Boosting the thermal stability of paralleled GaAs HBTs through temperature-dependent ballasting resistors: A proof-of-concept study

This paper explores the efficacy of base ballasting strategies in enhancing the electrothermal (ET) stability of paralleled InGaP/GaAs heterojunction bipolar transistors (HBTs) for radiofrequency (RF) applications. More specifically, technologically-feasible temperature-dependent base ballasting resistors are proposed as a solution to shift the collapse of current gain to higher power densities. A three-cell test device fabricated through a state-of-the-art process is considered as a simple case study. Extremely accurate DC and AC ET simulations are performed with SPICE to quantify the advantages of the proposed strategy with respect to traditional approaches.