57 results on '"Min-Woong Seo"'
Search Results
2. A Time-Resolved NIR Lock-In Pixel CMOS Image Sensor With Background Cancelling Capability for Remote Heart Rate Detection
- Author
-
Norimichi Tsumura, Shoji Kawahito, Tomohiko Kosugi, Yuya Shirakawa, Nobukazu Teranishi, Keita Yasutomi, Min-Woong Seo, Satoshi Aoyama, Sung-Wook Jun, Leyi Tan, Chen Cao, and Keiichiro Kagawa
- Subjects
Physics ,Brightness ,Pixel ,business.industry ,020208 electrical & electronic engineering ,02 engineering and technology ,Optics ,Modulation ,Logic gate ,0202 electrical engineering, electronic engineering, information engineering ,Sensitivity (control systems) ,Electric potential ,Electrical and Electronic Engineering ,Image sensor ,business ,Image resolution - Abstract
This paper presents a time-resolved (TR) CMOS image sensor (CIS) using two-tap near-infrared (NIR) lock-in pixels with background light (BGL) cancelling capability for remote heart rate (HR) detection. Aimed to the application, the sensor features a 1024 (V) $\times $ 1280 (H) spatial resolution with 412 (V) $\times $ 1280 (H) region-of-interest-readout (ROI-readout) at 30 fps, a high sensitivity of 134.8 ke−/lux $\cdot $ s, and an ultra-low temporal random noise of 1.13 $\mathrm {e}_{\mathrm {rms}}^{\mathrm {-}}$ at analog gain of 64. A maximum charge modulation ratio of 90.1% is obtained for realizing lock-in operation by means of in-pixel lateral electric field charge modulator (LEFM). The remote HR detection is achieved by capturing the heart-beat-induced temporal variation of the oxy-hemoglobin (HbO2) concentration by the developed TR CIS with NIR lock-in technique, and larger than 98% detection accuracies are attained under both non-visible-light condition and fluctuant brightness ambient-light environments. This remarkable feature demonstrates the superiority of the proposed method for driver monitoring applications in particular.
- Published
- 2019
3. Design and analysis on low-power and low-noise single slope ADC for digital pixel sensors
- Author
-
Hyun-Yong Jung, Myonglae Chu, Min-Woong Seo, Suksan Kim, Jiyoun Song, Sang-Gwon Lee, Sung-Jae Byun, Minkyung Kim, Daehee Bae, Junan Lee, Sung-Yong Kim, Jongyeon Lee, Jonghyun Go, Jae-kyu Lee, Chang-Rok Moon, and Hyoung-Sub Kim
- Published
- 2022
4. Gradient band gap engineered alloyed quaternary/ternary CdZnSeS/ZnSeS quantum dots: an ultrasensitive fluorescence reporter in a conjugated molecular beacon system for the biosensing of influenza virus RNA
- Author
-
Enoch Y. Park, Min-Woong Seo, Oluwasesan Adegoke, Tatsuya Kato, and Shoji Kawahito
- Subjects
Photoluminescence ,Materials science ,Band gap ,Biomedical Engineering ,Analytical chemistry ,02 engineering and technology ,General Chemistry ,General Medicine ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,Lattice constant ,Nanocrystal ,Quantum dot ,General Materials Science ,0210 nano-technology ,Ternary operation ,Biosensor - Abstract
Controlling and engineering the particle composition of semiconductor alloys is one of the topmost targets in the field of semiconductor materials science and technology. Quantum dot (QD) nanocrystals offer an unmatched opportunity to obtain a wide range of composition-controlled alloys and have captivated a great deal of interest recently. Herein, we report on band gap engineering via tuning and controlling the sulphur molar fraction (ternary shell layer) of quaternary/ternary core/shell alloyed CdZnSeS/ZnSeS QDs. Varying optical properties were exhibited by the alloyed QDs but a uniform particle size distribution was maintained across all the compositions. The alloyed QDs displayed bright emission colours under UV irradiation, whereas the photoluminescence quantum yields (PL QY) were in a remarkable range of 36–98%. Non-linearity of the lattice parameter was an indication of gradient alloying of the nanocrystals, whereas the kinetics of the optical properties unravelled the effect of intrinsic optical bowing. Displacement of bond length and anion mismatch influenced the optical properties of the QDs with respect to the variation in the PL QY. Alloyed CdZnSeS/ZnSe1.0S1.3 QDs with a spectacular PL QY were exploited as an ultrasensitive fluorescence reporter in a conjugated molecular beacon (MB) assay to detect influenza virus H1N1 RNA. Our detection system was rapid and highly sensitive for detecting extremely low concentrations of H1N1 RNA (down to 2 copies per mL), specific and versatile (detects H1N1 RNA in human serum). For proof of concept, the alloyed CdZnSeS/ZnSe1.0S1.3 QD-MB bioprobe exhibited a superior 12-fold sensitivity over an alloyed CdZnSeS-MB probe, while a conventional CdSe/ZnS-MB probe could not detect extremely low concentrations of influenza virus H1N1 RNA.
- Published
- 2020
5. A Time-Resolved Four-Tap Lock-In Pixel CMOS Image Sensor for Real-Time Fluorescence Lifetime Imaging Microscopy
- Author
-
Shoji Kawahito, Min-Woong Seo, Yoshimasa Kawata, Keita Yasutomi, Keiichiro Kagawa, and Yuya Shirakawa
- Subjects
010302 applied physics ,Fluorescence-lifetime imaging microscopy ,Materials science ,Pixel ,business.industry ,Pulse generator ,020208 electrical & electronic engineering ,02 engineering and technology ,01 natural sciences ,Optics ,Signal-to-noise ratio ,CMOS ,Logic gate ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Medical imaging ,Electrical and Electronic Engineering ,Image sensor ,business - Abstract
A programmable sub-nanosecond time-gated four-tap CMOS lock-in pixel (LIP) image sensor that uses an in-pixel pulse generator (PG) is developed for time-resolved (TR) biomedical imaging applications, such as a fluorescence lifetime imaging microscopy (FLIM). We demonstrate the system’s effectiveness with simulations and measurements. Using pixel-level PG circuits, very narrow time windows (TWs) that are less than 0.8 ns can be used for charge modulation. This rapid gating allows very weak signals from living cells to be captured with a high signal-to-noise ratio (SNR). The prototype CMOS imaging system displays a fast intrinsic response of 170 ps at 472 nm and a very low temporal random noise of 0.85 e-rms at 45 frames/s under truly correlated-double-sampling operation using two-stage charge transfer. Four outputs from the LIPs allow real-time fluorescence lifetimes (FLTs) measurement, even from samples with multiple FLT components.
