Power-loss reduction of a MOSFET cross-coupled rectifier by employing zero-voltage switching

Ubiquitous monitoring of sensor data and long term reliable operation of sensor units have been studied extensively either for environmental monitoring or for biomedical applications. Long term operation of sensor units requires continuous wireless signal at the output. The proposed rectifier unit is designed and simulated using 0.5-μm standard CMOS process. Simulation results show that power supply from an external source to avoid unwieldy wires or periodic battery replacements. Inductive-power transfer, as a suitable way of driving the sensor electronics, needs a high efficiency rectifier unit to convert the harvested wireless energy into a usable DC level. However, conventional full-wave bridge rectifier with a lower output voltage and a significant power loss lowers the overall efficiency of the inductive-link system. In this paper, a class-E type zero-voltage-switching structure is presented to achieve a high efficiency rectifier circuit. The symmetrical differential class-E switching structures are driven by differential AC signals that result in a low-loss full-wave rectified the proposed rectifier circuit can achieve more than 76% power conversion efficiency for an input AC signal of 7 MHz frequency with signal amplitude of 2 V (peak).