A 2-stage, 50Ω RF-DC Charge-pump with Load Lines for high RF-DC Voltage Conversion

A novel 2-stage RF-DC charge-pump circuit (RFCP) with a 50 ohm input impedance and higher RF-DC voltage conversion without an external input-matching network or output DC-filter for ambient wireless energy-harvesting (WEH) in the 2.4 GHz band is presented. The novelty of this RFCP is the use of near quarter-wavelength transmission lines on the load-side of each half-wave rectifying stage in the RFCP to induce a standing wave maxima at each of the diode inputs at 2.4 GHz. Doing so minimizes diode losses and maximize RF-DC voltage conversion of the charge-pump while still achieving a near 50 ohm input impedance. Simulations and measurements show the proposed design generating a higher DC output of 2.12V and energy efficiency of 18% with just -6dBm of RF input; an RF sensitivity of -7.2dBm for 1.8V output; and a 50Ω input impedance (reflection coefficient = -11dB) in the 2.4 GHz band.