Load modulation detector

A method comprising:

• wirelessly transmitting power through tissue to an implant on or within a recipient's body by providing electrical current to power transmission circuitry inductively coupled to power reception circuitry of the implant;
• receiving a voltage indicative of variations imparted onto the electrical current by controlled adjustments of a resonant frequency and/or a resistive load of the power receiving circuitry;
• and
• detecting the variations on the electrical current, said detecting comprising:
• in response to the voltage, generating signals indicative of negative current variations and/or positive current variations on the electrical current;
• and
• deriving data from the signals.

An apparatus comprising:

• at least one coil driver comprising at least one current sense resistor;
• at least one power transmitting coil configured to receive an electrical current from the at least one sense resistor, the at least one power transmitting coil configured to be in inductive communication with a device;
• and
• load modulation sensing circuitry configured to detect variations of a voltage across the at least one current sense resistor.