High efficiency microwave power amplifier with peak power injection

摘要

In order to amplify OFDM or multi-code CDMA modulation signals, which have large peak power to average power ratio (PAR), microwave amplifiers should be operated at large backoff. It is very important item to improve the amplifier's efficiency at large backoff. To enhance efficiency at large backoff operation, Peak Power Injection Amplifier (PPIA) is proposed. The PPIA is consists of class-AB and class-C amplifiers and circulator. The circulator is located at output-port of the class-AB amplifier. When instantaneous power of modulation signal is large, the RF power is injected from the class-C amplifier to the output of the class-AB amplifier though the circulator, in order to modulate load impedance of the class-AB amplifier. Experiment at 2GHz shows efficiency enhancements.