A Distinctive Parallel R–C Matching Technique for Nonlinearity Reduction in GaN MMIC PA for FMCW Radar Applications

ABSTRACT Gallium nitride (GaN) high electron mobility transistors (HEMTs) inherently demonstrate nonlinear behavior due to input capacitance modulation and bias‐dependent variations at elevated power levels, resulting in significant phase distortion and diminished intermodulation performance in power amplifiers (PAs). This paper presents a distinctive parallel R–C loaded matching technique aimed at mitigating these nonlinearities in GaN monolithic microwave integrated circuit (MMIC) PAs designed for frequency‐modulated continuous‐wave (FMCW) radar applications. The intrinsic device‐level sources of nonlinearity are examined, and the efficacy of the proposed network in suppressing amplitude‐phase (AM–PM) distortion and enhancing intermodulation distortion (IMD) characteristics is comprehensively assessed. Utilizing this technique, a 15–20 GHz three‐stage GaN MMIC PA is designed and simulated, achieving over 30 dB small‐signal gain, 23%–31% power‐added efficiency (PAE), and a peak power of 39.3 dBm at 17 GHz. The PA demonstrates excellent linearity, with AM–PM variation constrained within ±2° at saturation. The final design occupies a compact 3.37 × 2.59 mm 2 footprint, rendering it highly suitable for high‐throughput FMCW radar transmitters. Additionally, full electromagnetic (EM) co‐simulation, including quad flat no‐lead (QFN) packaging and bond‐wire parasitics, is conducted to validate performance robustness under practical integration constraints.