Spectre-Specific Parameters

Some of the following parameters are left in the model for backward compatibility to other Spectre^® circuit simulator models.

Instance Parameters

The instance parameters mentioned in the table below help you in performing mismatch analyses. They represent the statistical variation of the threshold voltage (vth0), the mobility (u0), the body bias coefficient (k1) and the subthreshold swing factor (Nfactor). These parameters are implemented in the following manner:

Parameter	Unit	Description
`Delvto`	v	shift in zero-bias threshold voltage vth0. Default value is `0.0`.
`Nulmu0`		Mobility multiplier. Default value is `1.0`.
`Delk1`	v^1/2	shift in body bias coefficient k1. Default value is `0.0`.
`Delnfct`		Shift in subthreshold swing factor. Default value is `0.0`.

The checking of these parameters is as follows:

If Mulu0 < 0.0 and Paramchk returns a warning message, reset Nulmu0 to 1.0.
If Delk1 < -K1 (after binning) and Paramchk returns a warning message, reset Delk1 to 0.0.

The parameters are added whether Vto and K1 are given (specified by you or computed internally when not specified). Mulmu0 is multiplied after binning.

Model Parameters

Parameter	Description
`ad`	Area of drain diffusion. This is an instance parameter in Spice, but may be specified as a model parameter in Spectre.
`alarm`	Forbidden operating region. Can be set to `none`, `off`, `triode`, `sat`, `subth`, or `rev`. Spectre will issue a warning if your device’s operating point enters this region.
`as`	Area of source diffusion. This is an instance parameter in Spice, but may be specified as a model parameter in Spectre.
`bvj`	The junction reverse breakdown voltage. Spectre checks this at the DC operating point, and also on each step of the transient simulation. Spectre issues a warning if the bulk-drain voltage exceeds this voltage.
`cbd`	Bulk-drain zero bias junction capacitance.
`cbs`	Bulk-drain zero bias junction capacitance.
`cta`	Junction capacitance temperature coefficient.
`ctp`	Sidewall junction capacitance temperature coefficient.
diomod	Controls the junction models. If `diomod=1` (default value), the Spectre junction model is used. The equations are described in Chapter 12: Common MOSFET Equations. If `diomod=0`, the Berkeley BSIM3v3 junction model is used.
`drout`	DIBL effect on rout coefficient.
`dskip`	Allows the substitution of a simple `pwl` model for the diode current if it falls below 0.1*iabstol.
`eg`	Energy band gap.
`fc`	Forward bias depletion capacitance threshold.
`fcsw`	Sidewall forward bias depletion capacitance threshold.
`gap1`	Band gap temperature coefficient.
`gap2`	Bandgap temp offset.
`hdif`	Length of heavily doped diffusion.
`imax`	Maximum current.
`imelt`	Explosion current. The junction current is linearized after this current is exceeded.
`jmax`	Maximum current density.
`jmelt`	Explosion current density.
`is`	Bulk-junction reverse saturation current.
`l`	Default channel length, if not specified on the instance.
`ldif`	Lateral diffusion beyond the gate.
`lgcs`	Gate to contact length of source.
`lgcd`	Gate to contact length of drain.
`meto`	Metal overlap in fringing field.
`minr`	Minimum resistance.
`nrd`	Default number of drain squares. This is an instance parameter also.
`nrs`	Default number of source squares. This is an instance parameter also.
`pd`	Drain perimeter. This is an instance parameter also.
`ps`	Source perimeter. This is an instance parameter also.
`pta`	Junction potential temperature coefficient.
`ptp`	Sidewall junction potential temperature coefficient.
`rd`	Drain resistance.
`rdc`	Drain contact resistance.
`rdd`	Scalable drain resistance.
`rs`	Source resistance.
`rsc`	Source contact resistance.
`rss`	Scalable source resistance.
`sc`	Contact spacing.
`tlev`	DC temperature selector.
`tlevc`	AC temperature selector.
`trd`	Temperature param for drain resistance.
`trise`	Temperature rise from ambient.
`trs`	Temperature param for source resistance.
`type`	Specifies `nmos` or `pmos`, since the primitive name is bsim3v3.
`xl`	Length variation from masking and etching.
`xw`	Width variation from masking and etching.
`w`	Default channel width, if not specified on the instance.
`warn`	Parameter to turn warnings off and on.
`wnoi`	Channel width at which noise parameters extracted.
`vbox`	Oxide breakdown voltage.

n in the Spectre^® circuit simulator is nj in Berkeley. nqsmod is an instance parameter for Berkeley, but both an instance and model parameter for the Spectre circuit simulator. level=11 in the Spectre simulator, but level=8 in Berkeley. The ijth parameter (diode-limiting current) is aliased to the Spectre simulator’s imelt parameter. Some of the Spectre-specific parameters can affect the behavior of the model in such a way to make the model incompatible with other simulators. Cadence recommends that care be taken when using these parameters.

See spectre -h bsim3v3 for more details about these parameters.

Spectre Circuit Simulator Components and Device Models Reference
Product Version 23.1, June 2023