Abstract
This paper presents the design, fabrication, and experimental validation of a high-efficiency, high-linearity solid-state power amplifier (SSPA) operating across the X-band (8.5–10.5 GHz) for active electronically scanned array (AESA) radar systems. The amplifier employs a 0.25 µm gallium nitride on silicon carbide (GaN-on-SiC) high electron mobility transistor (HEMT). To address the fundamental trade-off between power-added efficiency (PAE) and linearity, a multi-harmonic load-pull continuous Class-F matching network was synthesized, suppressing harmonic generation while maintaining waveform shaping across a fractional bandwidth exceeding 20%. Low-frequency decoupling networks were integrated into the gate and drain bias paths to mitigate nonlinear memory effects and preserve spectral purity under high-power conditions. Measured results under continuous-wave and pulsed RF excitation demonstrate a saturated output power ($P_{\text{sat}}$) of 42.1 dBm (16.2 W) with a peak PAE of 51.4% and an average small-signal gain of 12.8 dB across the 8.5–10.5 GHz band. Two-tone linearity characterization with 10 MHz spacing revealed a third-order intermodulation distortion (IMD3) better than -32 dBc at 3 dB output back-off without external digital predistortion. The proposed GaN-on-SiC SSPA demonstrates exceptional thermal stability and pulse fidelity, offering an attractive solution for modern high-resolution radar transceivers.
