Research And Design Of CMOS RF Energy Harvesting Chips For Self-powered Systems

With the development of semiconductor technology and the advancement of design technology,the power consumption of wireless sensors,wearable devices and implantable chips has become lower and lower,and it is possible to directly collect the weak energy in the environment to power itself.In this thesis,the radio frequency energy harvesting technology for self-powered systems is studied in depth,and the standard 0.18 ?m CMOS process is used to design and implement it.The RF energy harvesting circuit mainly includes a matching network,a RF-DC rectifier and voltage multiplier,an ultra-low power reference voltage circuit and a LDO circuit.Among them,the matching network increases the amplitude of the input signal and reduces the transmission loss of energy.The RF-DC rectifier and voltage multiplier adopts a new self-compensation technology to improve the output voltage of the circuit,thus improving the rectification efficiency.The ultra-low power reference voltage circuit provides high precision reference voltage for LDO circuit.The LDO circuit provides a stable voltage with low ripple for the load.The simulation results show that the chip can collect RF energy with a frequency of 900 MHz and sensitivity of-20 dBm,the power conversion efficiency of the circuit reaches 40%,and the output DC voltage reaches 1.8V.In order to further improve the function of the RF energy harvesting circuit,an improved RF energy harvesting circuit is proposed,which mainly adds an ultra-low power reference current source circuit,a self-starting circuit,an energy management circuit and an auxiliary circuit.The current reference circuit provides high precision bias current for the system.The self-starting circuit makes the system perform start-up process without RF energy in the environment or energy storage in the system.The energy management circuit enables the system to store energy and supply power to the system under specific conditions,thus increasing the energy utilization of the system.The auxiliary circuit enable the system to work stably and normally.The chip has an area of 390?m×320?m,and the quiescent current does not exceed 260 nA.Without reducing the performance of the circuit,the pre-storage of energy is realized,and the circuit can be started automatically according to the strength of the environmental energy.