A 18–24.5 GHz high-power-density GaN MMIC power amplifier with impedance-frequency-tracking-based wideband matching approach

This article proposes a novel broadband power amplifier (PA) design methodology based on a multi-stage configuration featuring frequency-tracking impedance matching and gain equalization through frequency-dependent load control. Specifically, a multi-stage PA architecture is introduced where the final stage implements frequency-following load impedance matching, while the driver stage employs frequency-variant load impedance to regulate gain-frequency characteristics, collectively enabling effective broadband operation. For validation, an 18–24.5 GHz broadband PA was fabricated using 0.15-$\mu m$ Gallium Nitride (GaN)-on-silicon carbide (SiC) high-electron-mobility transistor (HEMT) technology. Measurements demonstrate saturated output power of 31.5–32.5 dBm, power gain of 26.7–29 dB, and power-added efficiency (PAE) of 23.6–31.3% across the operating band. It means that a power density of 3.5–4.4 W/mm over a 30.5% fractional bandwidth is achieved and a possible design paradigm of broad PA for K-band broadband applications is given.