Radio-Frequency Energy Harvesting Chip for ISM 915 MHz Antenna

This study presents a radio-frequency (RF) energy harvesting chip, which is fed with the ISM (industrial, scientific and medical) 915 MHz antenna. The proposed chip includes the RF-DC rectifier, over-voltage protection circuit, low dropout regulator (LDO) and charging control circuit, which are all designed and simulated in standard TSMC 0.18 um 1P6M CMOS process. The off-chip matching network is used not only to obtain the maximum power deliver from antenna to rectifier, but also to have the maximum conversion efficiency. A native MOSFET is adopted to design the RF-DC rectifier with low threshold voltage. According to the simulated results, the input return loss and maximum conversion efficiency are -52.546 dB and 43.6 %, respectively, at the input power of -7 dBm and the ISM band of 915 MHz, which varies from 870 MHz to 996 MHz. The output voltage of the RF-DC rectifier is limited from 1.77 to 1.79 volts as the input power varies from -13 dBm to 10 dBm. Passing through the LDO circuit, a stable voltage of 1.5 V is supplied to the charging control circuit.