A charger including a class E power driver, a frequency-shift keying (“FSK”) module, and a processor. The processor can receive data relating to the operation of the class E power driver and can control the class E power driver based on the received data relating to the operation of the class E power driver. The processor can additionally control the FSK module to modulate the natural frequency of the class E power transformer to thereby allow the simultaneous recharging of an implantable device and the transmission of data to the implantable device. The processor can additionally compensate for propagation delays by adjusting switching times.