Compensation for Process and Temperature Dependency in a CMOS Image Sensor

This paper analyzes and compensates for process and temperature dependency among a (Complementary Metal Oxide Semiconductor) CMOS image sensor (CIS) array. Both the analysis and compensation are supported with experimental results on the CIS’s dark current, dark signal non-uniformity (DSNU), and conversion gain (CG). To model and to compensate for process variations, process sensors based on pixel source follower (SF)’s transconductance gm,SF have been proposed to model and to be compared against the measurement results of SF gain ASF. In addition, ASF’s thermal dependency has been analyzed in detail. To provide thermal information required for temperature compensation, six scattered bipolar junction transistor (BJT)-based temperature sensors replace six image pixels inside the array. They are measured to have an untrimmed inaccuracy within ±0.5 ⁰C. Dark signal and CG’s thermal dependencies are compensated using the on-chip temperature sensors by at least 79% and 87%, respectively.

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Low-Cost 2D Index and Straightness Measurement System Based on a CMOS Image Sensor

Sensors ◽

10.3390/s19245461 ◽

2019 ◽

Vol 19 (24) ◽

pp. 5461 ◽

Cited By ~ 1

Author(s):

Alain Küng ◽

Benjamin A. Bircher ◽

Felix Meli

Keyword(s):

Measurement System ◽

Degrees Of Freedom ◽

Low Cost ◽

Complementary Metal Oxide Semiconductor ◽

Cmos Image Sensor ◽

Image Sensor ◽

Oxide Semiconductor ◽

Measurement Systems ◽

Starting Point ◽

Sensor Properties

Accurate traceable measurement systems often use laser interferometers for position measurements in one or more dimensions. Since interferometers provide only incremental information, they are often combined with index sensors to provide a stable reference starting point. Straightness measurements are important for machine axis correction and for systems having several degrees of freedom. In this paper, we investigate the accuracy of an optical two-dimensional (2D) index sensor, which can also be used in a straightness measurement system, based on a fiber-coupled, collimated laser beam pointing onto an image sensor. Additionally, the sensor can directly determine a 2D position over a range of a few millimeters. The device is based on a simple and low-cost complementary metal–oxide–semiconductor (CMOS) image sensor chip and provides sub-micrometer accuracy. The system is an interesting alternative to standard techniques and can even be implemented on machines for real-time corrections. This paper presents the developed sensor properties for various applications and introduces a novel error separation method for straightness measurements.

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Analysis of Disparity Information for Depth Extraction Using CMOS Image Sensor with Offset Pixel Aperture Technique

Sensors ◽

10.3390/s19030472 ◽

2019 ◽

Vol 19 (3) ◽

pp. 472 ◽

Cited By ~ 5

Author(s):

Byoung-Soo Choi ◽

Jimin Lee ◽

Sang-Hwan Kim ◽

Seunghyuk Chang ◽

JongHo Park ◽

...

Keyword(s):

Geometric Model ◽

Complementary Metal Oxide Semiconductor ◽

Cmos Image Sensor ◽

Color Pattern ◽

Image Sensor ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

Color Information ◽

Depth Extraction ◽

Measurement Results

A complementary metal oxide semiconductor (CMOS) image sensor (CIS), using offset pixel aperture (OPA) technique, was designed and fabricated using the 0.11-µm CIS process. In conventional cameras, an aperture is located on the camera lens. However, in a CIS camera using OPA technique, apertures are integrated as left-offset pixel apertures (LOPAs) and right-offset pixel apertures (ROPAs). A color pattern is built, comprising LOPA, blue, red, green, and ROPA pixels. The disparity information can be acquired from the LOPA and ROPA channels. Both disparity information and two-dimensional (2D) color information can be simultaneously acquired from the LOPA, blue, red, green, and ROPA channels. A geometric model of the OPA technique is constructed to estimate the disparity of the image, and the measurement results are compared with the estimated results. Depth extraction is thus achieved by a single CIS using the OPA technique, which can be easily adapted to commercial CIS cameras.

