Abstract: The present invention provides a modulation circuit and a method for modulating a wireless power transfer circuit. The modulation circuit has a switching circuit having a first state and a second state. The modulation circuit also has a modulation mode in which the first state defines a normal state and the second state defines an operative state. In the operative state, the modulation circuit modulates an electrical parameter of the wireless power transfer circuit in a modulation direction. The modulation circuit is configured to apply a trial modulation to the electrical parameter to determine whether the modulation direction is in a desired modulation direction. The modulation circuit is also configured to apply a modulation translation if the modulation direction is not in the desired modulation direction, with the modulation translation changing the modulation mode such that the modulation direction is in the desired modulation direction.