A transmitter circuit in a wireless power transmission system has a tank circuit, having an inductor and a capacitor, the inductor being couplable to the inductor of a receiver circuit. An oscillator generates an oscillation frequency signal for driving the tank circuit. A first digital-to-analog converter (DAC) provides a first control signal to control the oscillating frequency of the oscillator. A frequency shift keying (FSK) circuit changes a digital signal input to the digital-to-analog converter for shifting the oscillation frequency utilized to drive the tank circuit, the FSK signal transmitting data or commands to the receiver circuit. A method of transmitting FSK signals in a wireless power transmission system is also disclosed.