A Novel Dual-Band Concurrent Asymmetric Doherty Power Amplifier for Wireless Communications

摘要

In this paper, a different dual-band asymmetric Doherty power amplifier (ADPA) with a novel dual-band bandpass filter (DBBPF) with quad-section stepped impedance resonators (SIRs) is presented. This specific DBBPF rejects the annoying frequencies of the second and third harmonics in the dual-band and contributes considerably to performance improvement of ADPA. This structure is confirmed with the design, simulation, implementation and testing of a 10 W GaN-based ADPA for global system for mobile communications (GSM) and worldwide interoperability for microwave access (WiMAX) applications at 1.84 and 3.5 GHz, respectively. In the measurement results, the ADPA defines a drain efficiency (DE) of 63.7% with an output power of 35 dBm and power gain is 14.2 dB, and a DE of 47.5% with an output power of 34.5 dBm and power gain is 10.4 dB at the 9 dB output power back-off (OBO) from the saturated output power in the two frequency bands. Linearity effects, applying 10 MHz 16 QAM signal and a 5 MHz WiMAX signal, display an adjacent channel leakage ratio of -48.9 and -47.3 dBc with the average output power of 36.8/36 dBm at 1.84/3.5 GHz, respectively.