In this paper, 90-nm T-shaped gate InP-based In0.52Al0.48As/In0.65Ga0.35As pseudomorphic high electron mobility transistors (PHEMTs) with well-balanced cut-off frequency ft and maximum oscillation frequency fmax are reported. This device with a gate-width of 2×25 μm shows excellent DC characteristics, including a maximum saturation current density Idss of 894 mA/mm, and a maximum extrinsic transconductance gm,max of 1640 mS/mm. The off-state breakdown voltage (BVoff-state) defined at a gate current of 1mA/mm is 3.3 V. The RF measurement is carried out covering the full frequency range from 1 to 110 GHz, an extrapolated ft of 252 GHz and fmax of 394 GHz are obtained, respectively. These results are obtained by the combination of gate size scaling, parasitics reduction and the on-wafer measurement in the full frequency band from 1 to 110 GHz.