Vertical III-V nanowire MOSFETs show potential towards the ultimate transistor scaling. A high transconductance and current density are achieved based on the gate-all-around architecture. This work presents a high-frequency design of such devices, achieving more than 600 GHz cut-off frequencies (fT, fmax), at 20 nm gate length. Furthermore, capacitance design and scaling trends, supported by COMSOL Multiphysics simulations derive state-of-the-art parasitics magnitudes for vertical devices in general, reaching gate-drain capacitance values of 17 aF/wire, corresponding to 0.2 fF/m. A unique co-designed feedback resonant circuit makes the device unilateral, exhibiting up to 15 dB gain in D-band at 0.5 V supply, and with a current density of 0....