Switch-mode amplifier ICs with over 90% efficiency for Class-S PAs using GaAs-HBTs and GaN-HEMTs

This paper reports on design and realization of monolithic switch-mode amplifiers for data rates up to 1.8 Gbps, suitable for Class-S and inverse class-D PA modules. GaN HEMT as well as high-voltage GaAs-HBT technologies are employed and compared. For digital signal transmission without output filtering, the chips achieve efficiencies of more than 90% at an output power of 5.4 W and 6.5 W with PAE values including the on-chip drivers, of 75% and 80% for GaAs-HBT and GaN-HEMT Ics respectively. These high efficiencies values are very promising since such PA chips represent the key building block for future class S systems.