Design Of Low-power DC-DC Circuit For Low-voltage Energy Harvesting

With limited battery capacity of Io T,smart wearable products and other small electronic devices,even though they have low standby power consumption,it is still difficult to maintain long operating time without continuous power supply.However,there is much green energy available in the natural environment,such as solar energy and thermal energy,if the energy harvesting technology is used for self-powered or battery storage of various low-power small electronic devices,it can extend their operating time.In this thesis,a low-power DC-DC circuit for low-voltage energy harvesting is designed with low-voltage(0.8V-2.5V)input source,which mainly consists of a lowpower Boost Converter and a low-power LDO circuit.Firstly,this thesis introduces the common architecture and basic working principle of Boost Converter and LDO circuit,and proposes a DC-DC circuit system scheme with low-power Boost Converter at the front stage and low-power LDO circuit at the back stage cascaded according to the demand of low-voltage energy harvesting.Secondly,based on the characteristics that the input source energy of low-voltage energy harvesting system is normally weak and the load current is normally intermittent,the system architecture of Boost Converter with voltage and current hysteresis loop control mode based on Burst mode is determined,and the Boost Converter is adaptively switched between SLEEP mode and ACTIVE mode in accordance with the load current,and thanks to the extremely low quiescent current in SLEEP mode,the Boost Converter still has excellent conversion efficiency under light load.Finally,the thesis further designs a low-power LDO circuit with adaptive biased current buffer and "Ahuja" frequency compensation scheme to meet the needs of low ripple application conditions,which ensures that the LDO circuit can maintain loop stability at very low quiescent current.The design and layout design of the low-power DC-DC circuit for low-voltage energy harvesting is based on the 0.25μm BCD process,and the simulation results show that the DC-DC circuit can operate normally at low-voltage input from 0.8V to 2.5V,where the output voltage of the Boost Converter is 3.6V and the output voltage of the LDO circuit is 3.3V.The Boost Converter has a maximum load capability of 100 m A at low boost ratio(3.6V/2.5V),a conversion efficiency of 91.781% at a light load of 100μA and a peak conversion efficiency of more than 93.758%.The overall quiescent current consumption of the DC-DC circuit is about 2.3μA at no load.The final test results show that the basic functions of the DC-DC circuit are complete and the chip can work properly.