Patent ID: 9564777
Date: 2017-02-07
CPC Classifications: A61B,A61M,A61N,H02J

Claim:
1. A system comprising: an implantable stimulation device; a midfield powering system wirelessly coupled to the implantable stimulation device, the midfield powering system including: a radio configured to transmit and receive microwave signals; a midfield coupler electrically coupled to the radio, the midfield coupler configured to convert signals from the radio to signals with a non-negligible H-field component parallel to a surface of the midfield coupler and focus the signals to a location in tissue associated with the implantable stimulation device that is within a wavelength of the microwave signals as measured in air; an amplitude detector electrically coupled to the midfield coupler, the amplitude detector configured to determine an amplitude of a signal transmitted by the implantable stimulation device and received at the midfield coupler; a variable gain amplifier electrically coupled between the radio and the midfield coupler, the variable gain amplifier configured to amplify a transmit signal from the radio in proportion to the amplitude determined by the amplitude detector, the transmit signal received by the implantable stimulation device; and a phase matching network comprising a phase detector and a phase shifter, the phase shifter and the phase detector electrically coupled to the midfield coupler, the phase detector configured to determine a phase of a signal transmitted by the implantable stimulation device and received at the midfield coupler and the phase shifter configured to adjust a phase of a signal provided to the midfield coupler based on the determined phase.