확장된 백오프 출력에서 고효율 동작을 위한 최적화된 대칭 이단 도허티 전력 증폭기 설계

Abstract

This article presents a symmetric two-stage Doherty power amplifier (DPA) for the extended output power back-off level, which can be attained even with a reduced circuit size by changing the output impedance of the peaking amplifier to be inductive without the offset line. The ABCD matrix is employed to design the output matching network of the peaking amplifier with a simple transmission line. Consequently, we can reduce the design complexity by applying the same circuit to the carrier amplifier as the DPA is symmetric. To deal with reduced output power of the class-C peaking amplifier, a two-stage DPA structure was applied. The power amplifier exhibited a drain efficiency (DE) of 63.5 %, and a power added efficiency (PAE) of 50.6 % at 7.5 dB output backoff was obtained using the 3.5 GHz pulsed continuous wave (CW) signal. Furthermore, a DE of 53.3 %, a PAE of 43.2 % and a power gain of 18 dB were obtained at the power level of 41 dBm using a 20 MHz LTE signal with a peak-to-average power ratio of 7.5 dB.