Ultrasim does not converge with BSIMBULK model

Not sure why that would be, because the model implementation is identical to Spectre. The DC is different in Ultrasim (because it's a different simulator) but the model implementation is the same. You should contact customer support so that we can investigate why it's having a problem.

Andrew.

Andrew,

When I look at the Virtuoso UltraSim Simulator User Guide, Product Version UltraSim 18.1, December 2019. I do not see any BSIM BULK (formerly called BSIM6) in the list of supported MOSFET models.

Can it be the reason why, Ultrasim can not simulate my netlist ? I am using a BSIM BULK model ?

The MOSFET models supported by the simulator are listed below :

Level 49 and Level 53     BSIM3v3 versions 3.0, 3.1, 3.2, 3.21, 3.22, 3.23, 3.24, and 3.30
Level 54                           BSIM4 versions 4.0, 4.1, 4.2, 4.3, 4.4, and 4.5
Level 69                           PSP model
Level 57 and Level 59      BSIM3SOI versions 2.2, 2.21, 2.22, 2.23, 3.0, 3.1, and 3.2
(Level 59 is a                   SOI FD model and the Virtuoso UltraSim simulator only supports this model in s mode)
Level 70                           BSIMSOI 4.0
Level 61                          RPI a-Si TFT model
Level 62                           RPI Poli-Si TFT model versions 1 and 2
HVMOS (Level 101) Cadence proprietary high-voltage MOS model
Level 50 Philips              MOS9 model
Level 63 Philips              MOS11 model

EKV (Level 55)

This is just a matter of the documentation list of model numbers not having been updated.

UltraSim supports bsim6/bsimbulk. It also corresponds to model level 77 so both these netlists simulate OK:

// testbsimbulk.scs

model nch bsimbulk type=n

Vd (d 0) vsource dc=1
Vg (g 0) vsource dc=1
M1 (d g 0 0) nch w=1u l=0.2u

dc dc

and

* testbsimbulk.cir

.model nch nmos level=77

Vd d 0 1
Vg g 0 1
M1 d g 0 0 nch w=1u l=0.2u

.op

.end

Andrew