RF Energy Harvesting Circuit with On-chip Antenna for Biomedical Applications

A novel CMOS RF energy harvesting circuit with on-chip antenna is reported. The rectenna system consists of (a) a high efficiency differential full-wave rectifier circuit that converts RF energy to DC power source, and (b) a loop antenna to improve efficiency. To improve area efficiency, the antenna is placed at the perimeter of the chip, occupying only 10-um of each chip edge. Meanwhile, the area enclosed by the loop antenna is fully populated with other circuitries. The system is implemented in a 0.13-um digital CMOS technology, and it is able to harvest 0.5-uW from a 4-GHz + 20-dBm RF source 7-cm away. Measured result also shows that the antenna improves RF receive gain by 30-dB compared with the same system without the antenna. The harvested energy is sufficient to power up simple digital circuits such as implantable RFID, and the total area is only 0.16-mm(2).