Research And Design Of A Multi-source Energy Harvesting Chip In 0.18μm CMOS Process

With the continuous development and wide application of the Internet of Things(IOT),people’s quality of life and social production levels have been improved.At the same time,the requirements for the power supply and power management of the equipment are constantly increasing.As a technique that can supply power to Io T devices,energy harvesting has become a research hotspot because of its long life and the ability to provide nearly unlimited power.The traditional single-source energy harvesting systems have the defects of low power and limited application,while the multi-source energy harvesting systems can overcome these defects by collecting multiple environmental micro-energy sources.A fully integrated self-powered multi-source energy harvesting system is designed in standard 0.18 μm CMOS process,which can realize the parallel and efficient collection and management of vibration,light,heat and RF energy soures.The multi-source energy harvesting system mainly includes various micro-energy interface circuits,a reconfigurable charge pump and an adaptive control circuit.Among them,the piezoelectric interface adopts synchronous switch collection on capacitors technique with high collection efficiency and full integration capability;Both photoelectric and thermoelectric interface adopt the maximum power point tracking technique based on the fractional open-circuit voltage method,which has the advantages of simple structure,low power consumption,and high reliability;The rectifier in radio frequency interface adopts the threshold voltage self-compensation technique to achieve higher sensitivity and conversion efficiency.The simulation results show that the designed interface circuits can efficiently collect the energy of the transducer.According to the output characteristics of the four interface circuits,and considering the full integration,a high-efficiency reconfigurable charge pump is designed.The charge pump adopts a nested structure,so that it has a higher voltage conversion rate while using as few switches and capacitors as possible;In addition,the charge pump reduces the charge redistribution loss,improves the power conversion efficiency,and expands the input voltage and input power range by adjusting the voltage conversion rate and the switching operating frequency.The simulation results show that the power conversion efficiency of the charge pump is up to 96%.An adaptive control circuit is designed to control the operating state of the interface circuits and the reconfigurable charge pump to ensure the correct operation of the entire system.The circuit use a round-robin priority algorithm to arrange the collection order of each micro-energy;at the same time,the circuit adopts the constant on-time method to regulate the output voltage of the system,thereby the complexity and the power consumption of the circuit is reduced by multiplexing the peak voltage generated by constant on-time to control the operating mode of the charge pump.Finally,on the basis of the above design work,the layout of each module and the overall layout of the system were drawn,and system simulation verification was carried out.The area occupied by the chip is 1872μm×2190μm.The post-simulation results show that the system can self-start in the presence of vibration energy;the overall power consumption of the system is 33μW,and when the four micro-energy sources are collected in parallel,the energy collection efficiency is up to 60.3%.