A charger including a class E power driver, a frequency-shift keying ("FSK")module, and a processor. The processor can receive data relating to theoperation of the classE power driver and can control the class E power driver based on the receiveddata relating tothe operation of the class E power driver. The processor can additionallycontrol the FSKmodule to modulate the natural frequency of the class E power transformer tothereby allowthe simultaneous recharging of an implantable device and the transmission ofdata to theimplantable device. The processor can additionally compensate for propagationdelays byadjusting switching times.