- Published
- 2018
6. [Papers] Separation of Multi-path Components in Sweep-less Time-of-flight Depth Imaging with a Temporally-compressive Multi-aperture Image Sensor
- Author
-
Min-Woong Seo, Shoji Kawahito, Futa Mochizuki, Bo Zhang, Taishi Takasawa, Keita Yasutomi, Keiichiro Kagawa, and Ryota Miyagi
- Subjects
business.industry ,Aperture ,Computer science ,020208 electrical & electronic engineering ,Separation (aeronautics) ,020207 software engineering ,02 engineering and technology ,Computer Graphics and Computer-Aided Design ,Time of flight ,Optics ,Compressed sensing ,Depth imaging ,Signal Processing ,0202 electrical engineering, electronic engineering, information engineering ,Media Technology ,Multi path ,Image sensor ,business - Published
- 2018
7. 3. Ultra-Low-Noise CMOS Image Sensor with Reset-Gate-Less Pixel
- Author
-
Min-Woong Seo and Shoji Kawahito
- Subjects
Pixel ,Computer science ,business.industry ,Media Technology ,Electrical engineering ,Electrical and Electronic Engineering ,Image sensor ,business ,Reset (computing) ,Computer Science Applications ,Low noise - Published
- 2018
8. A 7 ke-SD-FWC 1.2 e-RMS Temporal Random Noise 128×256 Time-Resolved CMOS Image Sensor With Two In-Pixel SDs for Biomedical Applications
- Author
-
Shoji Kawahito and Min-Woong Seo
- Subjects
010302 applied physics ,Physics ,Correlated double sampling ,Pixel ,020208 electrical & electronic engineering ,Biomedical Engineering ,Charge (physics) ,Biosensing Techniques ,Equipment Design ,02 engineering and technology ,01 natural sciences ,Photodiode ,law.invention ,Semiconductors ,law ,Electric field ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Sensitivity (control systems) ,Electrical and Electronic Engineering ,Atomic physics ,Image sensor ,Diode - Abstract
A large full well capacity (FWC) for wide signal detection range and low temporal random noise for high sensitivity lock-in pixel CMOS image sensor (CIS) embedded with two in-pixel storage diodes (SDs) has been developed and presented in this paper. For fast charge transfer from photodiode to SDs, a lateral electric field charge modulator (LEFM) is used for the developed lock-in pixel. As a result, the time-resolved CIS achieves a very large SD-FWC of approximately 7ke-, low temporal random noise of 1.2e-rms at 20 fps with true correlated double sampling operation and fast intrinsic response less than 500 ps at 635 nm. The proposed imager has an effective pixel array of ${\text{128}}{\text{(H)}}\times {\text{256}}{\text{(V)}}$ and a pixel size of ${\text{11.2}}\times {\text{11.2}}\, \mu {\text{m}}^{2}$ . The sensor chip is fabricated by Dongbu HiTek 1P4M 0.11 $\mu {\text{m}}$ CIS process.
- Published
- 2017
9. RTS and photon shot noise reduction based on maximum likelihood estimate with multi-aperture optics and semi-photon-counting-level CMOS image sensors
- Author
-
Takashi Komuro, Bo Zhang, Shoji Kawahito, Haruki Ishida, Taishi Takasawa, Keita Yasutomi, Min-Woong Seo, and Keiichiro Kagawa
- Subjects
Reduction (complexity) ,Physics ,Photon ,Optics ,CMOS ,Aperture ,business.industry ,Image noise ,Shot noise ,Image sensor ,business ,Photon counting - Published
- 2017
10. ISSCC 2017 Report
- Author
-
Min-Woong Seo
- Subjects
Media Technology ,Electrical and Electronic Engineering ,Computer Science Applications - Published
- 2017
11. A Wide Dynamic Range CMOS Image Sensor with a Charge Splitting Gate and Two Storage Diodes
- Author
-
Shoji Kawahito, Ju-Yeong Kim, Keita Yasutomi, Minho Lee, Min-Woong Seo, Keiichiro Kagawa, and Jang-Kyoo Shin
- Subjects
Materials science ,charge splitting gate (SG) ,02 engineering and technology ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,Signal ,Article ,Analytical Chemistry ,law.invention ,law ,0103 physical sciences ,Wide dynamic range ,0202 electrical engineering, electronic engineering, information engineering ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Image sensor ,storage diode ,Instrumentation ,high- and low-sensitivity ,Diode ,010302 applied physics ,Photocurrent ,wide dynamic range (WDR) ,business.industry ,Dynamic range ,020208 electrical & electronic engineering ,Atomic and Molecular Physics, and Optics ,Photodiode ,CMOS image sensor ,Optoelectronics ,business ,Sensitivity (electronics) - Abstract
In this paper, a wide dynamic range (WDR) CMOS image sensor (CIS) with a charge splitting gate (SG) and two storage diodes (SDs) is presented. By using single-gate on/off control with the SG, photocurrent path to the first (SD1) or second storage diodes (SD2) is switched alternatively and periodically during exposure and signal electrons generated in a photodiode (PD) are transferred to and accumulated in the SD1 or SD2. By setting a large ratio of the off-time to on-time of the SG, two different sensitivity signals, which are originated by the same photodiode, are generated and a WDR image signal is obtained. This technique has a distinct advantage on mitigating the problem of motion artifact in WDR imaging with high and low sensitivity signals and flexible dynamic control of the dynamic range. An experimental WDR CMOS image sensor with 280 (H) ×, 406 (V)-pixel array consisting of 14 sub-arrays, each of which have 20 (H) ×, 406 (V) pixels, was implemented and tested. For the SG on/off-time ratio of 30 and 279, the DR of 93 dB and 104 dB, respectively, was demonstrated. The effect of the proposed WDR imaging operation on the reduced motion artifact was experimentally confirmed.
- Published
- 2019
- Full Text
- View/download PDF
12. A 10 ps Time-Resolution CMOS Image Sensor With Two-Tap True-CDS Lock-In Pixels for Fluorescence Lifetime Imaging
- Author
-
Keita Yasutomi, Min-Woong Seo, Nobukazu Teranishi, Yoshimasa Kawata, Shoji Kawahito, Izhal Abdul Halin, Keiichiro Kagawa, and Zhuo Li
- Subjects
010302 applied physics ,Materials science ,Correlated double sampling ,Pixel ,Laser diode ,Extinction ratio ,business.industry ,020208 electrical & electronic engineering ,02 engineering and technology ,01 natural sciences ,law.invention ,CMOS ,law ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Optoelectronics ,Electrical and Electronic Engineering ,Image sensor ,Photonics ,business ,Diode - Abstract
A CMOS lock-in pixel image sensor with embedded storage diodes and lateral electric field modulation (LEFM) of photo-generated charge is developed for fluorescence lifetime imaging. The time-resolved CMOS image sensor (CIS) with two-tap lock-in pixels achieves a very high time resolution of 10 ps when images are averaged over 30 frames, a very short intrinsic response time of 180 ps at 374 nm, and a low temporal random noise of $1.75{\text{e}}^{-}_{\text{rms}}$ with true correlated double sampling (CDS) operation. In addition, by using the LEFM and optimized process, a very high extinction ratio of approximately 94% at 472 nm laser diode is achieved. The usefulness of the proposed CIS is demonstrated for fluorescence lifetime imaging with the simulation and measurement results.
- Published
- 2016
13. Mechanical scanner-less multi-beam confocal microscope with wavefront modulation
- Author
-
Yu Takiguchi, Susumu Terakawa, Shoji Kawahito, Takashi Inoue, Min-Woong Seo, Hisayoshi Takamoto, and Keiichiro Kagawa
- Subjects
Wavefront ,Microscope ,Spatial light modulator ,Materials science ,business.industry ,Confocal ,Physics::Optics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,law.invention ,Numerical aperture ,Condensed Matter::Soft Condensed Matter ,010309 optics ,Optics ,Confocal microscopy ,law ,0103 physical sciences ,4Pi microscope ,Image sensor ,0210 nano-technology ,business - Abstract
We propose a novel full-electronically controlled laser confocal microscope in which a liquid-crystal-on-silicon spatial light modulator and a custom CMOS imaging sensor are synchronized for performing multi-beam confocal imaging. Adaptive wavefront modulation for functional multi-beam excitation can be achieved by displaying appropriate computer generated holograms on the spatial light modulator, in consideration of the numerical aperture of the focusing objective. We also adopted a custom CMOS imaging sensor to realize multi-beam confocal microscopy without any physical pinhole. The confocality of this microscope was verified by improvements in transverse and axial resolutions of fluorescent micro-beads.
