Micro-scale RF Energy Harvesting and Power Management for Passive IoT Devices

A micro-scale radio frequency (RF) energy harvesting and power management solution is proposed in this work to reduce the startup power of energy collection. Analysis of existing energy harvesting solutions determines that controllable connection between the energy storage and boosting modules can maximize energy harvesting. On this basis, a low-power voltage monitoring circuit with a latch function and a feedback control loop circuit with a startup maintenance function are designed. Taking RF energy harvesting as an example, a prototype is designed and fabricated in combination with low-power Wi-Fi scattering communication technology. Measured results show that the system startup voltage is less than 0.7 V, the startup current is less than 200 nA, and the startup power is less than 140 nW, which is more than 20 times lower than the existing energy harvesting solutions. Therefore, the solution can effectively improve energy collection sensitivity, significantly expand the scope of energy collection, and provide an improved and low-cost environmental energy collection solution for hundreds of millions of passive Internet of things devices.