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).