Sequential Load-Modulated Balanced Amplifier With Asymmetrical Output Coupling for a Load Modulation Continuum

The purpose of this article is to present a novel technique for sequential load modulation balanced amplifier (SLMBA) that is capable of achieving a continuum of load modulation (LM) ratio as well as high efficiency. By contrast with reported approaches that utilize asymmetric output couplers or asymmetric auxiliary devices to facilitate continuum LM ratios, which result in significant energy dissipation which negatively impacts performance, the proposed approach can significantly mitigate this issue. An output matching network is employed in this study to match the output of the balanced amplifier (BA) to the modified output coupler, so as to reduce energy consumption and improve performance by aligning the continuum of LM ratio with the optimal LM impedance. Based on the proposed theory, an RF-input SLMBA has been designed, implemented, and measured. Consequently, it achieves a saturation drain efficiency (DE) of 56.1%–64.7%, a saturation output power of 42.3–43.7 dBm at frequencies between 2.4 and 3.4 GHz, and a DE of 49.1%–58.9% in the 10-dB output back-off (OBO) state. It also exhibited 47.8%–53.11% average DE and 32.1–33.2-dBm average output power over 2.4–3.4 GHz when excited by a 20-MHz new radio (NR) signal with a 10-dB peak-to-average power ratio (PAPR). After digital predisposition (DPD), it achieved an adjacent channel power ratio (ACPR) better than −49.1 dBc.