A 30 nm gate length InGaAs channel MOSFET MMIC technology is presented. 100 mm semi-insulating GaAs substrates with a metamorphicaly grown InGaAs/InAlAs device heterostructure are used. Al2O3 is deposited as gate dielectric onto the In08Ga02As channel by atomic layer deposition. The gate layout was optimized for monolithic microwave integrated circuit (MMIC) applications using T-gates and wet chemical recess etching to minimize the parasitic gate capacitances. For a 2 × 20 μm gate width transistor a transit frequency fT of 306 GHz and a maximum oscillation frequency fmax of 381 GHz was extrapolated, respectively. This technology was employed for the fabrication of a 230-275 GHz amplifier MMIC with 4 cascode stages achieving a small signal gain of 12 dB at 250 GHz. To the best of the authors knowledge, this is the first reported InGaAs MOSFET millimeter-wave amplifier MMIC operated in the frequency regime beyond W-band.