Broadband, wide efficiency range, Doherty Amplifier design using frequency-varying Complex Combining Load

This paper presents a novel technique to extend the bandwidth and efficiency range of Doherty Power Amplifier (DPA) by the adoption of frequency-varying Complex Combining Load (CCL) and proper input current control strategy. For verification, a 42 dBm, 1.8-2.2 GHz DPA with OBO of 9 dB was designed, built and characterized. Under Continuous Wave (CW) stimulation, a back-off efficiency (8.5 dB) of 55-59% and saturation efficiency of 69-73% were observed over the entire bandwidth. With single carrier WCDMA signal excitation (PAPR of 9.3 dB), an average drain efficiency of 53-58% was obtained at 33.5 dBm average output power and Adjacent Channel Leakage Power (ACLR) of around -30 dBc.