A compact IGFET model-ASIM

A description is given of ASIM (AT&T short-channel IGFET model), a circuit-level model for enhancement-type MOSFETs. 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, which 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. The ASIM model accounts for effects due to device dimensions and temperature. The performance of ASIM under DC and transient conditions is evaluated by comparing the current and voltage at the terminals with that of detailed physical simulations and measurements. The results agreed well with that of two-dimensional device simulations and measurements.<
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