 model but actually there is a mismatch between them.
If you provide me some thing about just approximation of Cgs,Cgd,Cgb, Csb,Cdb I appreciete your help
Thanks a lot