Systematic direct parameter extraction with substrate network of SiGe HBT

A systematic approach to directly extract the equivalent circuit of a heterojunction bipolar transistor (HBT), including the substrate network, is developed. All parameters are extracted from the measured S-parameters. The substrate network is accurately extracted by measuring the collector port. An equivalent circuit without substrate effects can be extracted by systematically analyzing and solving the two-port network equations. This technique is validated with fabricated devices in silicon germanium (SiGe) technology from 50 MHz to 26.05 GHz. The extracted results are in excellent agreement with the measured results.