Generation 2 High Voltage Heterojunction Bipolar Transistor technology for high efficiency base station power amplifiers

A new generation of High Voltage Heterojunction Bipolar Transistor (HVHBT) technology was developed for base station high power amplifiers and multi-stage driver amplifiers. This is an improved version of previously reported InGaP/GaAs HBT capable of operating with supply voltages up to 32 V. Generation 2 HVHBT technology maintains the same high level of efficiency and compatibility with Digital Pre-Distortion (DPD) techniques but has higher gain, higher power density and greater tolerance to load mismatch and input overdrive. Two discrete power transistors, 120 W and 220 W, were developed using Generation 2 HVHBT technology for 2.1 GHz WCDMA/LTE applications. Both 2x120 W and 2x220 W Doherty amplifiers were designed to demonstrate gain approaching 14 dB and efficiency in excess of 55% at 6 dB operating back-off.