An implantable medical device has a hermetically sealed housing with at least one feedthrough therein for a conductive path between an RF antenna carried by the housing, and an RF telemetry circuit contained in the housing. The feedthrough has a feedthrough housing with a capacitor element therein having first and second capacitor plate configurations, with a first of the capacitor plate configurations being connected to the RF antenna and a second of the capacitor plate configurations being connected to the RF telemetry circuit. The feedthrough functions both as a hermetic seal and as a galvanic isolation for voltage protection of the components of the RF telemetry circuit, and other circuitry in the sealed housing connected thereto.