一种用于生物医学信号的自适应SAR ADC  

A Self-Adaption SAR ADC for Biomedical Signals

作　　者：刘凯 张瑛[1,2] 马乾 黄常华[1,2] LIU Kai;ZHANG Ying;MA Qian;HUANG Changhua(College of Elec.and Optical Engineer.&College of Microelec.,Nanjing Univ.of Posts and Telecomm.,Nanjing210046,P.R.China;National and Local Joint Engineer.Lab.of RF Integr.and Micro-Assembly Technol.,Nanjing Univ.of Posts and Telecomm.,Nanjing210046,P.R.China)

机构地区：[1]南京邮电大学电子与光学工程学院、微电子学院,南京210046 [2]南京邮电大学射频集成与微组装技术国家地方联合工程实验室,南京210046

出　　处：《微电子学》2021年第5期613-619,共7页Microelectronics

基　　金：国家自然科学基金资助项目(61106021);中国博士后科学基金资助项目(2015M582541)。

摘　　要：基于0.18μm CMOS工艺,设计了一种用于生物医学信号的12位逐次逼近型模数转换器(SAR ADC)。数模转换器采用分段结构电容阵列,并加入1位冗余位。比较器采用互补输入对管构成的动态比较器,以减小噪声和功耗。栅压自举开关被用于采样保持电路,并增加了堆叠管和虚拟管。针对生物医学信号具有稀疏性的特点,通过延时上极板复位时间的方法检测两次采样电压差值,实现采样率自适应切换。仿真结果表明,在120kS/s采样率、1V电源电压的条件下,该SAR ADC的功耗仅为4.65μW,无杂散动态范围为76.29dB,优值为16.9fJ/(conv·step),有效位数达11.16bit。A 12bit successive approximation register(SAR)analog to digital converter(ADC)for biomedical signals was designed in a 0.18μm CMOS process.A segmented capacitor array with one redundant bit was adopted in the digital to analog converter(DAC).The comparator used a dynamic comparator composed of complementary input pairs to reduce its noise and power consumption.The gate voltage bootstrap switch with stack transistors and virtual transistors was used in the sample-and-hold circuit.Besides,aiming at the sparsity of biomedical signals,the difference between the two sampling voltages was detected by delaying the reset time of the upper plate.Then the sampling rate could be switched adaptively.Under the condition of 120kS/s sampling rate and 1Vsupply voltage,the simulation results showed that the SAR ADC consumed only 4.65μW,the spurious-free dynamic range(SFDR)was 76.29dB,the figure of merit(FOM)was 16.9fJ/(conv·step),and the effective number of bit(ENOB)reached 11.16bit.

关 键 词：生物医学信号 逐次逼近型ADC 自适应采样率 冗余 低噪声比较器 

分 类 号：TN792[电子电信—电路与系统]