An effective device design for thermal management of multifinger InGaP/GaAs collector‐up HBTs

Abstract

SUMMARYAn effective device structure for thermal management of multifinger InGaP/GaAs collector-up heterojunction bipolar transistors (HBTs), compelling active components in high-efficiency handset power amplifiers, is presented for the first time. From the unique 3-D thickness-adjusting numerical analysis, based on a finite element model, the miniaturized device can lead to a greater than 40% reduction in the thickness of plated gold layer. Above all, this is quite different from previous attempts, in which the thermal resistance was reduced by increasing the thickness of plated gold layer. Compared with literature works, the thermally stable design with an innovative heat-spread configuration shows a 50% reduction in thermal resistance and demonstrates favorable power performance.

Accurate and efficient analysis of the upward heat flow in InGaP/GaAs HBTs through an automated FEM‐based tool and Design of Experiments

“…Pervasive examples are the collapse of current gain affecting multi‐finger GaAs HBTs, which can be SOA‐limiting or even destructive, the discrepancy between dynamic and static error vector magnitude, thermal memory effects, and reliability/ruggedness issues in GaAs HBT PAs. Since the late 80s a plethora of papers have been published, which deal with the thermal or ET behavior of single‐ and multi‐finger transistors as well as of circuits in GaAs technology (representative ones being). Many studies focused on the metallization due to the important role played by the upward heat flow in this technology (the low thermal conductivity of the GaAs substrate mitigates the downward flow to the backside).…”