Highly Robust GaN Power Amplifier at Millimeter-Wave Frequencies Using Sputtered Iridium Gate MMIC Technology

This article presents the application of FBH’s sputtered Iridium (Ir) gate technology for the design and realization of a highly robust power amplifier (PA) intended for satellite communication systems at millimeter-wave frequencies. Implemented in the 0.15-
$\mu \text{m}$
Gallium nitride (GaN)-on-SiC high-electron mobility transistor (HEMT) technology, the PA delivers a reasonable gain of 14.3 dB, a 1-dB compression output power (
${P} _{\text {1 dB}}$
) of 21.7 dBm, and a maximum power-added-efficiency (PAE) of 19.7% at 38 GHz. For assessing the circuit-level robustness, a high-level RF stress has been performed at an elevated ambient temperature of 200 °C. After being stressed at 22 dBm input level (corresponding to 6-dB gain compression output power level) for 10 h, the PA showed less than 0.5 dB degradation in the saturated output power (
${P} _{\text {sat}}$
). Compared to the benchmark monolithic microwave integrated circuit (MMIC) chip fabricated with Pt-evaporated gate, the Ir-sputtered technology demonstrated much less degradation in terms of the total drain current, output power, and PAE after stress. The superior performance has demonstrated the great potential of this technology for highly robust applications at millimeter-wave frequencies.