Stefan Schippers02/07/2023, 11:05 AM
realized as poly over n-tap inside nwell ? or just as nmos (may be with some additional Vth adjusting implant)? Trying to figure out how
are realized. From @Tom picture above (specifically the arrow) it seems that nmoscaps are implemented as nmos, possibly with a Vth correction.
Tim Edwards02/07/2023, 1:56 PM
suffix that are the "true" varactors (poly over n-tap, and also poly over p-tap, which is not usually a characterized device). The ones without the suffix appear to be basic source-drain-tied FETs. But there is a separate device model for the source-drain-tied devices, which is why they have a separate device name. I'm not sure why a MOScap with a standard FET structure would need a distinct simulation model. So the MOScap FET devices are:
, while the varactor devices are
. (Then, to make life more complicated, there's the extended low-doped drain devices vs. the extended salicide-blocked drain devices. . .)
Robin Tsang02/12/2023, 4:40 AM