| With the wide application of wireless sensor in the Internet of things,the disadvantages of using traditional to supply are becoming increasingly serious,there are more and more attention having been paid to the self-power supply of sensors using energy harvesting technology.The DC-DC boost circuit for tiny solar energy harvesting is difficult to self-start when the input voltage is very low,furthermore,the output voltage swing is very large.This paper mainly studies the tiny solar energy collection.Due to the low output voltage of the transducer,the traditional DC-DC boost circuit for tiny solar energy harvesting cannot start up and collect tiny solar energy.In view of the current situation,this paper designs a DC-AC-DC voltage booster converter for tiny solar energy collection.The converter of three modules are mainly designed and emulated: DC-AC inverter module,AC-DC rectifier module,linear voltage regulator with free-capacitor.The finally output voltage of the circuit can directly provide a stable voltage to the load.The mainly work of this paper is as follows:(1)The characteristics of solar cells have been given further study,on which basis the required macro circuit structure has been designed according to the value of output voltage.this paper puts forward a circuit structure which can use the inverter to step up firstly and then use the rectifier get the DC voltage,this circuit realize self-starting in low input voltage,with the minimum of only 48 m V.(2)To solve the problem of self-starting of inverter under low input voltage,the self-starting method of traditional DC-DC boost has been studied.And based on the structure of transformer,this research has designed the inverter circuit utilizing the depletion type MOS transistor as a switch to guarantee a continuous AC output of the secondary coil.(3)How to reduce the voltage drop of the rectifier circuit and improve the efficiency is studied.Although the passive rectifier circuit can further reduce the voltage drop of the circuit,its efficiency is relatively low.In view of that,this paper has designed the full wave active rectifier circuit with a negative voltage conversion circuit and the active diode to change the voltage phase and improve the circuit efficiency.There are only half areas compare with the full wave active rectifier.The voltage conversion efficiency is 98%.In addition,to successfully activate the circuit at any process angle,the study has also designed a substrate adjustment circuit and bypass diode.(4)To achieve a stable output voltage,a linear voltage regulator without external chip capacitors is designed.And to resolve overshoot and subduction of the transient response caused by no external capacitor,the suppression of the overshoot circuit of the overshoot has been designed which will improve the transient response of the circuit.The subduction voltage is 121 m V and the overshoot voltage is 50 m V when the load is changing.The band gap with zero temperature coefficient is designed,the temperature coefficient is 10ppm/°C.The output voltage of the load regulation is 50? V/m A.This paper has designed DC-AC-DC booster converter.The design and simulation are carried out by Spectre simulation tool which is including the Chartered 0.35?m CMOS process library.The simulation results show that the minimum self-starting voltage of the system is 48 m V.The output voltage of the load regulation is 50 u V/m A.When the load is changing,when the output voltage is set to 1.8V,the maximum output is 1.82 V and the minimum output is 1.72 V. |
PDF Full Text Request