A 30-W GaN Quasi-MMIC Doherty Power Amplifier Based on All-Distributed Inductors Load Network

This paper presents a high-power quasi-monolithic microwave integrated circuit (q-MMIC) asymmetric Doherty power amplifier (DPA) by using load network with all-distributed inductors. By appropriately choosing the load resistance at the junction point and the topology of the load network, optimal load-modulation can be realized with all inductors in the load network using distributed inductors for achieving greater power capacity and lower device losses in a compact size. For verification, a 3.4-to-3.8-GHz q-MMIC DPA was designed and fabricated using a 0.25-um GaN-HEMT process and a high breakdown voltage GaAs-IPD process. Experimental results show that a saturated power of 44.4-45.1 dBm, a saturated drain efficiency (DE) of 60.4%-66.5%, and an 8-dB back-off DE of 45%-49% are achieved from 3.4 GHz to 3.8 GHz. For an 80-MHz modulated signal, a DE of 46.5% with good linearity after linearization is obtained at an average output power of 36.6 dBm.