Fast physical models for Si LDMOS power transistor characterization

A new quasi-two-dimensional (Q2D) model is described for microwave laterally diffused MOS (LDMOS) power transistors. A set of one-dimensional energy transport equations are solved across a two-dimensional cross-section in a “current-driven” form. This process-oriented nonlinear model accounts for thermal effects, avalanche breakdown and gate conduction. It accurately predicts DC and microwave characteristics as demonstrated by comparison with measured DC characteristics, transconductance, forward gain, S21, and large-signal gate and drain charges for a LDMOS transistor. The model is fast, taking less than 30 ms to extract a 50 point DC IDS-VDS characteristic and less than 5 ms to produce S-parameters at a single frequency.