The Design Of Low Offset Bandgap Based On 40nm Process

Bandgap Reference source is an important module in the analog circuit,which is widely used in many circuits,such as ADC,DAC,LDO and other analog or mixed circuits;its performance directly affects the accuracy of the system.In recent years,the power voltage has been reduced with the decreasing of the characteristic size in IC,and the demand to the reference is more and more high.As a result,it is very important to research the CMOS bandgap reference.The thesis presents a design of a bandgap reference source with low offset multi-output based on the TSMC40 G CMOS process.The non ideal factors(mismatch)very serious influence on the performance of the circuit due to the adoption of 40 nm technology.This paper firstly analyses the non ideal factors of CMOS technology and specific expression of bandgap reference based on DC offset.The chopper technology was adopted to reduce DC offset influence on the bandgap reference voltage accuracy.The simulation result show that the output voltage accuracy of the bandgap reference without chopper technology and with chopper technology are respectively 4.73% and 2.36%.Obviously,the bandgap reference output voltage accuracy with chopper technology is improved by 50%.Based on this high accuracy bandgap,a DAC circuit scaling by voltage was design.This circuit realized one choose from 32.The simulation results show that,the output voltage is incremented by 0.0375 V,when the select signal is 00000,corresponding to the minimum voltage of 0.375V;when the select signal is 11111,corresponding to a maximum voltage of 1.2V.After the circuit design,Complete the layout design and simulation.The simulation parameters include voltage accuracy,temperature coefficient,linear adjustment rate.The results show that the layout parameters to achieve the desired objectives.