Dual-Band Dual-Output Four-Way Doherty Power Amplifier for Unsynchronized Time-Division Duplexing

Abstract

This article proposes a dual-input dual-output dual-band four-way Doherty power amplifier (DPA) architecture, capable of linearized operation at one frequency band without being disturbed by arbitrary load switching at the other frequency band. The proposed technique is demonstrated through the design, implementation, and measurement of a prototype circuit operating at 1.85-and 2.65-GHz bands with 70-MHz bandwidth for each band. The prototype dual-band DPA (DB-DPA) achieves a peak output power of 49.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 0.2 dBm for the 1.85-GHz band and 49.3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 0.5 dBm for the 2.65-GHz band. Furthermore, the measured drain efficiency at 9-dB power back-off (PBO) is 59%–64% and 60%–65% for the 1.85-and 2.65-GHz bands, respectively. Concurrent dual-band performance, dynamic power sharing capability, and utility of the proposed DB-DPA in unsynchronized time-division duplexing (TDD) applications are demonstrated by using 20-MHz new radio (NR) signals with 9-dB peak-to-average power ratio (PAPR). For an average output power of 39 dBm per band, the concurrent dual-band measurement yields 49% average drain efficiency and better than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 48-dBc adjacent channel leakage ratio (ACLR).