Design Of Ultra Low Power And High Precision Voltage Reference

With the popularity of the Internet of Things and wearable medical devices,power consumption has increasingly become a major consideration in circuit design.For power consumption,we mainly consider two aspects broaden sources of income and reduce expenditure.From the aspect of broaden sources of income,we can used wind and solar power mechanical power,and wireless radio frequency energy.From the aspect of reduce expenditure,we can improve the working life of the device by reducing the power consumption of the system.For analog circuit design,it can be achieved by reducing the power voltage,designing a new circuit architecture,and so on.For ADC,DAC and other circuits,the reference voltage source is essential in analog circuits.How to design a reference source circuit which can work under low voltage,has low output reference voltage and low power consumption is imminent.The main work of this paper is as follows:(1)A high precision voltage reference circuit is designed using bipolar junction transistor.The output reference voltage is 169 mV.At typical process corner,the temperature coefficient is only 4.35 ppm/?.At different process corner,the output voltage deviation is less than 1 mV.(2)Using the MOSFET working in the sub-threshold region,an ultra-low power voltage reference circuit is designed.The gate grounded native NMOS is used as the bias current source to supply the selfbiased MOSFET to generate the reference voltage.The output voltage of the traditional low-power reference circuit is based on the threshold voltage of NMOS,but because of the poor process stability of the threshold voltage of NMOS,the accuracy of the output voltage is poor.The output reference voltage of the reference voltage source designed in this paper is based on the difference of threshold voltage,improve the absolute accuracy of the reference voltage.(3)In order to further improve the absolute accuracy of the ultra-low power voltage reference,a digital trimming circuit is designed.The self biased structure load in the circuit can be adjusted by eight bit control code.Specifically,the width length ratio of the load MOSFET is adjusted by changing the number of parallel MOSFET.(4)By combining the high precision reference circuit with the ultra-low power reference circuit,the ultra-low power and high precision reference circuit is realized.Taking the output of the high-precision reference as a reference,the ultra-low power consumption reference circuit is automatically adjusted by the control circuit.After the adjustment is completed,the high-precision reference circuit is closed to save power.The designed structure has been verified by TSMC 180 nm process and achieved the design goal.