Abstract
This letter presents a dual-band (0.902 and 2.45 GHz) radio frequency (RF)-dc CMOS converter employing the internal threshold voltage cancelation (IVC) technique to harvest electromagnetic energy. The realized RF-dc CMOS converter maintains high power conversion efficiency (PCE) by passively reducing the threshold voltage of the forward-biased transistors so as to increase the harvested power, and increases the threshold voltage of the reverse-biased transistors to reduce the leakage current. More than 20% measured PCE is achieved at 0.902 GHz from -9 to 10-dBm input power range and a peak PCE of 47% is obtained at 1 dBm. At 2.45-GHz band, more than 11% measured PCE is achieved from -2 to 15 dBm input power range and a peak PCE of 27.1% is obtained at 6 dBm. A single-stage RF-dc CMOS converter is realized in 180-nm CMOS technology and it can serve as a good reference to multiband CMOS energy harvesting design in the future.