A 0.03–6-GHz Mode-Decoupled GaN Power Amplifier With Frequency-Segmented Efficiency Enhancement

This article presents a spectrally agile gallium nitride (GaN) power amplifier (PA) targeting multifunction RF systems. To resolve the inherent tradeoff between instantaneous ultra-wideband (UWB) coverage and high-efficiency frequency agility, a mode-decoupled design methodology is proposed. Built upon a distributed topology, the architecture features a reconfigurable gate artificial transmission line (ATL) that isolates the narrowband (NB) design constraints from the wideband baseline. Within this decoupled framework, an embedded inverse-gain-roll-off wideband continuous reconfigurable network (WCRN) is integrated with a resonance-based frequency-segmented efficiency strategy. This configuration enables continuous frequency tuning from 2.3 to 6 GHz while simultaneously optimizing efficiency across the segmented subbands. The PA supports four modes: 0.03–6-GHz UWB, sub-3 GHz UWB with harmonic suppression, continuously tunable single-NB (SNB), and concurrent dual-NB (DNB). In the 0.03–6-GHz UWB mode, measurements demonstrate 40.2–43.0 dBm saturated power and 14–17-dB power gain with a baseline power-added efficiency (PAE) exceeding 41%. Notably, enabling the NB modes yields a maximum efficiency enhancement of 13% over the UWB baseline, reaching 55% peak PAE in the 4–6-GHz band. Linearity is verified with a representative 20-MHz 64-QAM signal at 2.4/5.6 GHz, achieving −25.6/−23.3-dB error vector magnitude (EVM) at 35.1/34.6-dBm average power. This work provides a versatile hardware solution for future software-defined platforms.