A Compact and Broadband Ka-Band Asymmetrical GaAs Doherty Power Amplifier MMIC for 5G Communications
In this paper, we present a compact and broadband Ka-band asymmetrical Doherty power amplifier (DPA) MMIC in a 0.15-µm enhancement mode (E-mode) GaAs pHEMT process. The offset line behind the main power amplifier is removed without degrading the back-off efficiency by choosing an appropriate output matching network and employing a design method based on load-pull data, which results in a compact chip size of 2.1 mm × 1.7 mm, and a broad bandwidth (BW) of 2.8 GHz, simultaneously. Experimental results demonstrate that the DPA achieves a saturation output power of 26.3 dBm, with a power added efficiency (PAE) of 35% at saturation and 28% at 7 dB power back-off (PBO) at the frequency of 31.1 GHz. The DPA also achieves a saturation output power of 25.7 dBm – 26.8 dBm, a peak PAE of 31%–38%, and a PAE at 7 dB PBO of 21%–30% in the frequency range of 29 GHz to 31.8 GHz.