Small-Signal Modeling and Microwave Noise Characterization of InGaP/GaAs HBTs

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 ? 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.