An X-band 35-dBm Compact Continuous-Mode Class-J Power Amplifier in 0.25-μm GaN Process

This paper presents an X-band 35-dBm continuous-mode class-J power amplifier (PA) implemented using 0.25-μm GaN process, featuring a compact chip size of 2.5 mm² and exceptional performance characteristics. The proposed PA leverages the benefits of the class-J topology to achieve significant bandwidth enhancement and efficiency improvement by optimizing fundamental and second harmonic impedances. Notably, this work addresses the challenges associated with operating the class-J topology at high frequencies. The continuous-mode class-J output matching approach is also explored in detail, along with several innovative matching methodologies. The proposed PA exhibits a 25.2% fractional bandwidth from 8.65 to 11.14 GHz, a gain of 24 dB, a peak power added efficiency of 37%. Compared to the prior art in GaN technologies, this work achieves the best figure-of-merits. The proposed PA demonstrates superior performances, making it an attractive candidate for high-power and broadband applications in the high frequency applications, such as 5G FR3 bands.