Design of G-Band Watt-Level GaN Power Amplifier With Multiband Large-Signal Impedance Correction and Circuit-Package Co-Design Technique Weibo Wang, Zhe Li, Kai Li , Haifeng Cheng , Fangjin Guo

Abstract

This article presents a gallium nitride (GaN) solid- state power amplifier (SSPA) operating in the G band and delivering watt-level output power. To enhance the performance of the 2 × 20 µm GaN high electron mobility transistors (GaN HEMTs), AlN /GaN heterojunction, n + GaN regrown, and 50-nm floating T-gate are employed with a transconductance of 880 mS /mm and an f T ( f max) of 180 GHz (420 GHz). By utilizing multiband large-signal impedance correction technology, the optimal power matching impedance for GaN HEMTs was achieved without the need for a G-band load–pull testing system. As a result, a 50-nm GaN power amplifier monolithic microwave integrated circuit (PA MMIC) is designed with an output power of 100 mW at 216 GHz and a power density exceeding 1.35 W /mm at 216 GHz. The measured power-added e fficiency (PAE) exceeds 2% across the entire frequency band. Further- more, the circuit-package co-design technique integrates bonding wires, waveguide-to-microstrip transitions, and the packaging cavity into the matching networks of PA MMIC. It minimizes output power and bandwidth degradation due to the packaging parasitics. The presented SSPA module employs 32-way GaN PA MMICs with power combining and delivers >1-W saturated output power across 216–226 GHz, peaking at 1.54 W at 223 GHz. The power gain exceeds 9 dB and reaches 10.1 dB at 223 GHz. The maximum combining e fficiency is 48.7%.