Use model and element statements to select the diode models. The model statement's LEVEL parameter selects the type of diode model used:
You can design Zener, Schottky barrier, and silicon diffused diodes by altering model parameters for both LEVEL 1 and LEVEL 3. LEVEL 2 does not permit modeling of these effects. For Zener diodes, the BV parameter is set for an appropriate Zener breakdown voltage.
If you do not specify the LEVEL parameter in the .MODEL statement, the model defaults to the nongeometric junction diode model, LEVEL 1.
Use control options with the diode model to scale model units, select diffusion capacitance equations, and change model parameters.
Control options related to the analysis of diode circuits, as well as other models, include DCAP, DCCAP, GMIN, GMINDC, SCALE, and SCALM. Specify these models using the .OPTIONS statement.
Use the scale element option, SCALE, to scale LEVELs 2 and 3 diode element parameters. Use the scale model option, SCALM, to scale LEVELs 2 and 3 diode model parameters. LEVEL 1 does not use SCALE or SCALM.
Include SCALM=<val> in the .MODEL statement to override global scaling that uses the .OPTION SCALM=<val> statement in a diode model.
The DCAP option selects the equations used in calculating the depletion capacitance (LEVEL 1 and LEVEL 3). The option DCCAP invokes calculation of capacitances in DC analysis.
Include the DCAP=<val> in the diode's .MODEL statement to override the global depletion capacitance equation selection with the .OPTIONS DCAP=<val> statement.
Diode convergence problems often occur at the breakdown voltage region when the diode is overdriven or in the OFF condition. To achieve convergence in such cases, include a nonzero value in the model for the series resistor parameter RS, or increase GMIN (the parallel conductance Star-Hspice automatically places in the circuit). You can specify GMIN and GMINDC in the .OPTIONS statement.
The diode control options follow: