A compact IGFET model - ASIM.

This memo describes ASIM, a compact model for enhancement-mode MOS transistors. A detailed description of the model formulation is presented and the assumptions used in the derivation of model equations are stated. ASIM is generally applicable to MOS transistors with small physical dimensions, ion-implanted substrates, and lightly doped source and drain regions. All regions of transistor operation can be simulated using ASIM including the triode, saturation and subthreshold regions. Transient behavior of the MOS transistor is modeled with charge based circuit elements rather than capacitances. This ensures charge conservation in circuit simulation. Physical effects have been incorporated in the drain current equation and the charge expressions consistently, i.e. the effects of mobility reduction, carrier velocity saturation and channel length modulation are included in both. For versatility in circuit application, ASIM provides for the scaling of model parameters with device dimension and temperature.