On the RF energy harvesting based on CMOS technology

RF energy harvesting has been recognized as one of the possible options for powering embedded and remote electronic devices. There are technologies and products, such as wireless charging, RFID systems, remote charging, available which have demonstrated the technical feasibilities provides that the power level of the RF sources are sufficient. However for ambient low-power RF energy harvesting, it is still a quite challenging technical issue. Due to the regulation on RF power level emission in the available systems and the use the mainstream digital CMOS technology for implementation, the achievable power level and power efficiency are still far below the requirements of most applications. To maximize the conversion efficiency and to acquire sufficient energy, optimal designs for every building blocks of the harvesting system are required. This review highlights some methods to enhance the RF/DC conversion such as using low-threshold PMOS devices, body biasing, gate compensation, for full-wave rectifying, low-loss CMOS switches for charge pump design, and adaptive voltage regulation using pulse-skipping modulation technique.