Symmetrical Load Modulated Balanced Power Amplifier With Asymmetrical Output Coupling for Load Modulation Continuum
Paul Saad, Rui Hou
Abstract
This article presents a technique for load-modulated balanced amplifiers (LMBAs) to achieve a continuum of load modulation (LM) ratio. This has been possible in prior arts using asymmetrical auxiliary devices. In contrast, the proposed technique employs identical auxiliary devices. A LM ratio is enabled by a specific coupling factor of the power-combining coupler at the output. The proposed LMBA technique is demonstrated through the design, implementation, and measurement of a concurrent wideband LMBA operating across 3.1–4.2 GHz. The prototype achieves a peak output power of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ 48.1\pm 0.6~\text {dBm}$ </tex-math></inline-formula> , with drain efficiency of 47–58% at peak power and 47–61% at 10-dB power back-off. The concurrent wideband performance is demonstrated by a characterization with 900-MHz new radio (NR) signal with 10-dB peak-to-average power ratio (PAPR). At 37.8 dBm of average output power, the measurement yields 44% drain efficiency and −44-dBc adjacent channel leakage ratio (ACLR).