A novel load insensitive RF power amplifier using a load mismatch detection and curing technique

This paper proposes a new load insensitive RF power amplifier (PA) for mobile handsets using a load mismatch detection and curing technique. The PA controls a tunable output matching network (TOMN) adaptively based on the information of a mismatched load, thereby enhancing PA performances dramatically at a mismatched load without substantial performance degradation at a matched load. A load mismatch detector and TOMN can simply be implemented by using 0.18-μm silicon on insulator (SOI) FET that are integrated with 2-μm InGaP/GaAs HBT PA MMIC into a single module. To verify the idea, the PA module has been designed and implemented especially for a linearity enhancement under load mismatch condition. With WCDMA R'99 signal at 1.95 GHz, the measured results showed that ACLR at output power of 28.25 dBm was improved by as much as 13.7 dB on the worst ACLR-load angle compared to a conventional PA. In this way, the proposed load insensitive PA can keep ACLR under -37 dBc all over the load angle at 2.5:1 voltage standing wave ratio (VSWR).