Patent ID: 8228027

Claim:
An efficient power transmitter, comprising: an electronically-controlled switch controlled by a first pulse width modulation control circuit, said switch configured to pull current through a first inductor when said switch is closed, said first pulse width modulation control circuit outputting a PWM output signal to control said switch; a transmitting coil comprising a multilayer printed circuit disposed on a non-conductive substrate, wherein vias are disposed along a length of said transmitting coil to connect conductors on different layers, and wherein said vias are configured to reduce skin effect losses and proximity effect losses when said power transmitter is used to wirelessly transmit electric power to a receiver; a first feedback signal obtained from a control input of said switch; and a second feedback signal obtained from a terminal of said inductor, wherein a control feedback signal is determined, at least in part, as a difference between said first feedback signal and said second feedback signal is provided to said first pulse width modulation control circuit, said control circuit adjusting a frequency of said PWM output signal, at least in part, in response to said control feedback.