A method of wireless power transfer includes providing a primary rail voltage to a primary coil via a primary transistor network, driving the primary transistor network with a primary PWM signal, inducing a secondary current on a secondary coil, providing a secondary rail voltage to a load via a secondary transistor network, generating a voltage signal from the secondary current via a current sense amplifier, phase-locking the voltage signal to the secondary current, adjusting a phase shift and amplitude of the voltage signal based on the impedance of the load, thereby generating a driving voltage, converting the driving voltage to a secondary PWM signal, and driving the secondary transistor network with the PWM signal.