- Published
- 2015
14. A 0.27e-rms Read Noise 220-μV/e-Conversion Gain Reset-Gate-Less CMOS Image Sensor With 0.11-μm CIS Process
- Author
-
Min-Woong Seo, Shoji Kawahito, Keiichiro Kagawa, and Keita Yasutomi
- Subjects
Physics ,CMOS sensor ,Pixel ,business.industry ,Electrical engineering ,Hardware_PERFORMANCEANDRELIABILITY ,Coupling (probability) ,Capacitance ,Noise (electronics) ,Electronic, Optical and Magnetic Materials ,CMOS ,Hardware_INTEGRATEDCIRCUITS ,Image noise ,Optoelectronics ,Electrical and Electronic Engineering ,Image sensor ,business ,Hardware_LOGICDESIGN - Abstract
A low temporal read noise and high conversion gain reset-gate-less CMOS image sensor (CIS) has been developed and demonstrated for the first time at photoelectron-counting-level imaging. To achieve a high pixel conversion gain without fine or special processes, the proposed pixel has two unique structures: 1) coupling capacitance between the transfer gate and floating diffusion (FD) and 2) coupling capacitance between the reset gate and FD, for removing parasitic capacitances around the FD node. As a result, a CIS with the proposed pixels is able to achieve a high pixel conversion gain of $220~\mu \text{V}/\text{e}^{ {{-}}}$ and a low read noise of 0.27e $^{-}_{\text {rms}}$ using correlated multiple-sampling-based readout circuitry.
- Published
- 2015
15. A Two-Tap NIR Lock-in Pixel CMOS Image Sensor with Background Light Cancelling Capability for Non-Contact Heart Rate Detection
- Author
-
Chen Cao, Yuya Shirakawa, Norimichi Tsumura, Leyi Tan, Nobukazu Teranishi, Keita Yasutomi, Shoji Kawahito, Keiichiro Kagawa, Satoshi Aoyama, Tomohiko Kosugi, and Min-Woong Seo
- Subjects
Physics ,Brightness ,Pixel ,Noise measurement ,business.industry ,020208 electrical & electronic engineering ,Near-infrared spectroscopy ,Charge (physics) ,02 engineering and technology ,Optics ,Modulation ,Electric field ,0202 electrical engineering, electronic engineering, information engineering ,Image sensor ,business - Abstract
A time-resolved CMOS image sensor (CIS) using two-tap near infrared (NIR) lock-in pixels with background light (BGL) cancelling capability for non-contact heart rate (HR) detection is presented. Aimed to the application, the sensor performances of $1.1\text{e}_{\text{rms}}^{-}$ temporal random noise and 90.1% maximum charge modulation ratio are achieved by using low noise readout circuit and in-pixel lateral electric field charge modulator (LEFM) techniques. The non-contact HR detection with accuracies of more than 98% is implemented by the developed sensor under both non-visible-light and fluctuant ambient-light brightness conditions. This remarkable performance indicates the superiority of the proposed technique for automotive security applications in particular.
- Published
- 2018
16. Demonstration of Noise Reduction Effect of Native Metal-Oxide-Semiconductor Field-Effect Transistor Used for CMOS Image Sensors
- Author
-
Min-Woong Seo and Shoji Kawahito
- Subjects
Electrical and Electronic Engineering ,Atomic and Molecular Physics, and Optics - Published
- 2015
17. [Paper] Low-light Color Reproduction by Selective Averaging in Multi-aperture Camera with Bayer Color-filter Low-noise CMOS Image Sensors
- Author
-
Taishi Takasawa, Keita Yasutomi, Shoji Kawahito, Min-Woong Seo, Keiichiro Kagawa, and Bo Zhang
- Subjects
Noise (signal processing) ,business.industry ,Aperture ,Computer science ,Noise reduction ,Salt-and-pepper noise ,Computer Graphics and Computer-Aided Design ,Noise floor ,Color gel ,Signal Processing ,Media Technology ,Image noise ,Computer vision ,Artificial intelligence ,Image sensor ,business - Published
- 2015
18. [Paper] A Low Noise CMOS Image Sensor with Pixel Optimization and Noise Robust Column-parallel Readout Circuits for Low-light Levels
- Author
-
Keita Yasutomi, Keiichiro Kagawa, Shoji Kawahito, and Min-Woong Seo
- Subjects
CMOS sensor ,Pixel ,Computer science ,business.industry ,Computer Graphics and Computer-Aided Design ,Column (database) ,Low noise ,Noise ,Embedded system ,Signal Processing ,Media Technology ,Electronic engineering ,Image noise ,Image sensor ,business ,Electronic circuit - Published
- 2015
19. A high performance multi-tap CMOS lock-in pixel image sensor for biomedical applications
- Author
-
Keita Yasutomi, Keiichiro Kagawa, Shoji Kawahito, Yuya Shirakawa, and Min-Woong Seo
- Subjects
010302 applied physics ,CMOS sensor ,Materials science ,Correlated double sampling ,Pixel ,business.industry ,020208 electrical & electronic engineering ,02 engineering and technology ,Chip ,01 natural sciences ,Photodiode ,law.invention ,CMOS ,law ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Optoelectronics ,Detection theory ,Image sensor ,business - Abstract
We have developed and evaluated the large full well capacity (FWC) for wide signal detection range and low temporal noise for high sensitivity lock-in pixel CMOS image sensor (CIS) embedded with two storage-diodes (SDs). In addition, for fast charge transfer from photodiode (PD) to SDs, a lateral electric field charge modulator (LEFM) is used for the developed lock-in pixel. As a result, the time-resolved CIS achieves a very large FWC of approximately 7000e-, low temporal random noise of 1.17e-rms at 45fps with true correlated double sampling (CDS) operation, and fast intrinsic response less than 500ps at 635nm. The proposed imager has an effective pixel array of 128(H)×256(V) and a pixel size of 11.2×11.2μm2. The sensor chip is fabricated by a Dongbu HiTek 1P4M 0.11μm CIS process.
- Published
- 2017
20. Design of an 8-tap CMOS lock-in pixel with lateral electric field charge modulator for highly time-resolved imaging
- Author
-
Nobukazu Teranishi, Min-Woong Seo, Keiichiro Kagawa, Shoji Kawahito, Yuya Shirakawa, and Keita Yasutomi
- Subjects
010302 applied physics ,Fluorescence-lifetime imaging microscopy ,CMOS sensor ,Pixel ,Computer science ,020208 electrical & electronic engineering ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,02 engineering and technology ,01 natural sciences ,Sample (graphics) ,Signal-to-noise ratio ,CMOS ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Image sensor - Abstract
Recently, CMOS time-resolved imaging devices are being widely used for scientific and medical applications. A fluorescence lifetime imaging microscopy (FLIM), which is a powerful analysis tool in fundamental physics as well as in the life science, is a typical application for the time-resolved imaging devices. For better time-resolution in the lock-in pixel design, a multi-tap pixel architecture is very effective and useful. In this paper, we have proposed an 8-tap CMOS lock-in pixel with lateral electric field charge modulator (LEFM) and demonstrated the effectiveness of designed pixel by CAD simulation. The proposed pixel makes possible to measure the highly time-resolved images with a high signal to noise ratio (SNR) and to observe various images of cells even if a sample has a multi-lifetime component. An 8-tap time-resolved CMOS image sensor chip is developed by 0.11μm 1P4M CIS process technology.
