Modeling avalanche multiplication for advanced high-speed SiGe bipolar transistors

For correct modeling of avalanche breakdown effects in bipolar transistors with the six transistor model, the multiplication factor M must be accurately described. However, as a simplification it is sometimes suggested to neglect its current dependence. We will show that this is not possible for advanced high-speed SiGe bipolar technologies. In this work, we present a practical model for M which takes the current into account as well. It allows simple parameter extraction and, moreover, can easily be used with standard circuit simulators. The model is verified for a fast pre-production SiGe technology by comparison to measurements.