MIDFIELD POWER SOURCE FOR WIRELESS IMPLANTED DEVICES

Systems, devices, and methods discussed herein include wireless midfield transmitters and implantable receiver devices. A midfield transmitter can be configured to provide signals outside of tissue that give rise to propagating signals inside of tissue. The present subject matter includes a protection circuit for a transmitter device, a layered transmitter device, an implantable receiver device, implantation and extraction methods, test and assembly methods, and the like. In an example, a protection circuit includes a first control circuit to receive an RF drive signal and conditionally provide an output signal to an antenna. A second control circuit can generate a control signal based on the antenna output signal and/or information about the RF drive signal. A gain circuit can provide the RF drive signal to the first control circuit. The gain circuit can change an amplitude of the RF drive signal based on the control signal from the second control circuit.