- Published
- 2017
21. 4.3 A programmable sub-nanosecond time-gated 4-tap lock-in pixel CMOS image sensor for real-time fluorescence lifetime imaging microscopy
- Author
-
Shoji Kawahito, Keiichiro Kagawa, Yuya Shirakawa, Keita Yasutomi, Min-Woong Seo, Yoshimasa Kawata, and Yuriko Masuda
- Subjects
Fluorescence-lifetime imaging microscopy ,Engineering ,Avalanche diode ,Pixel ,business.industry ,020208 electrical & electronic engineering ,02 engineering and technology ,Nanosecond ,01 natural sciences ,Sample (graphics) ,010309 optics ,Optics ,Logic gate ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Circuit complexity ,Image sensor ,business - Abstract
Fluorescence-based time-resolved (TR) analysis techniques are fundamental and effective methods in life science and medicine. Among others, fluorescence lifetime imaging microscopy (FLIM) is one of the representative measurement techniques for biomedical applications. Recently, advanced all-solid-state imaging devices for FLIM, e.g., a CCD with optional electron-multiplication (EM) readout, a single-photon avalanche diode (SPAD), and a TR CMOS image sensor (CIS), have been reported [1–3]. These devices can be implemented compactly in comparison with the typical FLIM systems such as a time-correlated single-photon counting (TCSPC) system [4]. However, imaging devices based on the CCD or SPAD still have some issues, including the need for specialized fabrication processes, use of higher voltages, and greater circuit complexity. The recent TR CIS with two taps in a pixel [3] shows us a way to realize real-time lifetime imaging, but the two-tap CIS has a limitation that a sample's lifetime cannot be measured in real time if the sample has multi-exponential decay components.
- Published
- 2017
22. 4.8 A 0.44e−rms read-noise 32fps 0.5Mpixel high-sensitivity RG-less-pixel CMOS image sensor using bootstrapping reset
- Author
-
Sung-Wook Jun, Tongxi Wang, Shoji Kawahito, Min-Woong Seo, and Tomoyuki Akahori
- Subjects
010302 applied physics ,Physics ,Pixel ,Noise (signal processing) ,020208 electrical & electronic engineering ,Linearity ,02 engineering and technology ,01 natural sciences ,Signal ,CMOS ,Logic gate ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Image sensor ,Image resolution - Abstract
In the past several years, CMOS image sensors (CISs) with sub-single-electron noise level, particularly, deep sub-electron read noise (less than 0.5e-rms), have been reported. Such an ultra-low noise level is realized with a reduced floating diffusion (FD) node capacitance for attaining the high pixel conversion gain (CG) [1,2], and a high-gain readout circuitry with noise-reduction capabilities [3,4]. Recently, a reset-gate-less (RGL) CMOS image sensor has been reported [5]. It shows an excellent read noise performance using an optimized pixel structure for high CG and high-gain column ADC with multiple sampling. In this technique, however, a very high pulsed voltage of approximately 25V for the FD reset is essential to cause a punch-through effect. It is not suitable for image sensors with high pixel resolution and high-speed signal readout.
- Published
- 2017
23. RTS Noise and Dark Current White Defects Reduction Using Selective Averaging Based on a Multi-Aperture System
- Author
-
Taishi Takasawa, Keita Yasutomi, Shoji Kawahito, Keiichiro Kagawa, Bo Zhang, and Min-Woong Seo
- Subjects
random telegraph signal (RTS) noise ,Aperture ,Stochastic resonance ,lcsh:Chemical technology ,Biochemistry ,Noise (electronics) ,Article ,Analytical Chemistry ,symbols.namesake ,Optics ,multi-aperture ,Image noise ,noise reduction ,dark current white defect ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Instrumentation ,Physics ,business.industry ,Noise spectral density ,Salt-and-pepper noise ,Atomic and Molecular Physics, and Optics ,Gaussian noise ,symbols ,business ,Dark current - Abstract
In extremely low-light conditions, random telegraph signal (RTS) noise and dark current white defects become visible. In this paper, a multi-aperture imaging system and selective averaging method which removes the RTS noise and the dark current white defects by minimizing the synthetic sensor noise at every pixel is proposed. In the multi-aperture imaging system, a very small synthetic F-number which is much smaller than 1.0 is achieved by increasing optical gain with multiple lenses. It is verified by simulation that the effective noise normalized by optical gain in the peak of noise histogram is reduced from 1.38e- to 0.48e- in a 3 × 3-aperture system using low-noise CMOS image sensors based on folding-integration and cyclic column ADCs. In the experiment, a prototype 3 × 3-aperture camera, where each aperture has 200 × 200 pixels and an imaging lens with a focal length of 3.0 mm and F-number of 3.0, is developed. Under a low-light condition, in which the maximum average signal is 11e- per aperture, the RTS noise and dark current white defects are removed and the peak signal-to-noise ratio (PSNR) of the image is increased by 6.3 dB.
- Published
- 2014
24. A high time-resolution two-tap CMOS lock-in pixel image sensor for time-resolved measurements and its applications
- Author
-
Keiichiro Kagawa, Keita Yasutomi, Shoji Kawahito, Min-Woong Seo, Yoshimasa Kawata, Yuya Shirakawa, and Nobukazu Teranishi
- Subjects
010302 applied physics ,Correlated double sampling ,Materials science ,Extinction ratio ,Laser diode ,Pixel ,business.industry ,020208 electrical & electronic engineering ,Response time ,02 engineering and technology ,01 natural sciences ,law.invention ,Optics ,CMOS ,law ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Image sensor ,business ,Diode - Abstract
A CMOS lock-in pixel image sensor with embedded storage diodes in a pixel and lateral electric field modulator (LEFM) is developed for time-resolved measurements such as a fluorescence lifetime imaging microscopy (FLIM) and near-infrared spectroscopy (NIRS). The time-resolved CMOS image sensor (CIS) with two-tap lock-in pixels achieves a very high time resolution of 10ps when images are averaged over 30 frames, a very short intrinsic response time of 180ps at 374nm, and a low temporal random noise of 1.75e-rms with true correlated double sampling (CDS) operation. In addition, by using the LEFM and optimized process, a very high extinction ratio of approximately 94% at 472nm laser diode is achieved. The usefulness of the proposed CIS is demonstrated by the device simulations and the measurements. Then, we confirmed that the developed imager is very suitable for the scientific applications such as a biomedical imaging and multifunctional cameras.
- Published
- 2016
25. A Low Noise Wide Dynamic Range CMOS Image Sensor With Low-Noise Transistors and 17b Column-Parallel ADCs
- Author
-
Tetsuya Iida, Taishi Takasawa, Min-Woong Seo, Keita Yasutomi, Shoji Kawahito, Takehide Sawamoto, and Tomoyuki Akahori
- Subjects
CMOS sensor ,Materials science ,Pixel ,business.industry ,Amplifier ,Native transistor ,Fixed-pattern noise ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,CMOS ,Wide dynamic range ,Hardware_INTEGRATEDCIRCUITS ,Electronic engineering ,Optoelectronics ,Electrical and Electronic Engineering ,Image sensor ,business ,Instrumentation - Abstract
An extremely low temporal noise and wide dynamic range CMOS image sensor is developed using low-noise transistors and high gray-scale resolution (17b) folding-integration/cyclic analog-to-digital converter (ADC). Two types of pixel are designed. One is a high conversion gain (HCG) pixel with removing the coupling capacitance between the transfer gate and the floating diffusion, and the other is a pixel for wide dynamic range (WDR) CMOS imager with a native transistor as a source follower amplifier. The CMOS image sensor that is in combination with the proposed pixels and the high performance column ADC has achieved a low pixel temporal noise of 1.1erms-, a wide dynamic range of 87.5 dB with the video rate operation (30 Hz) and the vertical fixed pattern noise of 1.08-μVrms. The implemented HCG CMOS imager and WDR CMOS imager using 0.18 μm technology have the pixel conversion gain of 73.2- and 22.8-μV/e-, respectively.
