General form:

MXXXXXXX nd ng ns nb mname <m=val> <l=val> <w=val>
+ <ad=val> <as=val> <pd=val> <ps=val> <nrd=val>
+ <nrs=val> <off> <ic=vds, vgs, vbs> <temp=t>

Examples:

M1 24 2 0 20 TYPE1
M31 2 17 6 10 MOSN L=5U W=2U
M1 2 9 3 0 MOSP L=10U W=5U AD=100P AS=100P PD=40U PS=40U

Note the suffixes in the example: the suffix `u' specifies microns (1e-6 (m)) and `p' sq-microns (1e-12 (m^{2})).

The instance card for MOS devices starts with the letter 'M'. nd, ng, ns, and nb are the drain, gate, source, and bulk (substrate) nodes, respectively. mname is the model name and m is the multiplicity parameter, which simulates `m' paralleled devices. All MOS models support the `m' multiplier parameter. Instance parameters l and w, channel length and width respectively, are expressed in meters. The areas of drain and source diffusions: ad and as, in squared meters ((m^{2})).

If any of l, w, ad, or as are not specified, default values are used. The use of defaults simplifies input file preparation, as well as the editing required if device geometries are to be changed. pd and ps are the perimeters of the drain and source junctions, in meters. nrd and nrs designate the equivalent number of squares of the drain and source diffusions; these values multiply the sheet resistance rsh specified on the .model control line for an accurate representation of the parasitic series drain and source resistance of each transistor. pd and ps default to 0.0 while nrd and nrs to 1.0. off indicates an (optional) initial condition on the device for dc analysis. The (optional) initial condition specification using ic=vds,vgs,vbs is intended for use with the uic option on the .tran control line, when a transient analysis is desired starting from other than the quiescent operating point. See the .ic control line for a better and more convenient way to specify transient initial conditions. The (optional) temp value is the temperature at which this device is to operate, and overrides the temperature specification on the .option control line.

The temperature specification is ONLY valid for level 1, 2, 3, and 6 MOSFETs, not for level 4 or 5 (BSIM) devices.

BSIM3 (v3.2 and v3.3.0), BSIM4 (v4.7 and v4.8) and BSIMSOI models are also supporting the instance parameter delvto and mulu0 for local mismatch and NBTI (negative bias temperature instability) modeling: