Compact Ka-Band GaN Doherty Amplifier with Optimized Output Matching

This paper proposes a compact Ka-band GaN Doherty power amplifier structure. Miniaturization is achieved by sharing the DC supply between the main and peak amplifiers and integrating the power delivery path into the impedance transformation network, thereby reducing the size of the output matching circuit. The amplifier was designed and fabricated using a 0.15 μm GaN-on-SiC process, resulting in a chip size of 1.5×1.1 mm. Measurements show that the amplifier achieves a saturated output power (Psat) of 30.8~31.8 dBm and a power-added efficiency (PAE) of 30~34 % across the 26.0~27.5 GHz frequency range. Under a 6 dB output back-off condition, the PAE remains between 24~27 %.