aaron_do
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Hi all,
I have just started looking at a 65 nm PDK, and I have the option of two FETs: nmos and RFnmos. Physically, the only difference is that the RFnmos has a guard ring around it, and also the polysilicon trace for the gate connection is extended on both sides of the FET (probably in order to reduce the series gate resistance).
However, I don't really want to use the FET with the polysilicon gate connection on both sides as later on i am going to model the connections to the transistor terminals in an EM simulator and I don't want the addtional connections to pass over the transistor itself (it may reduce the accuracy).
So instead I want to use the "normal" nmos transistor which does not have a guard ring in the layout. So knowing that the RFnmos is physically just an nmos + a guard ring, is this also true for the transistor model? The transistor uses a BSIM4.5 model. So does the RFnmos use an idential BSIM core model plus an additional model for the guard ring, or does the RFnmos include additional modeling to improve the accuracy at RF?
I have tried looking through the model files, but they are absolutely full of equations and parameters, and it isn't easy to compare them. All help is appreciated.
thanks, Aaron
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