- Published
- 2013
26. A Low-Noise High-Dynamic-Range 17-b 1.3-Megapixel 30-fps CMOS Image Sensor With Column-Parallel Two-Stage Folding-Integration/Cyclic ADC
- Author
-
Takashi Watanabe, Tomoyuki Akahori, Takashi Iida, Takehide Sawamoto, Zheng Liu, Min-Woong Seo, Shoji Kawahito, Tomohiko Kosugi, Keigo Isobe, and Taishi Takasawa
- Subjects
Physics ,Correlated double sampling ,Sampling (signal processing) ,Noise measurement ,Pixel ,Dynamic range ,Fixed-pattern noise ,Electronic engineering ,Electrical and Electronic Engineering ,Image sensor ,High dynamic range ,Electronic, Optical and Magnetic Materials - Abstract
A 1.3-megapixel CMOS image sensor (CIS) with digital correlated double sampling and 17-b column-parallel two-stage folding-integration/cyclic analog-to-digital converters (ADCs) is developed. The image sensor has 0.021-erms- vertical fixed pattern noise, 1.2-erms- pixel temporal noise, and 85.0-dB dynamic range using 32 samplings in the folding-integration ADC mode. Despite the large number of samplings (32 times), the prototype image sensor is demonstrated at the video rate operation of 30 Hz by the new architecture of the proposed ADCs and the high-performance peripheral logic (or digital) parts using low-voltage differential signaling circuit. The developed 17-b CIS has no visible quantization noise at very low light level of 0.01 lx because of high grayscale resolution where 1LSB = 0.1-. The implemented CIS using 0.18- μm technology has the sensitivity of 20 V/lx ·s and the pixel conversion gain of 82 μV/e-.
- Published
- 2012
27. Development of low read noise high conversion gain CMOS image sensor for photon counting level imaging
- Author
-
Keita Yasutomi, Keiichiro Kagawa, Min-Woong Seo, and Shoji Kawahito
- Subjects
Physics ,CMOS sensor ,Pixel ,CMOS ,Noise (signal processing) ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Image noise ,Electronic engineering ,Image sensor ,Capacitance ,Photon counting - Abstract
A CMOS image sensor with deep sub-electron read noise and high pixel conversion gain has been developed. Its performance is recognized through image outputs from an area image sensor, confirming the capability of photoelectroncounting- level imaging. To achieve high conversion gain, the proposed pixel has special structures to reduce the parasitic capacitances around FD node. As a result, the pixel conversion gain is increased due to the optimized FD node capacitance, and the noise performance is also improved by removing two noise sources from power supply. For the first time, high contrast images from the reset-gate-less CMOS image sensor, with less than 0.3e− rms noise level, have been generated at an extremely low light level of a few electrons per pixel. In addition, the photon-counting capability of the developed CMOS imager is demonstrated by a measurement, photoelectron-counting histogram (PCH).
- Published
- 2016
28. Single-event transient imaging with an ultra-high-speed temporally compressive multi-aperture CMOS image sensor
- Author
-
Taishi Takasawa, Keita Yasutomi, Shin-ichiro Okihara, Futa Mochizuki, Bo Zhang, Keiichiro Kagawa, Min-Woong Seo, and Shoji Kawahito
- Subjects
Physics ,Pixel ,business.industry ,Aperture ,Skew ,020207 software engineering ,Image processing ,02 engineering and technology ,Iterative reconstruction ,Frame rate ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,010309 optics ,Optics ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Transient (oscillation) ,Image sensor ,business - Abstract
In the work described in this paper, an image reproduction scheme with an ultra-high-speed temporally compressive multi-aperture CMOS image sensor was demonstrated. The sensor captures an object by compressing a sequence of images with focal-plane temporally random-coded shutters, followed by reconstruction of time-resolved images. Because signals are modulated pixel-by-pixel during capturing, the maximum frame rate is defined only by the charge transfer speed and can thus be higher than those of conventional ultra-high-speed cameras. The frame rate and optical efficiency of the multi-aperture scheme are discussed. To demonstrate the proposed imaging method, a 5×3 multi-aperture image sensor was fabricated. The average rising and falling times of the shutters were 1.53 ns and 1.69 ns, respectively. The maximum skew among the shutters was 3 ns. The sensor observed plasma emission by compressing it to 15 frames, and a series of 32 images at 200 Mfps was reconstructed. In the experiment, by correcting disparities and considering temporal pixel responses, artifacts in the reconstructed images were reduced. An improvement in PSNR from 25.8 dB to 30.8 dB was confirmed in simulations.
- Published
- 2016
29. A Low-Noise High Intrascene Dynamic Range CMOS Image Sensor With a 13 to 19b Variable-Resolution Column-Parallel Folding-Integration/Cyclic ADC
- Author
-
Takashi Watanabe, Shinya Itoh, Shoji Kawahito, Takashi Iida, Min-Woong Seo, Keigo Isobe, Sungho Suh, Taishi Takasawa, and Keita Yasutomi
- Subjects
Pixel ,Computer science ,business.industry ,Dynamic range ,Electrical engineering ,Temporal noise ,Noise (electronics) ,law.invention ,Capacitor ,law ,Electronic engineering ,Electrical and Electronic Engineering ,Image sensor ,business ,Sensitivity (electronics) ,Image resolution ,High dynamic range - Abstract
A low temporal noise and high dynamic range CMOS image sensor is developed. A 1Mpixel CMOS image sensor with column-parallel folding-integration and cyclic ADCs has 80μVrms (1.2e-) temporal noise, 82 dB dynamic range using 64 samplings in the folding-integration ADC mode. Very high variable gray-scale resolution of 13b through 19b is attained by changing the number of samplings of pixel outputs. The implemented CMOS image sensor using a 0.18-μm technology has the sensitivity of 10-V/lx·s, the conversion gain of 67- μV/e-, and linear digital code range of more than 4 decades.
- Published
- 2012
30. Multi-Aperture-Based Probabilistic Noise Reduction of Random Telegraph Signal Noise and Photon Shot Noise in Semi-Photon-Counting Complementary-Metal-Oxide-Semiconductor Image Sensor
- Author
-
Haruki Ishida, Shoji Kawahito, Min-Woong Seo, Keiichiro Kagawa, Taishi Takasawa, Bo Zhang, Keita Yasutomi, and Takashi Komuro
- Subjects
Aperture ,Noise reduction ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,maximum likelihood estimation ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,Signal ,Article ,Analytical Chemistry ,Optics ,0103 physical sciences ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Image sensor ,semi-photon-counting-level CMOS image sensor ,Instrumentation ,010302 applied physics ,Physics ,noise reduction ,random telegraph signal noise ,multi-aperture camera ,Pixel ,010308 nuclear & particles physics ,business.industry ,Noise (signal processing) ,Shot noise ,Atomic and Molecular Physics, and Optics ,Photon counting ,business - Abstract
A probabilistic method to remove the random telegraph signal (RTS) noise and to increase the signal level is proposed, and was verified by simulation based on measured real sensor noise. Although semi-photon-counting-level (SPCL) ultra-low noise complementary-metal-oxide-semiconductor (CMOS) image sensors (CISs) with high conversion gain pixels have emerged, they still suffer from huge RTS noise, which is inherent to the CISs. The proposed method utilizes a multi-aperture (MA) camera that is composed of multiple sets of an SPCL CIS and a moderately fast and compact imaging lens to emulate a very fast single lens. Due to the redundancy of the MA camera, the RTS noise is removed by the maximum likelihood estimation where noise characteristics are modeled by the probability density distribution. In the proposed method, the photon shot noise is also relatively reduced because of the averaging effect, where the pixel values of all the multiple apertures are considered. An extremely low-light condition that the maximum number of electrons per aperture was the only 2 e − was simulated. PSNRs of a test image for simple averaging, selective averaging (our previous method), and the proposed method were 11.92 dB, 11.61 dB, and 13.14 dB, respectively. The selective averaging, which can remove RTS noise, was worse than the simple averaging because it ignores the pixels with RTS noise and photon shot noise was less improved. The simulation results showed that the proposed method provided the best noise reduction performance.
