190-GHz G-band GaN amplifier MMICs with 40 GHz of bandwidth

We report on three state-of-the-art G-band (140-220 GHz) GaN amplifier MMICs. A 4-stage common-source amplifier can provide a small-signal gain of 10 dB at 190 GHz with a 3-dB bandwidth of 40GHz (156-196 GHz). A 5-stage common-source MMIC achieves up to 12 dB gain at 190 GHz with a 36-GHz (157-193 GHz) bandwidth. Additionally, a 2-stage amplifier using inductive degeneration shows 6.3dB of gain at 179 GHz with a bandwidth of 12GHz (172-184 GHz). At 190 GHz, the 5-stage amplifier can deliver 14.1 dBm (279mW/mm) of output power at the 1.8-dB gain-compression point with a corresponding power-added efficiency of 1.2 %. To the best of our knowledge, these amplifiers show the highest gain above 170GHz among any reported GaN-based MMICs. This is also the first demonstration of multi-stage GaN circuits that can provide gain up to the 200-GHz mark.