Reactive nonlinearity for low power rectification

Terrestrial applications of microwave power transmission (MPT) such as RFID is highly challenging. As the distance between energy transmitter and receiving circuit increases, the available received power ramps down, thus causing an abrupt drop in RF/DC conversion circuit. Numerous works have been reported recently, but resulting in very incremental improvements over the state of the art. This paper proposes an original concept that is quite different from the current mainstream rectifier design. Instead of developing rectifier using a nonlinear resistance (diode), it is proposed to design the circuit with a nonlinear reactance. A theoretical foundation is provided, showing the loss limitation of diode-based rectifier circuits as well as the superiority of the proposed new concept at low power. Finally, an evaluation of efficiency for a practical RF-DC conversion at 2.45GHz is discussed.