- Published
- 2018
31. Dynamic range expansion of active pixel sensor with output voltage feedback
- Author
-
Min-Woong Seo, Jae-Sung Kong, Jang-Kyoo Shin, and Sang-Ho Seo
- Subjects
CMOS sensor ,Engineering ,0-10 V lighting control ,Dynamic range ,business.industry ,Hardware_PERFORMANCEANDRELIABILITY ,CMOS ,Hardware_GENERAL ,Wide dynamic range ,Hardware_INTEGRATEDCIRCUITS ,Electronic engineering ,Image sensor ,business ,Voltage ,Diode - Abstract
In this paper, a wide dynamic range active pixel sensor(APS) with output voltage feedback structure has been designed by a 2-poly 4-metal 0.35 m standard CMOS technology. We presented a novel APS with output voltage feedback, which exhibits a wide dynamic range. The dynamic range increases at the cost of an additional diode and an additional MOSFET. The output voltage feedback structure enables the control of the output voltage level by itself, as incident light power varies. It is confirmed that the light level which the output voltage level of proposed APS is saturated is about 120,000 lux, which is higher than that of a conventional 3-transistor APS.
- Published
- 2009
32. Pseudo 2-transistor active pixel sensor using an n-well/gate-tied p-channel metal oxide semiconductor field eeffect transistor-type photodetector with built-in transfer gate
- Author
-
Min-Woong Seo, Jae-Sung Kong, Pyung Choi, Sang-Ho Seo, and Jang-Kyoo Shin
- Subjects
CMOS sensor ,Materials science ,business.industry ,Transistor ,Photodetector ,Hardware_PERFORMANCEANDRELIABILITY ,Atomic and Molecular Physics, and Optics ,law.invention ,Photodiode ,CMOS ,Hardware_GENERAL ,law ,MOSFET ,Hardware_INTEGRATEDCIRCUITS ,Optoelectronics ,Field-effect transistor ,business ,p–n junction ,Hardware_LOGICDESIGN - Abstract
In this paper, a pseudo 2-transistor active pixel sensor (APS) has been designed and fabricated by using an n-well/gate-tied p-channel metal oxide semiconductor field effect transistor (PMOSFET)-type photodetector with built-in transfer gate. The proposed sensor has been fabricated using a 0.35 μm 2-poly 4-metal standard complementary metal oxide semiconductor (CMOS) logic process. The pseudo 2-transistor APS consists of two NMOSFETs and one photodetector which can amplify the generated photocurrent. The area of the pseudo 2-transistor APS is 7.1 × 6.2 μm2. The sensitivity of the proposed pixel is 49 lux/(V·s). By using this pixel, a smaller pixel area and a higher level of sensitivity can be realized when compared with a conventional 3-transistor APS which uses a pn junction photodiode.
- Published
- 2008
33. Dynamic range improvement of active pixel sensor using charge pump circuit
- Author
-
Sang-Ho Seo, Kyoung-Do Kim, Jang-Kyoo Shin, and Min-Woong Seo
- Subjects
CMOS sensor ,Materials science ,Pixel ,Dynamic range ,business.industry ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Electrical engineering ,Hardware_PERFORMANCEANDRELIABILITY ,Photodiode ,law.invention ,CMOS ,law ,Wide dynamic range ,Hardware_INTEGRATEDCIRCUITS ,Charge pump ,Image sensor ,business - Abstract
Wide dynamic range active pixel sensor(APS) using a charge pump circuit has been designed by using 2-poly 4-metal standard CMOS technology. The structure of the proposed APS is similar to the structure of the conventional 3-Tr APS. The proposed unit pixel consists of one photodiode and three MOSFETs. Using a charge pump circuit, the dynamic range of the proposed APS is increased, compared to the conventional 3-Tr APS.
- Published
- 2008
34. Evaluation of dual-wavelength excitation autofluorescence imaging of colorectal tumours with a high-sensitivity CMOS imager: a cross-sectional study
- Author
-
Shinji Tanaka, Shigeto Yoshida, Shoji Kawahito, Rie Miyaki, Hidenobu Arimoto, Kenji Yamada, Yoko Kominami, Keiichiro Kagawa, Min-Woong Seo, Yoji Sanomura, and Kazuaki Chayama
- Subjects
Adenoma ,Male ,medicine.medical_specialty ,Colorectal cancer ,Tumor resection ,Dual-wavelength excitation autofluorescence image ,Colonic Polyps ,Colorectal tumour ,Adenocarcinoma ,Fluorescence ,medicine ,Humans ,Dual wavelength ,Aged ,High signal intensity ,business.industry ,Optical Imaging ,Gastroenterology ,General Medicine ,Middle Aged ,medicine.disease ,Autofluorescence ,Cross-Sectional Studies ,Technical Advance ,Semiconductors ,CMOS ,High-sensitivity CMOS imager ,Female ,Radiology ,Colorectal Neoplasms ,business ,Sensitivity (electronics) ,Sessile serrated adenoma - Abstract
Background It is important to devise efficient and easy methods of detecting colorectal tumours to reduce mortality from colorectal cancer. Dual-wavelength excitation autofluorescence intensity can be used to visualize colorectal tumours. Therefore, we evaluated dual-wavelength excitation autofluorescence images of colorectal tumours obtained with a newly developed, high-sensitivity complementary metal-oxide-semiconductor (CMOS) imager. Methods A total 107 colorectal tumours (44 adenomas, 43 adenocarcinomas with intramucosal invasion, and 20 sessile serrated adenoma/polyps [SSA/Ps]) in 98 patients who underwent endoscopic tumour resection were included. The specimens were irradiated with excitation light at 365 nm and 405 nm, and autofluorescence images measured with a 475 ± 25-nm band pass filter were obtained using a new, high-sensitivity CMOS imager. Ratio images (F365ex/F405ex) were created to evaluate the lesion brightness compared with that of normal mucosa, and specimens were categorized into a no signal or high signal group. Results Adenomas and adenocarcinomas were depicted in 87 ratio images, with 86.2 % (n = 75) in the High signal group. SSA/P was depicted in 20 ratio images, with 70.0 % (n = 14) in the High signal group. Conclusions Dual-wavelength excitation autofluorescence images of colorectal tumours can be acquired using our high-sensitivity CMOS imager, and are useful in detecting colorectal tumours.
- Published
- 2015
35. A high-sensitivity 2x2 multi-aperture color camera based on selective averaging
- Author
-
Shoji Kawahito, Min-Woong Seo, Taishi Takasawa, Bo Zhang, Keita Yasutomi, and Keiichiro Kagawa
- Subjects
Physics ,Noise ,Optics ,Dark-frame subtraction ,business.industry ,Noise reduction ,Image noise ,Image sensor ,business ,Noise floor ,Dot pitch ,Dark current - Abstract
To demonstrate the low-noise performance of the multi-aperture imaging system using a selective averaging method, an ultra-high-sensitivity multi-aperture color camera with 2×2 apertures is being developed. In low-light conditions, random telegraph signal (RTS) noise and dark current white defects become visible, which greatly degrades the quality of the image. To reduce these kinds of noise as well as to increase the number of incident photons, the multi-aperture imaging system composed of an array of lens and CMOS image sensor (CIS), and the selective averaging for minimizing the synthetic sensor noise at every pixel is utilized. It is verified by simulation that the effective noise at the peak of noise histogram is reduced from 1.44 e- to 0.73 e- in a 2×2-aperture system, where RTS noise and dark current white defects have been successfully removed. In this work, a prototype based on low-noise color sensors with 1280×1024 pixels fabricated in 0.18um CIS technology is considered. The pixel pitch is 7.1μm×7.1μm. The noise of the sensor is around 1e- based on the folding-integration and cyclic column ADCs, and the low voltage differential signaling (LVDS) is used to improve the noise immunity. The synthetic F-number of the prototype is 0.6.
