As I tried to transfer Bsim3v3 model from cadence to hpads, I found inconsisent I-V characteristics between the two simulators...
I simulated the Ids-Vgs curve at Vds very small. While in simulation, I turned off all second-order effects (i.e. body-effect, poly-gate effect, short channel, narrow channel, mobility as a function of electric field) to make an ideal mosfet.
The simulated Ids does not increase linearly as Vgs increases in ADS. In cadence, the Ids increases linearly as Vgs increases, the latter is consistent with the model equations. And I checked carefully on the model parameters between ADS and cadence...they are same.
Does anyone know about this? I wonder whether ADS add some additional model in the bsim3v3. Because the supposed ideal mosfet doesn't behave ideal in ADS
Thanks
I simulated the Ids-Vgs curve at Vds very small. While in simulation, I turned off all second-order effects (i.e. body-effect, poly-gate effect, short channel, narrow channel, mobility as a function of electric field) to make an ideal mosfet.
The simulated Ids does not increase linearly as Vgs increases in ADS. In cadence, the Ids increases linearly as Vgs increases, the latter is consistent with the model equations. And I checked carefully on the model parameters between ADS and cadence...they are same.
Does anyone know about this? I wonder whether ADS add some additional model in the bsim3v3. Because the supposed ideal mosfet doesn't behave ideal in ADS
Thanks
One of our R&D engineers looked at your post and I got the following feedback:
"Please note that in the absence of 2nd order effects, and with Rds=0, and for sufficiently small Vds, the drain current, Ids, will be linearly proportional to (Vgs-Vth) but not Vgs, as shown in the Berkeley BSIM3V3 manual eq. (2.5.4).
In any case since you are observing a discrepancy between ADS and Spectre, we encourage you to report this case to the support team and provide your designs/netlists/etc for immediate investigation. The standard for ADS implementation of BSIM3 is Berkeley Spice, since Berkeley is the developer of BSIM3. Once support obtains this case, it will be compared with Berkeley Spice and appropriate actions will be taken accordingly"
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