Design and Measurement of GaN High Power Amplifier MMICs considering Gate Leakage Current

This paper presents design, development and characterization of GaN based high power amplifier Monolithic Microwave Integrated Circuits (MMICs) at C-band and Ka-band. The MMICs are designed using GaN MMIC processes from UMS foundry. The C-band MMIC is designed using space evaluated $0.25\mu\mathrm{m}$ Gallium Nitride (GaN) High Electron Mobility Transistors (HEMT) process and the Kaband MMIC is designed using $0.15\mu$ m GaN HEMT process which is under space evaluation. On-wafer measurements of both the MIMICs were carried out. The C-band MIMIC exhibits output power, Power Added Efficiency (PAE) and Gain better than $ 43\mathrm{dBm},$43% and 25dB respectively. At Ka-band output power, PAE and Gain better than $ 38\mathrm{dBm},$ 30% and 18dB are achieved respectively. The MMICs are tested in test modules exhibiting similar performances. The paper also discusses about observed drain current runaway phenomena in GaN amplifiers due to gate leakage current. Importance of gate series resistor value selection is discussed to avoid this runaway and to prevent eventual burn-out of the chip transistor.