The Design Of A High Conversion Efficiency Charge Pump For Energy Harvesting

The energy harvesting circuit supplies power to low-power applications such as Internet of Things(Io T)nodes by harvesting the energy in the environment.Due to the limited energy in the environment,the energy harvesting circuit is required to have high conversion efficiency.The efficiency of the energy harvesting circuit is mainly determined by the boost circuit in the circuit,existing mainstream boost circuits include inductance-based boost circuits and charge pump-based boost circuits.A high-efficiency charge pump circuit has been designed for energy harvesting.The design of the main charge pump circuit and auxiliary modules have been completed.The auxiliary modules include clock generators,reference circuits and comparators circuit.The core circuit is the design of the main charge pump circuit,which is mainly realized from three aspects: reducing leakage loss,reducing conduction loss and the number of charge pump stages can be adjusted.Analyzing the loss factors in the main charge pump circuit that affect the conversion efficiency,and then generate a specific clock signal to avoid the generation of reverse leakage current in the main charge pump circuit,and add a dynamic inverter to reduce the conduction resistance of the switch transistors,so as to realize the optimization of the leakage loss and conduction loss in the main charge pump circuit,and realize the main charge pump circuit with high conversion efficiency.The way that the number of charge pump stages can be adjusted allows the circuit to have high conversion efficiency within the input voltage of 300 m V?500m V,avoiding the introduction of additional charge pump stages and unnecessary losses when the input voltage is high.The pulse skipping modulation method is adopted to keep the output voltage of the circuit basically stable,that is,the output voltage is stabilized at about 800 m V by sampling the output voltage and comparing it with the reference voltage and then controlling the enabling of the clock.Based on the SMIC 180 nm process,a high-efficiency charge pump circuit for energy harvesting is designed and its layout area is 0.12 mm~2.The post-simulation results show that the output voltage of the charge pump circuit is stable at about 800 m V in the temperature range of-20??85? under the full corner.When the input voltage is 300 m V?500m V;the maximum output power can reach 15.3?W;when the input voltage is 300 m V and 500 m V,its peak efficiency can reach 73.81% and 77.1%,respectively.