Digital Calibration Algorithm of Conversion Error Influenced by Parasitic Capacitance in C-C SAR-ADC Based on γ-Estimation

Satoshi SEKINE  Tatsuji MATSUURA  Ryo KISHIDA  Akira HYOGO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E104-A   No.2   pp.516-524
Publication Date: 2021/02/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.2020GCP0008
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
analog-to-digital converter (ADC),  digital-to-analog converter (DAC),  successive approximation register ADC (SAR-ADC),  C-C SAR-ADC,  digital correction,  γ-estimation,  

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C-C successive approximation register analog-to-digital converter (C-C SAR-ADC) is space-saving architecture compared to SAR-ADC with binary weighted capacitive digital-to-analog converter (CDAC). However, the accuracy of C-C SAR-ADC is degraded due to parasitic capacitance of floating nodes. This paper proposes an algorithm calibrating the non-linearity by γ-estimation to accurately estimate radix greater than 2 required to realize C-C SAR-ADC. Behavioral analyses show that the radix γ-estimation error become within 1.5, 0.4 and 0.1% in case of 8-, 10- and 12-bit resolution ADC, respectively. SPICE simulations show that the γ-estimation satisfies the requirement of 10-bit resolution C-C SAR-ADC. The C-C SAR-ADC using γ-estimation achieves 9.72bit of ENOB, 0.8/-0.5LSB and 0.5/-0.4LSB of DNL/INL.