A Waveform-Engineered Outphasing RFPA Using a Broadband Balun Combiner
This paper discusses advantages and benefits of using a broadband balun as a power combiner in a Chireix outphasing system. The balun operates over an extended octave bandwidth, which allows load modulation to be proscribed at fundamental and second harmonic frequencies, allowing continuous modes such as Class B-J to be implemented. The desired harmonic load termination is achieved without any specialized matching networks, and solely by means of load modulation provided by the active device interaction. Simulation results are verified and demonstrated; drain efficiencies of more than 65% and 50% are maintained over 6dB and 9dB output power ranges respectively, with signals operating at 1.95 GHz, while reaching a maximum combined power of 44.8 dBm.