| With the development of the Internet of Things and wireless sensor networks,the use of energy harvesting technology instead of batteries to provide continuous and stable power for devices in the Internet of Things has attracted widespread attention.Energy harvesting is powered in a green and nearly permanent way,which can extend the life of devices and Io T systems.Among them,the solar energy harvesting is widely used due to their high energy density,but the traditional energy harvesting system area is large,the cost is high,some studies by the photovoltaic battery and power supply module integrated on the same silicon substrate to save area,to reduce the cost.However,problems such as small input power range,unstable output voltage and low energy harvesting efficiency are still involved in this technology.Aiming at the above shortcomings of on-chip solar cell energy harvesting system,a new high-efficiency on-chip solar cell energy harvesting system is proposed in this thesis.Firstly,based on the basic joint model of on-chip solar cell and charge pump,a new joint model of solar cell and charge pump using charge reusing technology is designed,and the expression of the new model is derived.Secondly,the threshold pressure drop effect of the traditional charge pump and its improvement measures are studied.Aiming at the deficiency of its high reverse leakage current,two kinds of low leakage charge pumps are designed for low voltage conditions.The reverse leakage current in the charge conduction phase is significantly reduced and the conversion efficiency is effectively improved.Finally,a micro-energy harvesting system based on on-chip solar cell is proposed based on the framework of the new joint model designed.A self-adjusting bias voltage generation unit is added to the low-power relaxation oscillator to achieve controllable frequency modulation by changing the output clock signal frequency of the oscillator,and the oscillator is turned off at idle to reduce the power consumption.At the same time,the active diode is added in the high voltage level detector to reduce its area effectively,and the low power consumption voltage is used to regulate the circuit to make the system output stable voltage.In this thesis,the SMIC 40 nm CMOS process is adopted by the system,and the circuit is constructed,the layout is drawn and the simulation is performed on the Cadence Spectre simulation platform.The simulation results show that the maximum load current of the system can reach 6.23 μA under the output voltage of 1.1 V,which is about 41.27% higher than the original system under the same input.In addition,the energy harvesting efficiency of the system is significantly improved,and its peak value reaches 74.16%,which is about 14.76% higher than that of the original system,and the output power is about 3.9 μW.Meanwhile,the input power range of the system is about120 n W to 23,000 n W,and the output power range is about 38 n W to 14,000 n W,are significantly increased. |
