Compact Asymmetrical Quasi-MMIC Doherty Power Amplifier

Abstract

This paper presents a compact asymmetrical Doherty power amplifier (PA) based on a quasi-MMIC configuration for 5G sub-6 GHz applications. The proposed Doherty PA is composed of commercial GaN HEMTs and several passive components implemented on a silicon (Si) substrate. In order to achieve size and cost advantages, passive components such as a power divider, input matching networks, output matching networks, and a Doherty combiner are realized using Si-integrated passive device (Si-IPD) technology, which costs about 40% of the budget for the entire GaN MMIC process. For the 3.5 GHz pulsed-continuous waveform signal, the fabricated Doherty PA has an efficiency of 52.6% at a saturated output power of 44.2 dBm. Furthermore, an efficiency of 45.6% was achieved with the output power back-off (OBO) of 7.0 dB. The implemented PA occupies only 8.9 mm × 5.6 mm.