Near zero turn-on voltage high-efficiency UHF RFID rectifier in silicon-on-sapphire CMOS

A UHF RFID rectifier which turns on at near zero input voltage is demonstrated. The rectifier is fabricated in 0.25-µm silicon-on-sapphire (SOS) CMOS technology using intrinsic, near zero threshold devices. A novel improved cross-coupled bridge topology is used to minimize the leakage incurred through the use of intrinsic devices while maintaining their low power turn on characteristics. The fabricated rectifier demonstrates a peak power conversion efficiency (PCE) of 71.5% at 915MHz with a RF input of −4 dBm and a 30 kΩ load. More importantly, a PCE ≫ 30% was measured for all RF input powers between −28 and −4 dBm demonstrating state-of-the-art efficiency across a wide range of input powers.