| Paper Abstract and Keywords |
| Presentation |
2026-03-27 09:25
A Single-Slope ADC CMOS Image Sensor Based on a Distributed Architecture of Stepless-Acceleration Ramp Generators
Hayato Sakoda, Toshinori Otaka, Shunichi Sato, Takayuki Hamamoto (TUS) |
| Abstract |
(in Japanese) |
(See Japanese page) |
| (in English) |
Achieving both high resolution and high-speed operation is a critical challenge for single-slope analog-to-digital converters (SS-ADCs) widely used in CMOS image sensors (CIS) with increasing pixel counts and shrinking pixel sizes. To address this, we have focused on a "ramp waveform modulation approach" that requires no major design modifications to the column circuitry. We previously proposed a stepless acceleration ramp method using distributed multiple-integration circuits to resolve the image quality degradation inherent in conventional piecewise-linear ramp schemes. This paper reports the evaluation results of a prototype chip implementing this method. Along with demonstrating theoretically smooth ramp waveform generation on silicon, we address the noise amplification issue specific to on-chip correlated double sampling (CDS) architectures that mix nonlinear signal conversion with linear reset conversion. To solve this, we introduced a linearization process combining inverse mapping to a linear space via a pixel-level look-up table (LUT) optimized for each pixel's operating point, followed by external offset correction via subtraction using dark data under the same ramp gain setting. Consequently, we eliminated the spatial and temporal noise modulation problems in high-illuminance regions caused by the acceleration ramp, demonstrating high-speed ADC operation maintaining an image quality comparable to that of a linear ramp even at high-illuminance levels. |
| Keyword |
(in Japanese) |
(See Japanese page) |
| (in English) |
CMOS Image Sensor / Single-Slope ADC / Stepless Accelerated Ramp / Distributed Ramp Architecture / / / / |
| Reference Info. |
ITE Tech. Rep., vol. 50, no. 14, IST2026-12, pp. 7-12, March 2026. |
| Paper # |
IST2026-12 |
| Date of Issue |
2026-03-20 (IST) |
| ISSN |
Online edition: ISSN 2424-1970 |
| Download PDF |
|
| Conference Information |
| Committee |
IST |
| Conference Date |
2026-03-27 - 2026-03-27 |
| Place (in Japanese) |
(See Japanese page) |
| Place (in English) |
Kikai-Shinko-Kaikan Bldg. |
| Topics (in Japanese) |
(See Japanese page) |
| Topics (in English) |
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| Paper Information |
| Registration To |
IST |
| Conference Code |
2026-03-IST |
| Language |
Japanese |
| Title (in Japanese) |
(See Japanese page) |
| Sub Title (in Japanese) |
(See Japanese page) |
| Title (in English) |
A Single-Slope ADC CMOS Image Sensor Based on a Distributed Architecture of Stepless-Acceleration Ramp Generators |
| Sub Title (in English) |
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| Keyword(1) |
CMOS Image Sensor |
| Keyword(2) |
Single-Slope ADC |
| Keyword(3) |
Stepless Accelerated Ramp |
| Keyword(4) |
Distributed Ramp Architecture |
| Keyword(5) |
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| Keyword(6) |
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| 1st Author's Name |
Hayato Sakoda |
| 1st Author's Affiliation |
Tokyo University of Science (TUS) |
| 2nd Author's Name |
Toshinori Otaka |
| 2nd Author's Affiliation |
Tokyo University of Science (TUS) |
| 3rd Author's Name |
Shunichi Sato |
| 3rd Author's Affiliation |
Tokyo University of Science (TUS) |
| 4th Author's Name |
Takayuki Hamamoto |
| 4th Author's Affiliation |
Tokyo University of Science (TUS) |
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| Speaker |
Author-1 |
| Date Time |
2026-03-27 09:25:00 |
| Presentation Time |
15 minutes |
| Registration for |
IST |
| Paper # |
IST2026-12 |
| Volume (vol) |
vol.50 |
| Number (no) |
no.14 |
| Page |
pp.7-12 |
| #Pages |
6 |
| Date of Issue |
2026-03-20 (IST) |