Monte Carlo Investigation of Traveling Accumulation Layers in InP Heterojunction Bipolar Transistor Power Amplifiers

Abstract

We report Monte Carlo simulation results of 300nm InP heterojunction bipolar transistors driven to exhibit distortion. IM3 distortion is typically explained by collector velocity modulation. Full-band ensemble Monte Carlo simulations implicate intervalley transfer as an additional source of distortion under conditions of high current, low voltage, and high doping. Simulations reveal that intervalley transfer promotes the formation of traveling accumulation domains which result in high frequency distortion more significant than that caused by velocity modulation. Special care must be taken when designing high current HBT power amplifiers in order to mitigate this effect.