BXXXXXXX ND NG NS MNAME <AREA> <OFF> <IC=VDS,VGS>
Example:
B1 7 2 3 ZM1 OFF
ND, NG, and NS are the drain, gate, and source nodes, respectively. MNAME is the model name, AREA is the area factor, and OFF indicates an (optional) initial condition on the device for DC analysis. If the area factor is omitted, a value of 1.0 is assumed. The (optional) initial condition specification, using IC=VDS,VGS is intended for use with the UIC option on the .TRAN statement, when a transient analysis is desired starting from other than the quiescent operating point.
See the .IC statement Nodeset for a better way to set initial conditions.
MESFET Models (both N and P Channel)
The MESFET model is derived from the GaAs FET model of Statz et al (H.Statz et al., GaAs FET Device and Circuit Simulation in SPICE, IEEE Transactions on Electron Devices, V34, Number 2, February, 1987 pp.160, 169).
The DC characteristics are defined by the following parameters:
For:
the drain current is given by:
For:
the drain current is given by:
Two ohmic resistances, RD and RS, are included. Charge storage is modeled by total gate charge as a function of gate-drain and gate-source voltages and is defined by the parameters CGS, CGD, and PB.
MESFET Model Parameters -
| Name | Meaning | Units | Default |
| VTO | pinch-off voltage | V | -2.0 |
| BETA | transconductance parameter | A/V2 | 1.0E-4 |
| B | doping tail extending parameter | 1/V | 0.3 |
| ALPHA | saturation voltage parameter | 1/V | 2 |
| LAMBDA | channel length modulation parameter | 1/V | 0 |
| RD | drain ohmic resistance | W | 0 |
| RS | source ohmic resistance | W | 0 |
| CGS | zero-bias G-S junction capacitance | F | 0 |
| CGD | zero-bias G-D junction cap | F | 0 |
| PB | gate junction potential | V | 1 |
| KF | flicker noise coefficient | - | |
| AF | flicker noise exponent | - | |
| FC | coeff for forward-bias depletion cap | - |
* The parameter scales with area.