- Published
- 2015
36. 6.4 Single-shot 200Mfps 5×3-aperture compressive CMOS imager
- Author
-
Taishi Takasawa, Keita Yasutomi, Shin-ichiro Okihara, Futa Mochizuki, Bo Zhang, Keiichiro Kagawa, Min-Woong Seo, and Shoji Kawahito
- Subjects
Physics ,business.industry ,Aperture ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Dissipation ,Frame rate ,Power (physics) ,Optics ,Compressed sensing ,CMOS ,Computer Science::Computer Vision and Pattern Recognition ,business ,Current density ,Voltage - Abstract
Ultra-high-speed cameras are a powerful tool for biology as well as physics and mechanics to analyze the process of ultra-high-speed phenomena. The frame rate of the state-of-the-art burst-readout ultra-high-speed silicon imagers has reached approximately 20Mfps [1,2]. To observe faster phenomena such as plasma generation in laser processing, the state of electrons in a chemical reaction, and so on, much faster cameras are desired. There are several factors that prevent the speed-up of the ultra-high-speed imager: high gate control voltages and high power dissipation for high-efficiency multi-stage charge transfer in CCD imagers, and the current density limit of the power and ground lines and RC-constant of the vertical readout lines in CMOS imagers. Computational imaging can be a promising option to break the design limit of solid-state ultra-high-speed imagers. Several dedicated CMOS imagers have been demonstrated [3,4]. This paper presents a demonstration of a single-chip ultra-high-speed multi-aperture CMOS imager based on compressive sampling. The imager performs single-shot burst-readout image acquisition at a frame rate of 200Mfps.
- Published
- 2015
37. 11.2 A 10.8ps-time-resolution 256×512 image sensor with 2-Tap true-CDS lock-in pixels for fluorescence lifetime imaging
- Author
-
Min-Woong Seo, Nobukazu Teranishi, Shoji Kawahito, Zhuo Li, Yoshimasa Kawata, Taishi Takasawa, Keiichiro Kagawa, Keita Yasutomi, and Izhal Abdul Halin
- Subjects
Physics ,Fluorescence-lifetime imaging microscopy ,Optics ,Pixel ,CMOS ,business.industry ,Logic gate ,Integrator ,Image sensor ,business ,Image resolution ,Diode - Abstract
Fluorescence lifetime imaging microscopy (FLIM), which is a nondestructive and minimally invasive manner and can therefore be applied to living cells and tissues, is a great analysis tool in fundamental physics as well as in the life sciences. Charge-coupled devices (CCDs) [1] and single-photon avalanche diodes (SPADs) [2,3] are used for time-resolved lifetime measurement. In particular, SPAD-based time-resolved imagers have a high single-photon sensitivity and good noise robustness. However, they consist of a SPAD array with pixel circuitry, time-to-digital converters (TDCs), digital integrators to amplify signals, and readout circuitry. To implement the high photon-counting rate, a large number of TDCs and digital integrators are required. The spatial resolution of the SPAD-based time-resolved imagers is limited on this account. A recently reported time-resolved CMOS imager [4] using a draining-only modulation (DOM) technique has an attractive feature that a very simple pixel structure and 2-stage charge transfer without transfer gate (TG) can be simultaneously attained. However, it has a small aperture area, a comparatively low transfer speed, and multiple outputs are a challenge.
- Published
- 2015
38. A low-noise high-sensitivity CMOS image sensor for scientific and industrial applications
- Author
-
Shoji Kawahito, Keiichiro Kagawa, Min-Woong Seo, Taishi Takasawa, and Keita Yasutomi
- Subjects
Physics ,CMOS sensor ,business.industry ,Electrical engineering ,Electronic engineering ,Image sensor ,business ,Sensitivity (electronics) ,Low noise - Published
- 2014
39. A 19-bit column-parallel folding-integration/cyclic cascaded ADC with a pre-charging technique for CMOS image sensors
- Author
-
Tongxi Wang, Min-Woong Seo, Shoji Kawahito, and Keita Yasutomi
- Subjects
010302 applied physics ,Materials science ,020208 electrical & electronic engineering ,High resolution ,02 engineering and technology ,Folding (DSP implementation) ,Condensed Matter Physics ,01 natural sciences ,Column (database) ,Electronic, Optical and Magnetic Materials ,Bit (horse) ,CMOS ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Electrical and Electronic Engineering ,Image sensor - Published
- 2017
40. A high fill-factor low dark leakage CMOS image sensor with shared-pixel design
- Author
-
Shoji Kawahito, Keita Yasutomi, Min-Woong Seo, and Keiichiro Kagawa
- Subjects
Physics ,Pixel ,business.industry ,Amplifier ,Transistor ,law.invention ,Responsivity ,law ,Shallow trench isolation ,Optoelectronics ,Image sensor ,business ,Leakage (electronics) ,Dark current - Abstract
We have developed and evaluated the high responsivity and low dark leakage CMOS image sensor with the ring-gate shared-pixel design. A ring-gate shared-pixel design with a high fill factor makes it possible to achieve the low-light imaging. As eliminating the shallow trench isolation in the proposed pixel, the dark leakage current is significantly decreased because one of major dark leakage sources is removed. By sharing the in-pixel transistors such as a reset transistor, a select transistor, and a source follower amplifier, each pixel has a high fill-factor of 43 % and high sensitivity of 144.6 ke - /lx·sec. In addition, the effective number of transistors per pixel is 1.75. The proposed imager achieved the relatively low dark leakage current of about 104.5 e - /s (median at 60°C), corresponding to a dark current density J dark_proposed of about 30 pA/cm 2 . In contrast, the conventional type test pixel has a large dark leakage current of 2450 e - /s (median at 60°C), corresponding to J dark_conventional of about 700 pA/cm 2 . Both pixels have a same pixel size of 7.5×7.5 μm 2 and are fabricated in same process.
- Published
- 2014
41. A time-resolved image sensor for tubeless streak cameras
- Author
-
Taishi Takasawa, Keita Yasutomi, Sang-Man Han, Keiichiro Kagawa, Min-Woong Seo, and Shoji Kawahito
- Subjects
Physics ,CMOS sensor ,Pixel ,business.industry ,Streak camera ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Streak ,Dot pitch ,Image sensor format ,Computer vision ,Artificial intelligence ,Image sensor ,business ,Image resolution - Abstract
This paper presents a time-resolved CMOS image sensor with draining-only modulation (DOM) pixels for tube-less streak cameras. Although the conventional streak camera has high time resolution, the device requires high voltage and bulky system due to the structure with a vacuum tube. The proposed time-resolved imager with a simple optics realize a streak camera without any vacuum tubes. The proposed image sensor has DOM pixels, a delay-based pulse generator, and a readout circuitry. The delay-based pulse generator in combination with an in-pixel logic allows us to create and to provide a short gating clock to the pixel array. A prototype time-resolved CMOS image sensor with the proposed pixel is designed and implemented using 0.11um CMOS image sensor technology. The image array has 30(Vertical) x 128(Memory length) pixels with the pixel pitch of 22.4um. .
