Patent ID: 7720547

Claim:
A medical apparatus comprising an extracorporeal power supply forming a wireless closed loop system with a medical device adapted for implantation into a patient, wherein: the medical device comprises a first receiver for a first wireless signal, a power circuit that extracts energy from the first wireless signal to power the medical device, and a feedback signal generator that transmits a second wireless signal having a frequency that varies to indicate an amount of energy extracted from the first wireless signal; and the extracorporeal power supply comprises a source of electrical power, a power transmitter that emits the first wireless signal, a second receiver for the second wireless signal, a feedback controller connected to the second receiver and the power transmitter to control transmission of the first wireless signal in response to frequency variation of the second wireless signal, the extracorporeal power supply further comprises a source of data specifying an operational parameter for the medical device and a data modulator coupled to the source of data and the power transmitter to modulate the first wireless signal in response to the data, wherein the first wireless signal comprises power pulses which vary in width in response to the second wireless signal, and each power pulse comprises a series of sub-pulses which encode data from the source of data; wherein the medical device further comprises a data detector for extracting the data from the first wireless signal.