| With the rapid development of the Internet of Everything,people,data,and various things will be connected to be interacted and shared,leading to the development of smart nodes.Each smart node includes a system-on-chip,and the design of the chip in this article provides energy for those smart nodes.They collect micro energy in the environment and reused it.It is not only more environmentally friendly,but also plays a very important role in scenarios where it is inconvenient to replace the battery,greatly improving the quality of people’s lives.First of all,this thesis conducts detailed investigation and study on the design of power management chips based on energy harvesting at home and abroad,proposes corresponding solutions to unsolved problems of the current research,and conducts a detailed analysis on the design principles.By comparing the design of power management solutions in recent years,starting from the two aspects of the adjustable ratio of the switched capacitor voltage converter and the maximum power point tracking,a power management chip which is suitable for solar energy harvesting system is designed.Then it introduces the main components of the system in detail,mainly including switched capacitor voltage converter,feedforward control voltage regulator,finite state machine and digital controlled oscillator.The overall structure of each module and their connections are introduced.On this basis,the system’s self-starting function and self-sustaining function are clarified,and at the same time,a switch is added between the system and the load to reduce the impact of load changes on the power management chip.Next,the different modules are introduced in detail,and the design method and performance indicators of the switched capacitor voltage converter are theoretically deduced,so as to design a switched capacitor voltage converter with an adjustable ratio.For different input voltages,the voltage conversion efficiency of the voltage converter can always be maintained in a higher range;for the voltage regulator,this article compares the feedback control and the feedforward control,and introduces the specific feedforward voltage regulation control used in this article,including the working process,advantages and disadvantages of the scheme;for the control of the entire system,a finite state machine for the mutual conversion of the control system between different working states is designed;finally,for the clock module,this paper introduces three different types of the working principle of the oscillator in detail,and summarizes three different frequency modulation methods.Finally,the power management chip is implemented in 0.18μm CMOS technology.Verification and analysis of the post-simulation is proposed after extracting the parasitic parameter in the layout.It can be seen from the simulation results that this design can achieve 1.8V boost results with different boost ratios for different input voltages from 0.3V to0.7V.The voltage regulator module works normally.Self-starting and self-maintaining functions are also realized,and its energy conversion efficiency can also be maintained above60%.The chip area is 0.355mm~2,fitting the design requirements. |
