An efficient thermal-removal design of GaAs/InGaAs/InGaP HBT-based power amplifiers

To lessen mutual-thermal-coupling effects, both n-p-n and p-n-p GaAs/InGaAs/InGaP collector-up heterojunction bipolar transistors (HBTs) with an efficient thermal-removal design (TRD), which can be used in power-amplifier circuits for the next-generation renewable-energy system, have been presented in this report. Notably, different from lately proposed thermal-properties-enhancing collector-up structures and thermal-via-hole configurations, the TRD-implemented multi-finger devices, with a graded InGaAs base but without the conventional collector conformation, are demonstrated to achieve compelling heat-removing thermal performance. Preliminary results show that the thermal coupling has been substantially decreased, and nearly 20% improvement, compared to previous work, in the surface temperature-rise ratio is obtained. Unprecedentedly, the TRD has a stronger influence on the p-n-p device than on the n-p-n device based on the pragmatic observations.