SC-Gate Technology for W-Band Amplifier Applications

A novel gain and maximum oscillation frequency (fmax) enhancement method for GaN high-electron-mobility transistors (HEMTs) was developed using a standing wave-controlled gate (SC-gate). By intentionally modifying the fingertip termination condition, drastic gain and fmax improvements were achieved in the millimeter-wave frequency band without changing the manufacturing process of the GaN HEMTs. This study reviews the SC-gate technology and previous prototype evaluation results and reports additional analysis results. Furthermore, a W-band amplifier, MMIC, was designed and fabricated based on the S-parameter measurement data of the SC-gate GaN HEMT. The maximum available gain (MAG) of the SC-gate GaN HEMT used in this amplifier MMIC was 10 dB at 80 GHz, whereas the MAG in a conventional GaN HEMT without an SC-gate was 4.5 dB. The maximum gain of the fabricated amplifier MMIC was 6.3 dB at 80.6 GHz. This value is higher than that of the conventional GaN HEMT, which confirms the effectiveness of the SC-gate technology in the W band.