High-precision Bandgap Reference Source Design Based On 55nm Process

Bandgap reference is one of the indispensable modules in integrated circuits.However,as the process size continues to shrink,the requirements for the performance of bandgap reference sources are gradually increasing.Its performance such as high precision,low power consumption and high power rejection ratio directly affects the accuracy and performance of the whole system.Therefore,the study of low-power,high-precision bandgap reference sources is of vital importance to improve system performance.This design is a high precision band gap reference based on 55nm process for use in temperature sensor projects.The thesis firstly introduces the development status of nanoscale process,analyzes the background and significance of the research of high precision bandgap reference source in nanoscale process,the research direction in recent years and draws up the design scheme with the requirements of the temperature sensor project.Next,the thesis gives an overview of voltage reference sources.The bandgap reference,hybrid reference and CMOS reference are analyzed and compared,then the main performance indexes and operating principles of the bandgap reference are described,and finally several mainstream high-order compensations are introduced and analyzed with specific typical circuits.Then,to meet the concept of low supply voltage and the need of second-order compensation circuit,a current-mode structured bandgap circuit is chosen;to reduce power consumption,a subthreshold op-amp is selected;the nonlinearity of V_BEand the selection of resistor are analyzed and a second-order compensation circuit is used to achieve high accuracy.Meanwhile,in order to achieve lower power consumption and maintain higher accuracy,a novel current trim circuit is designed in this thesis using the cutoff leakage current of MOS tube.And the two modes of the circuit are combined,which can be selected according to the actual situation.Finally,Cadence ADE was used to simulate and design the layout of the two high-precision reference circuits based on the SMIC 55 nm process library,and the temperature coefficient of the bandgap reference circuit with second-order compensation was only 1.185 ppm/℃in the operating temperature range of-40℃to 125℃,with a deviation of only 0.5 m V at different process angles.The average temperature coefficient of the Monte Carlo simulation is 2.82 ppm/℃,the average output reference voltage is 1.235 V,1sigma is 2.29 m V,and the temperature coefficient of the post-imitation is 1.73 ppm/℃.The bandgap reference circuit with current trim can output a stable1.2 V The temperature coefficient is only 5.7 ppm/℃.Its power supply rejection ratio can be as high as-51 d B@1 KHz at tt process angle,and the average temperature coefficient of Monte Carlo simulation is 6.23 ppm/℃.The average output reference voltage is 1.2 V,1sigma is 2.1 m V,the current RMS value is about 50μA,and the temperature coefficient of post-imitation is 6.4 ppm/℃.This high-precision bandgap reference source meets the requirements of the design specifications.