Energy scavenging for mobile and wireless devices using high-efficiency rectifier circuit

This project is to develop a high-efficiency RF to DC rectifier using CMOS technology for an energy harvesting system. Energy harvesting or energy scavenging is the process to harvest ambient energy from the atmosphere such as solar energy, RF energy, vibration energy or thermal energy to a usable electrical signal. RF energy harvesting is getting more demand because the density of the wireless communications devices rapidly increases in metropolis area. This power extraction method able to solve the growing demand for power supply to the low-power electronics. Therefore, high efficiency of RF to DC rectifier is crucial. A high-efficiency CMOS based rectifier has been developed enabling the integration of rectifier into any wireless devices and mobile phone. Parametric simulations to the rectifier were done to investigate factors that affect the power conversion efficiency of the rectifier. Circuit parameters that been analysed including the sizing of the transistor, the threshold voltage of the devices, load impedance, inter-stage capacitor and number of stages of the rectifier. By using the optimized parameter set, we successfully achieve 13.3% of conversion efficiency in a single stage rectifier. The conversion efficiency decreases to 8.5% by increasing the number of rectifier’s stages to three.