High frequency AC equivalent circuit model of Si/SiGe HBTs

In applications based on Si/SiGe HBTs, veracity of AC equivalent circuit model is the key element during circuit designs. To avoid errors in available ranges for bipolar devices from f(beta) to f(T), we developed a novel model with accurate circuit form equations and circuit descriptions of Y and H type AC parameters. The novel HBTs' model represents DeltaE(g) between two sides of heterojunction, and legible differences with BM in capacitance proportion caused by decreasement of emitter base doping rate and in the ratio to capacitance and resistance by the reduction of Results of these differences make the novel base model's circuit form varies from BJTs' in high frequency ranges.