Far-Field Radio Frequency Energy Harvesting Chip For Passive Wireless Sensor Network

Far field passive radio frequency energy harvesting chip can convert the RF signal to a stable dc voltage and drive the load. It is mainly used in passive wireless sensor network (WSN) for power supply, and it can also be used in RFID tags as power source of tags. It has many advantages, such as wireless connection, energy receiving at long distance, small size, long life, no maintenance, etc. This energy harvesting circuit consists of CMOS RF-DC voltage multiplier and rectifier, ultra-low power reference voltage generating circuit, energy judging circuit and low drop-out linear regulator. The whole chip is compatible with standard CMOS process, and it is in line with the portability and miniaturization of sensor network nodes.Firstly, this thesis introduces the structure and basic principle of the passive far field radio frequency energy harvesting system, and analyzes the basic principle and circuit structure of each module. Then it elaborates the design of each module of the chip, including the detail circuit implementation, layout design, and pre and post simulation of each module.The energy harvesting chip design is designed in TSMC90nm process. The results of pre and post simulations demonstrate that the performance of the desige meet the requirements. The chip can harvest RF energy and output a stable dc voltage to drive the load. The sensitivity of the whole chip is better than-24dBm(4μW). The output voltage value of the chip can automatically switch to IV or3V according to the value of the input energy. If the input energy is lower than the set threshold the output is IV, otherwise the output is3V. When driving a1MΩ load, the output voltage of the CMOS RF-DC voltage multiplier and rectifier can reach1.4V, meanwhile, energy conversion efficiency can reach49%. When the input energy is4dBm and the load resistance is greater than60kΩ, the output voltage can be more than2.9V. The supply voltage of the ultra-low power reference voltage generating circuit can be less than IV, the temperature coefficient of its output voltage is less than220ppm/℃in the range of-25℃-80℃with the total power consumption less than100nA. Energy judging circuit realize an adaptive output voltage of the chip to the value of input energy, meanwhile, if the input energy is high, it can provide more currents to the LDO. As the output stage, the ultra low power LDO circuit can drive the load.