A new approach for directly calculating the heterojunction bipolar transistor (HBT) equivalent circuit from measured S-parameters is presented. Analytically derived rather than fitted solutions are obtained in this way. Extrinsic as well as intrinsic element values are computed without the use of special test structures or additional measurement steps. Bias-dependent results for base resistance, collector resistance, base-collector capacitance, base transport factor, and base and collector transit times are discussed.
