A charge conserving non-quasi-state (NQS) MOSFET model for SPICE transient analysis

An analytic charge-conserving non-quasi-static (NQS) model is derived for long-channel MOSFETs and has been implemented in SPICE3. The model is based on approximate solutions to the transient current continuity equation, an analytic equations are derived for node charges using the charge-sheet formulation. The NQS effects in several test circuits, which include a pass transistor, a CMOS inverter chain, and a differential sample-hold circuit, are stimulated. Excellent agreements have been observed among this work, PISCES (2-D device simulation), the 1-D numerical simulation, the multiple lump model, and CODECS (a mixed device and circuit simulation). However, large differences have been observed between this work and conventional quasi-static (QS) models. The model computation time of this work implemented in SPICE3 is about 2-3 times larger than those of QS models (BSIM, Level-2 Meyer) in SPICE3.<
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