Design And Implementation Of High Temperature Bandgap Reference Source On CEPC Vertex Detector Chip

The power consumption and heat dissipation of the vertex detector in modern high energy physics experiments have gradually become the main factors to be considered in the design of the vertex detector chip.Increasing the working temperature of the vertex detector chip can alleviate its power consumption and heat dissipation requirements.The increase of working temperature will lead to the drift of working point and bias voltage of vertex detector chip module.A reference voltage source that can be stable at high temperature can provide a stable reference for each module on the vertex detector chip,and is an important prerequisite for the design of the vertex detector chip working at high temperature.MIC4 chip is a pixel detector chip designed for the pre-research project of CEPC(Circular Electron Positron Collider)vertex detector.Considering the power consumption and heat dissipation requirements of CEPC vertex detectors in the future,a bandgap reference source which can work at high temperature is designed as a reference voltage source for the internal module of the chip.It lays a foundation for the design of the chip at high temperature.This paper present the working principle and performance index of the reference voltage source are analyzed theoretically in the first place,and the design of bandgap reference used in MIC4 chip of vertex detector is introduced emphatically.Based on towerjazz 0.18um technology,the designed bandgap reference circuit can work normally at high temperature.By testing the bandgap reference at high temperature,the maximum temperature that MIC4 chip can withstand under towerjazz 0.18um technology can be obtained.Although the bandgap reference source of multi-order curvature compensation circuit has some advantages in power supply rejection ratio,temperature coefficient and other parameters,the structure of the bandgap reference source is more complex.Under the influence of high temperature environment,too complex structure will lead to the reference source can not achieve the desired property.So in this paper,the traditional transistors are replaced by diodes,which have better temperature coefficient than the transistors,and the circuit structure is modified to make the bandgap reference source in this paper more compact than the traditional bandgap reference source with multi-order curvature compensation circuit structure,at the same time,it can also have a higher power rejection ratio.In the temperature range o f-45?-85?,The temperature coefficient of the reference source is 3.16 ppm/C,the output voltage is 1.205V,and the power supply rejection ratio is 73.28dB.Finally,the test results of the bandgap reference source are introduced.The bandgap reference source has been integrated into the MIC4 chip of the CEPC vertex detector with a test interface.The test results show that the output voltage amplitude of the reference source is 1.199V at room temperature,which basically meets the requirements of the MIC4 chip of the CEPC vertex detector.The more exciting thing is that the bandgap reference can work normally under the temperature of 150?.This design can provide some reference for the design of the bandgap reference source of the next generation chip at high temperature.