5V E-Mode GaN-on-Si on GF's RFGaN-LV1 Set to Transform Handset RF Front-Ends

Before gallium arsenide (GaAs) HBTs rose to prominence in the late 1990s, mobile power amplifiers relied mainly on silicon bipolar junction transistors and early GaAs devices. The first generation of phones used silicon BJTs operating in the 450 to 900 MHz range. These worked well at higher supply voltages, roughly 4.8 to 6V, but struggled with power and efficiency as handsets shifted toward lower voltages of 3 to 3.6V. GaAs MESFETs offered better efficiency at 900 MHz but needed a negative gate voltage, which meant adding charge pumps that drove up cost, complexity, and board space. Silicon LDMOS, now mostly associated with base stations, also saw some early use in handsets. It was cheaper than GaAs and more rugged against antenna mismatch, but its larger die size for a given power level made it hard to fit into the increasingly compact flip-phone designs of the mid-90s.

GaAs HBT ultimately became the dominant technology of that era because it solved multiple problems at once: it ran on a single positive supply voltage rather than needing a negative rail, it packed more power density into a smaller footprint than LDMOS, and it performed efficiently at 3.2V, aligning well with the shift to lithium-ion batteries.