GaN HEMT based MMIC design and fabrication for Ka-band applications

Abstract

Gallium Nitride (GaN) technology has recently dominated the high power applications in the mm-wave frequencies, and its commercial use is emerging with the upcoming 5G technology. High Electron Mobility Transistors (HEMTs) based on GaN show superior material properties and high power densities, which makes them promising candidates to utilize for Monolithic Microwave Integrated Circuits (MMICs) in high frequency applications. NANOTAM’s 0.15µm/0.2µm GaN HEMT on Silicon Carbide (SiC) microfabrication process is used to fabricate the transistors and passive components. Process steps are explained, as well as in-house epitaxial growth. Fabricated transistors are characterized for their direct current (DC), small-signal, and large-signal performances. T-gate structure of the transistors is optimized for the highest gain performance at 35GHz. A three-stage MMIC amplifier is designed, fabricated in two process cycles, and measurements are performed on-wafer at room temperature. The best performing MMIC shows a small-signal gain higher than 23.1dB with an output power of 31.9dBm and a power-added efficiency (PAE) of 26.5% at 35GHz.