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Reduction of Fluorine Diffusion and Improvement of Dark Current Using Carbon Implantation in CMOS Image Sensor

Crystals ◽

10.3390/cryst11091106 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1106

Author(s):

Su-Young Chai ◽

Sung-Hoon Choa

Keyword(s):

Dark Current ◽

Complementary Metal Oxide Semiconductor ◽

Cmos Image Sensor ◽

Image Sensor ◽

State Density ◽

Oxide Semiconductor ◽

Fluorine Concentration ◽

Current Characteristics ◽

Minority Carriers

Recently, the demand of a high resolution complementary metal-oxide semiconductor (CMOS) image sensor is dramatically increasing. As the pixel size reduces to submicron, however, the quality of the sensor image decreases. In particular, the dark current can act as a large noise source resulting in reduction of the quality of the sensor image. Fluorine ion implantation was commonly used to improve the dark current by reducing the trap state density. However, the implanted fluorine diffused to the outside of the silicon surface and disappeared after annealing process. In this paper, we analyzed the effects of carbon implantation on the fluorine diffusion and the dark current characteristics of the CMOS image sensor. As the carbon was implanted with dose of 5.0 × 1014 and 1 × 1015 ions/cm2 in N+ area of FD region, the retained dose of fluorine was improved by more than 131% and 242%, respectively than no carbon implantation indicating that the higher concentration of the carbon implantation, the higher the retained dose of fluorine after annealing. As the retained fluorine concentration increased, the minority carriers of electrons or holes decreased by more Si-F bond formation, resulting in increasing the sheet resistance. When carbon was implanted with 1.0 × 1015 ions/cm2, the defective pixel, dark current, transient noise, and flicker were much improved by 25%, 9.4%, 1%, and 28%, respectively compared to no carbon implantation. Therefore, the diffusion of fluorine after annealing could be improved by the carbon implantation leading to improvement of the dark current characteristics.

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A Highly Linear CMOS Image Sensor Design Based on an Adaptive Nonlinear Ramp Generator and Fully Differential Pipeline Sampling Quantization with a Double Auto-Zeroing Technique

Sensors ◽

10.3390/s20041046 ◽

2020 ◽

Vol 20 (4) ◽

pp. 1046

Author(s):

Chuangze Li ◽

Benguang Han ◽

Jie He ◽

Zhongjie Guo ◽

Longsheng Wu

Keyword(s):

Complementary Metal Oxide Semiconductor ◽

Cmos Image Sensor ◽

Image Sensor ◽

Frame Rate ◽

Oxide Semiconductor ◽

Ramp Generator ◽

Fully Differential ◽

Generator Circuit ◽

Pattern Noise ◽

Fixed Pattern Noise

For a complementary metal-oxide-semiconductor image sensor with highly linear, low noise and high frame rate, the nonlinear correction and frame rate improvement techniques are becoming very important. The in-pixel source follower transistor and the integration capacitor on the floating diffusion node cause linearity degradation. In order to address this problem, this paper proposes an adaptive nonlinear ramp generator circuit based on dummy pixels used in single-slope analog-to-digital converter topology for a complementary metal-oxide-semiconductor (CMOS) image sensor. In the proposed approach, the traditional linear ramp generator circuit is replaced with the new proposed adaptive nonlinear ramp generator circuit that can mitigate the nonlinearity of the pixel unit circuit, especially the gain nonlinearity of the source follower transistor and the integration capacitor nonlinearity of the floating diffusion node. Moreover, in order to enhance the frame rate and address the issue of high column fixed pattern noise, a new readout scheme of fully differential pipeline sampling quantization with a double auto-zeroing technique is proposed. Compared with the conventional readout structure without a fully differential pipeline sampling quantization technique and double auto-zeroing technique, the proposed readout scheme cannot only enhance the frame rate but can also improve the consistency of the offset and delay information of different column comparators and significantly reduce the column fixed pattern noise. The proposed techniques are simulated and verified with a prototype chip fabricated using typical 180 nm CMOS process technology. The obtained measurement results demonstrate that the overall nonlinearity of the CMOS image sensor is reduced from 1.03% to 0.047%, the efficiency of the comparator is improved from 85.3% to 100%, and the column fixed pattern noise is reduced from 0.43% to 0.019%.

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Optofluidic Formaldehyde Sensing: Towards On-Chip Integration

Micromachines ◽

10.3390/mi11070673 ◽

2020 ◽

Vol 11 (7) ◽

pp. 673 ◽

Cited By ~ 2

Author(s):

Daniel Mariuta ◽

Arumugam Govindaraji ◽

Stéphane Colin ◽

Christine Barrot ◽

Stéphane Le Calvé ◽

...

