Parameter extraction for HBT's temperature dependent large signal equivalent circuit model [MMIC oscillator]

Abstract

An eleven node large signal heterojunction bipolar transistors (HBT) model in hybrid-/spl pi/ configuration is investigated which is derived from HBT topology. This is the first circuit simulation model where the temperature is introduced as a variable simulation parameter using the concept of thermal resistance and pseudotemperature to account for the temperature dependent thermal conductivity of GaAs. The temperature and bias dependence of key model parameters -thermal resistance, transit time, emitter resistance, base-emitter and base-collector junction parameters- are extracted analytically from measured DC and S-parameter data in the temperature range from 20 to 160/spl deg/C using on wafer thermochuck measurements. The devices have f/sub t/ and f/sub max/ values of 40 GHz each. The verification of the proposed model is carried out on a simple oscillator circuit at 4.7 GHz, where the temperature dependence of oscillation frequency and output power of the first three harmonics is compared to measured data.<>