InGaP/GaAs Heterostructure Bipolar Thansistors

Small-signal modeling and microwave noise§characterization of §InGaP/GaAs HBTs will be explored. Device physics,§analytical §extraction and numerical optimization are§incorporated to extract §small-signal equivalent circuit parameters (ECPs),§improved by §modeling interaction between contact metalizations§and hybrid §optimization of T and Pi circuit topologies.§Excellent agreement §between measured and modeled S-parameters, with limited §deviation of optimized ECPs from their initial§values, is obtained up §to 40 GHz for a wide range of bias. Combined with NF50 §measurement, frequency- and bias-dependent noise§parameters §(NPs) up to 20 GHz are extracted using polynomial§approximation of §noise parameters for intrinsic device. Facilitated by§the correction of§source mismatch in measurement, great agreement between §measured and modeled NF50, as well as acceptably§deviated §optimized fitting factors, results in a minimum NFmin§of 1.64 dB at §10 GHz for an InGaP/GaAs HBT with two 2.3 by 5.6 um2§emitters. §Study of geometry-dependent performance shows promise§of high-§speed and low noise InGaP/GaAs HBTs using narrow,§long, and at §least two-sided base contacts.