title: Two-step single slope/SAR ADC with error correction for CMOS image sensor.
abstract: Conventional two-step ADC for CMOS image sensor requires full resolution noise performance in the first stage single slope ADC, leading to high power consumption and large chip area. This paper presents an 11-bit two-step single slope/successive approximation register (SAR) ADC scheme for CMOS image sensor applications. The first stage single slope ADC generates a 3-bit data and 1 redundant bit. The redundant bit is combined with the following 8-bit SAR ADC output code using a proposed error correction algorithm. Instead of requiring full resolution noise performance, the first stage single slope circuit of the proposed ADC can tolerate up to 3.125% quantization noise. With the proposed error correction mechanism, the power consumption and chip area of the single slope ADC are significantly reduced. The prototype ADC is fabricated using 0.18 μ m CMOS technology. The chip area of the proposed ADC is 7 μ m × 500 μ m. The measurement results show that the energy efficiency figure-of-merit (FOM) of the proposed ADC core is only 125 pJ/sample under 1.4 V power supply and the chip area efficiency is 84 k  μ m(2) · cycles/sample.
authors.affiliation: College of Communication Engineering, Chongqing University (CQU), China.
authors.forename: Fang
authors.identifier: 0000-0003-2453-4878
authors.initials: F
authors.lastname: Tang
authors.affiliation: Hong Kong University of Science and Technology (HKUST), ECE Department, Clear Water Bay, Kowloon, Hong Kong.
authors.forename: Amine
authors.initials: A
authors.lastname: Bermak
authors.affiliation: School of Computing, University of the West of Scotland, UK.
authors.forename: Abbes
authors.initials: A
authors.lastname: Amira
authors.affiliation: Qatar University, Qatar.
authors.forename: Mohieddine
authors.initials: M
authors.lastname: Amor Benammar
authors.affiliation: School of Mathematics and Statistics, Wuhan University, Wuhan, China.
authors.forename: Debiao
authors.identifier: 0000-0002-2446-7436
authors.initials: D
authors.lastname: He
authors.affiliation: College of Electronic Science and Technology, Shenzhen University, Shenzhen, China.
authors.forename: Xiaojin
authors.initials: X
authors.lastname: Zhao
mesh_terms: D000465:Algorithms; D002138:Calibration; D012666:Semiconductors / Q000592:standards*