Title：Capacitance mismatch calibration method and system for successive approximation type analog-to-digital converter
Country：China
Patent No.：202110782723.1
Legal Status：Under review
Inventor：Xinpeng Xing, Zhanpeng Yang, Jingfu Chen
Assignee：International Graduate School at Shenzhen, Tsinghua University
Address：Tsinghua Campus, Xili University Town, Nanshan District, Shenzhen City 518058, Guangdong Province
Filing Date：2021-07-12
Issue Date：
Abstract：
The invention provides a capacitance mismatch calibration method and system for a successive approximation type analog-to-digital converter. The capacitance mismatch calibration method specifically comprises the following steps: S1, inputting a digital random jitter signal and an analog input signal into a capacitance type digital-to-analog converter together; S2, comparing the output of the capacitive digital-to-analog converter with a reference point through a comparator, and storing the obtained output digital code; S3, calculating an evaluation value of the corresponding output digital code; S4, obtaining a correlation coefficient according to the evaluation value and the digital random jitter signal, if the absolute value of the correlation coefficient is close to 0 in an error allowable range, obtaining a correct capacitance weight, otherwise, carrying out feedback adjustment on the capacitance weight, and returning to the step S3; and S5, obtaining an ideal code by compensating the digital code, and updating the digital code. Through injection and digital calibration of the pseudo-random signal in the analog signal domain, a value closer to the actual weight of the capacitor array is obtained, so that dynamic parameters such as the signal-to-noise distortion ratio of the circuit are improved.
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