InGaAs/InP DHBT small‐signal model up to 325 GHz with two intrinsic base resistances

Abstract In this paper, a novel small‐signal equivalent‐circuit model of terahertz InGaAs/InP double‐heterojunction bipolar transistor (DHBT) is presented. Two intrinsic base resistances are introduced to represent the nonuniform extrinsic impedance of base‐emitter and base‐collector junctions separately. This treatment makes the high‐frequency model more close to the triple‐mesa InP DHBT structure. Systematical parasitic parameter extraction method and intrinsic element initialization of a 0.5 μm * 5μm InGaAs/InP DHBT are presented. As a high‐frequency device model, inter‐electrode parasitic capacitances are calculated by three‐dimensional electromagnetic simulation. The proposed model results in a good agreement with measured multibiased S ‐parameters up to 325 GHz.