Keyword(s):

Absorption Coefficient ◽

Detection System ◽

Fluorescence Emission ◽

Complementary Metal Oxide Semiconductor ◽

Image Sensor ◽

Air Pollutant ◽

Oxide Semiconductor ◽

Excitation Wavelength ◽

Formaldehyde Concentration ◽

On Chip

Formaldehyde (HCHO), a chemical compound used in the fabrication process of a broad range of household products, is present indoors as an airborne pollutant due to its high volatility caused by its low boiling point ( T = − 19 °C). Miniaturization of analytical systems towards palm-held devices has the potential to provide more efficient and more sensitive tools for real-time monitoring of this hazardous air pollutant. This work presents the initial steps and results of the prototyping process towards on-chip integration of HCHO sensing, based on the Hantzsch reaction coupled to the fluorescence optical sensing methodology. This challenge was divided into two individually addressed problems: (1) efficient airborne HCHO trapping into a microfluidic context and (2) 3,5–diacetyl-1,4-dihydrolutidine (DDL) molecular sensing in low interrogation volumes. Part (2) was addressed in this paper by proposing, fabricating, and testing a fluorescence detection system based on an ultra-low light Complementary metal-oxide-semiconductor (CMOS) image sensor. Two three-layer fluidic cell configurations (quartz–SU-8–quartz and silicon–SU-8–quartz) were tested, with both possessing a 3.5 µL interrogation volume. Finally, the CMOS-based fluorescence system proved the capability to detect an initial 10 µg/L formaldehyde concentration fully derivatized into DDL for both the quartz and silicon fluidic cells, but with a higher signal-to-noise ratio (SNR) for the silicon fluidic cell ( S N R s i l i c o n = 6.1 ) when compared to the quartz fluidic cell ( S N R q u a r t z = 4.9 ). The signal intensity enhancement in the silicon fluidic cell was mainly due to the silicon absorption coefficient at the excitation wavelength, a ( λ a b s = 420 nm ) = 5 × 10 4 cm − 1 , which is approximately five times higher than the absorption coefficient at the fluorescence emission wavelength, a ( λ e m = 515 nm ) = 9.25 × 10 3 cm − 1 .

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Polarization Analyzing Image Sensor with On-Chip Metal Wire Grid Polarizer in 65-nm Standard Complementary Metal Oxide Semiconductor Process

Japanese Journal of Applied Physics ◽

10.1143/jjap.50.04dl01 ◽

2011 ◽

Vol 50 (4) ◽

pp. 04DL01 ◽

Cited By ~ 18

Author(s):

Sanshiro Shishido ◽

Toshihiko Noda ◽

Kiyotaka Sasagawa ◽

Takashi Tokuda ◽

Jun Ohta

Keyword(s):

Metal Oxide ◽

Complementary Metal Oxide Semiconductor ◽

Image Sensor ◽

Metal Oxide Semiconductor ◽

Metal Wire ◽

Oxide Semiconductor ◽

Wire Grid ◽

On Chip ◽

Wire Grid Polarizer ◽

Semiconductor Process

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Complementary Metal-Oxide Semiconductor (CMOS) Image Sensor: An Insight as a Point-of-Care Label-Free Immunosensor

Analytical Sciences ◽

10.2116/analsci.26.1215 ◽

2010 ◽

Vol 26 (12) ◽

pp. 1215-1217 ◽

Cited By ~ 9

Author(s):

Karthikeyan KANDASAMY ◽

Mohana MARIMUTHU ◽

Gun Yong SUNG ◽

Chang Geun AHN ◽

Sanghyo KIM

Keyword(s):

Metal Oxide ◽

Point Of Care ◽

Complementary Metal Oxide Semiconductor ◽

Cmos Image Sensor ◽

Image Sensor ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

Label Free

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DENOISING ALGORITHM FOR THE PIXEL-RESPONSE NON-UNIFORMITY CORRECTION OF A SCIENTIFIC CMOS UNDER LOW LIGHT CONDITIONS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xli-b3-749-2016 ◽

2016 ◽

Vol XLI-B3 ◽

pp. 749-753 ◽

Cited By ~ 1

Author(s):

Changmiao Hu ◽

Yang Bai ◽

Ping Tang

Keyword(s):

Imaging System ◽

Complementary Metal Oxide Semiconductor ◽

Cmos Image Sensor ◽

Image Sensor ◽

Oxide Semiconductor ◽

Integrating Sphere ◽

Light Conditions ◽

Low Light ◽

Spatial Uniformity ◽

High Level

We present a denoising algorithm for the pixel-response non-uniformity correction of a scientific complementary metal–oxide–semiconductor (CMOS) image sensor, which captures images under extremely low-light conditions. By analyzing the integrating sphere experimental data, we present a pixel-by-pixel flat-field denoising algorithm to remove this fixed pattern noise, which occur in low-light conditions and high pixel response readouts. The response of the CMOS image sensor imaging system to the uniform radiance field shows a high level of spatial uniformity after the denoising algorithm has been applied.

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