A 12 Bit 4.7-MS/s 260.5μW Digital Feed-Forward Incremental-ΣΔ-SAR ADC in 0.13μm CMOS for Image Sensors

Fortunato Frazzica, Toshio Yasue, Annachiara Spagnolo, David San Segundo Bello, Maarten De Bock, Jan Craninckx, Piet Wambacq

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


This paper presents a 12 bit, 4.7 MS/s Digital Feed-Forward Incremental ΣΔ - Successive Approximation Register (DFF I- ΣΔ -SAR) Analog-to-Digital Converter (ADC) for column readout of image sensors. An input range detection phase and a new switching scheme for the DAC in the first stage allow reaching the desired 4 bit resolution of the I- ΣΔ stage with an Over Sampling Ratio (OSR) of 8. A second stage SAR converts the I- ΣΔ residue voltage resolving the 8 Least Significant Bits (LSBs). The ADC is integrated in a test chip with a Source Follower (SF) test unit that emulates a pixel array and is fabricated using 2-Poly-4-Metal 130 nm CMOS technology. The ADC operates under 3.3 V/1.2 V supply voltages, achieving a DNL of −0.43/0.62 12 bit LSBs, 356 μV rms noise, equivalent to 9.2 bit ENOB at a sampling frequency of 4.7 MS/s with an OSR of 8. The proposed ADC consumes 260.5 μW of power, yielding a Walden Figure-of-Merit 94 fJ/c.s.. The core area is 18400 μm2 .
Original languageEnglish
Pages (from-to)21653-21666
Number of pages14
JournalIEEE Sensors Journal
Issue number19
Publication statusPublished - 1 Oct 2021

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  • Analog to digital converter (ADC)
  • CMOS image sensor (CIS)
  • CMOS image sensor readout
  • incremental Sigma Delta ADC
  • successive approximation register (SAR) ADC
  • ultra-high-definition-tele-vision (UHTV)
  • virtual-reality (VR)
  • 16k resolution


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