A Cold Start Circuit with Dynamic Body Biasing for Boost Converter in RF Energy Harvesting System

In this paper, a dynamic body biasing (DBB) technique is proposed and applied to a unit stage of the five-stage Dickson charge pump, which is crucial to the cold start circuit of RF energy harvesting system. Dynamic body-biasing is a wellstudied approach for MOS transistors to tune their threshold voltages, resulting in utilizing the body effect positively to improve the performance of low voltage integrated circuits. This circuit is implemented by using 65nm CMOS process. The simulated results demonstrate that this technique can provide higher current transfer via NMOS switches and improve the load capacity of the charge pump without significant power consumption. The integrated cold start circuit can operate normally with minimum input voltage of 100mV and nanowatt scale available power, and show a maximum efficiency of 60.4% at input voltage of 300mV.