The InO.53Ga0.47As-based planar-type junctionless fieled-effect transistor (JLFET) and fin-type FET (FinFET) have been designed and characterized by technology computer-aided design (TCAD) simulations. Because of their attractive material characteristics, the combination of In0.53Ga0.47As and InP has been adopted in some of the most recent semiconductor devices. In particular, the In0.53Ga0.47As-based transistor using an InP buffer is highly attractive due to its superior electrostatic performance which results from the by particular characteristics of the In0.53Ga0.47As material. In this paper, we focus on using small-signal RF modeling and Y-parameter extraction methods th extract various RF characteristics, such as gate capacitance, transconductance (gm), cut-off frequency (fT), and maximum oscillation frequency (fmax). The proposed InO.53Ga0.47As-based FinFET exhibits an on-state current (Ion) of 1030 μA/μm and an off-state current (Ioff) of 1.2 x 10(-13) A/μm with a threshold voltage (Vth) of 0.1 V, and a subthreshold swing (S) of 96 mV/dec. In addition, fT and fmax are determined to be 243 GHz and 1.6 THz, respectively.