A 3.3–4.3-GHz High-Efficiency Broadband Doherty Power Amplifier

Abstract

In this letter, the design of a broadband high-efficiency Doherty power amplifier (DPA) with a bandwidth of 1000 MHz for the 5G frequency band is proposed. The postmatching structure is employed to achieve broadband performance. The proposed DPA shows high efficiency at 6-dB output power back-off (OBO) in the entire 1000-MHz band. The DPA has been designed and implemented using commercial GaN HEMTs to validate the high efficiency and broadband characteristics. The fabricated DPA attains a measured 7.1-11.1-dB saturated gain and a 43.2-44.5-dBm saturated power. The 46%-52% and 58.6%-68.9% drain efficiencies are obtained at 6-dB OBO and saturation throughout the design band, respectively. A 20-MHz LTE modulated signal with a peak-to-average power ratio of 7.2 dB is also applied to the proposed DPA at 3.5 GHz. The average output power is 37.2 dBm. The measured ACPR is improved from -27 to -48.9 dBc with digital predistortion (DPD) performed.