Designand Research Of SAR ADC Chip With High Temperature Resistanceand High Precision

An analog-to-digital Converter(ADC)is a type of interface circuit chip which converts analog signals into digital signals.With the development of integrated circuit technology and electronic information technology,high precision signal acquisition systems require ADCs which are more resistant to high temperatures,meanwhile having higher resolution and less power consumption.In high temperature operating environments such as oil exploration and aerospace,sensor signals acquisition always tend to be more efficient and more accurate,therefore the pursuit of ADC performance is never stopped.Advanced process developments drive higher levels of integration and faster transistors inside chips,which is conducive to design faster ADCs,but also brings new challenges.Compared with the rapid development of semiconductor fabrication technology,the progress of chip cooling technology is relatively slow.With the rapid increase of ADC power consumption and function,the internal temperature of the chip rises up thus the performance deteriorates,which causes reliability issues in ADC performance at high temperature environment.Therefore,to ensure the high-quality performance of ADC in high temperature environment has become an unavoidable research direction.The research results of this paper have important academic and engineering significance for applications in high temperature environments such as oil exploration and aerospace,which can improve the durability and integration of the circuit while ensuring the accuracy of the ADCThe structure of SAR ADC,including digital integration,low power circuit design and noise shaping technology,is described by deep analysis of SAR ADC.In this paper,a high precision thermal noise model of SAR ADC is established,and a digital temperature compensation method of built-in CMOS temperature sensor is proposed.Finally,the solutions of related technical problems are given.The highperformance digital CMOS temperature sensor is used to measure temperature,which overcomes the complexity of traditional analog temperature compensation reference voltage circuit.Therefore,the digital compensation of high precision SAR ADC conversion weight at high temperature is realized.The performance of the designed second-order noise shaping SARADC chip was tested at high temperature.At 175 ℃,before temperature compensation the SNDR performance of the noise shaping SAR ADC was only 74.7 d B,which could not meet the performance requirements of SAR ADC in the high temperature environment.After temperature compensation,the SNDR performance of the noise shaping SAR ADC is improved to 87.3 d B with an effective bit of 14.2 bits,in which the effective bit is improved by 2.1 bits.The noise shaping SAR ADC with temperature compensation meets the performance requirements of the high temperature and high precision ADC.