This paper presents a Cockcroft-Walton (CW) generator as a solution to generate an intermediate high voltage for the supply of a DEA cardiac assist device. This consists in fully passive converter allowing to output a DC signal from an alternative signal especially suitable for AC sources. Furthermore, implanted medical devices require a wireless power transfer system to provide energy inside the body without the need for wires through the skin. Thus, in this paper we propose to combine those two systems to optimize the efficiency and the size of the final system. In this work, the WPT consists in two coupled inductances of 6 cm diameter at a 2 cm distance from each other driven by a GaN half-bridge while The CW generator has 8 stages. The overall system can output 200 V at 1 W inside the body from a 20 V DC signal at the input and with an overall efficiency of 79 %.