Modeling Non-Quasi-Static Effects in SiGe HBTs Using Improved Charge Partitioning Scheme

The applicability of a partitioned-charge-based non-quasi-static (NQS) model is investigated using exact solutions for 1-D bipolar transistors. Limitations of the model to accurately predict $y_{21}(\omega )$ are overcome by further delaying the partitioned minority charge associated with the collector. A corresponding small-signal time-domain model is derived. The proposed model effectively includes the delays within both the quasi-neutral base and base–collector space-charge regions. Using only two extra nodes over the quasi-static bipolar transistor model HICUM, the NQS model is implemented using Verilog-A. The simplicity of the model yields straightforward parameter extraction techniques. Modeling results show excellent agreement with numerically simulated data.