- Published
- 2014
42. 10×10-pixel 606kS/s multi-point fluorescence correlation spectroscopy CMOS image sensor
- Author
-
Keiichiro Kagawa, Taishi Takasawa, Keita Yasutomi, Min-Woong Seo, Zhang Bo, Masataka Kinjo, Jotaro Yamamoto, Susumu Terakawa, Kaita Imai, and Shoji Kawahito
- Subjects
Microlens ,CMOS sensor ,Microscope ,Materials science ,Pixel ,business.industry ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Fluorescence correlation spectroscopy ,Chip ,Dot pitch ,law.invention ,law ,Optoelectronics ,Image sensor ,business - Abstract
To observe molecular transport in a living cell, a high-speed CMOS image sensor for multi-point fluorescence correlation spectroscopy is developed. To achieve low-noise and high-speed simultaneously, a prototype CMOS image sensor is designed based on a complete pixel-parallel architecture and multi-channel pipelined pixel readout. The prototype chip with 10×10 effective pixels is fabricated in 0.18-μm CMOS image sensor technology. The pixel pitch and the photosensitive area are 56μm and 10μm in diameter without a microlens, respectively. In the experiment, the total sampling rate of 606kS/s is achieved. The measured average random noise is 24.9LSB, which is equivalent to about 2.5 electrons in average.
- Published
- 2014
43. An ultra-high-speed compressive multi-aperture CMOS image sensor
- Author
-
Taishi Takasawa, Keita Yasutomi, Min-Woong Seo, Futa Mochizuki, Shoji Kawahito, and Keiichiro Kagawa
- Subjects
Ultra high speed ,CMOS sensor ,Materials science ,Pixel ,Aperture ,business.industry ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Astrophysics::Instrumentation and Methods for Astrophysics ,Optics ,Three dimensional imaging ,Computer Science::Computer Vision and Pattern Recognition ,Temporal resolution ,Electronic engineering ,Physics::Accelerator Physics ,Image sensor ,business ,Image resolution ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
To achieve subnano-second temporal resolution imaging, we have proposed a compressive multi-aperture high-speed image sensor. We designed a CMOS image sensor with 5×3 apertures and 64×54 pixels aperture. Temporal resolution of 10ns was confirmed experimentally.
- Published
- 2014
44. Noise Reduction Effect of Multiple-Sampling-Based Signal-Readout Circuits for Ultra-Low Noise CMOS Image Sensors
- Author
-
Shoji Kawahito and Min-Woong Seo
- Subjects
readout noise ,Physics::Instrumentation and Detectors ,Noise reduction ,02 engineering and technology ,lcsh:Chemical technology ,ultra low noise ,01 natural sciences ,Biochemistry ,Article ,Analytical Chemistry ,Sampling (signal processing) ,noise analysis ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Image noise ,Electronic engineering ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,differential averager ,Instrumentation ,010302 applied physics ,Physics ,correlated multiple sampling ,Noise temperature ,Noise measurement ,business.industry ,Noise (signal processing) ,1/f noise ,RTS noise ,020208 electrical & electronic engineering ,correlated double sampling ,Electrical engineering ,Noise floor ,Atomic and Molecular Physics, and Optics ,CMOS image sensor ,CMOS ,multiple correlated double sampling ,business - Abstract
This paper discusses the noise reduction effect of multiple-sampling-based signal readout circuits for implementing ultra-low-noise image sensors. The correlated multiple sampling (CMS) technique has recently become an important technology for high-gain column readout circuits in low-noise CMOS image sensors (CISs). This paper reveals how the column CMS circuits, together with a pixel having a high-conversion-gain charge detector and low-noise transistor, realizes deep sub-electron read noise levels based on the analysis of noise components in the signal readout chain from a pixel to the column analog-to-digital converter (ADC). The noise measurement results of experimental CISs are compared with the noise analysis and the effect of noise reduction to the sampling number is discussed at the deep sub-electron level. Images taken with three CMS gains of two, 16, and 128 show distinct advantage of image contrast for the gain of 128 (noise(median): 0.29 e−rms) when compared with the CMS gain of two (2.4 e−rms), or 16 (1.1 e−rms).
- Published
- 2016
45. A CMOS Image Sensor with High-speed Pixel-parallel Pipelined Readout Channels for Multi-point Fluorescence Correlation Spectroscopy
- Author
-
Masataka Kinjo, Shoji Kawahito, J. Yamamoto, Keiichiro Kagawa, Min-Woong Seo, Susumu Terakawa, K. Imai, Z. Bo, Taishi Takasawa, and Keita Yasutomi
- Subjects
Materials science ,Pixel ,business.industry ,Analytical chemistry ,Optoelectronics ,Fluorescence correlation spectroscopy ,Image sensor ,business ,Multi point - Published
- 2013
46. A High-Sensitivity Low Dark Current 1.75T/Pixel CMOS Image Sensor with Ring-Gate Shared-Pixel Design
- Author
-
Keita Yasutomi, Keiichiro Kagawa, Min-Woong Seo, and Shoji Kawahito
- Subjects
Physics ,Pixel ,business.industry ,Optoelectronics ,Sensitivity (control systems) ,Image sensor ,Ring (chemistry) ,business ,Dark current - Published
- 2013
47. Multi-aperture high-speed CMOS imager
- Author
-
Futa Mochiduki, Shoji Kawahito, Keita Yasutomi, Min-Woong Seo, and Keiichiro Kagawa
- Subjects
Digital electronics ,Engineering ,CMOS ,business.industry ,Aperture ,Shutter ,Spice ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Electronic engineering ,Pattern generation ,business ,Frame rate ,Image sensing - Abstract
To achieve ultra-high-speed image sensing faster than 1-giga frames per second, a multi-aperture high-speed imager is proposed. In this paper, the architecture of the imager and a design of digital circuits are presented. Basic operations of the digital circuits are verified by a fast SPICE simulator, NanoSim by Synopsys. Arbitrary shutter pattern of 128 bits and the number of repetition can be reprogrammed. A shutter pattern generation at 100 MHz is successfully verified.
- Published
- 2013
48. A custom CMOS imager for multi-beam laser scanning microscopy and an improvement of scanning speed
- Author
-
Min-Woong Seo, Keita Yasutomi, Shoji Kawahito, and Keiichiro Kagawa
- Subjects
Microlens ,Materials science ,business.industry ,Confocal ,Scanning confocal electron microscopy ,law.invention ,Full width at half maximum ,Optics ,Confocal microscopy ,law ,Microscopy ,Pinhole (optics) ,Image sensor ,business - Abstract
Multi-beam laser scanning confocal microscopy with a 256 × 256-pixel custom CMOS imager performing focal-plane pinhole effect, in which any rotating disk is not required, is demonstrated. A specimen is illuminated by 32 × 32 diffraction limited light spots whose wavelength and pitch are 532nm and 8.4 μm, respectively. The spot array is generated by a microlens array, which is scanned by two-dimensional piezo actuator according to the scanning of the image sensor. The frame rate of the prototype is 0.17 Hz, which is limited by the actuator. The confocal effect has been confirmed by comparing the axial resolution in the confocal imaging mode with that of the normal imaging mode. The axial resolution in the confocal mode measured by the full width at half maximum (FWHM) for a planar mirror was 8.9 μm, which is showed that the confocality has been achieved with the proposed CMOS image sensor. The focal-plane pinhole effect in the confocal microscopy with the proposed CMOS imager has been demonstrated at low frame rate. An improvement of the scanning speed and a CMOS imager with photo-sensitivity modulation pixels suitable for high-speed scanning are also discussed.
- Published
- 2013
49. Multi-beam confocal microscopy based on a custom image sensor with focal-plane pinhole array effect
- Author
-
Keiichiro Kagawa, Susumu Terakawa, Shoji Kawahito, Min-Woong Seo, and Keita Yasutomi
- Subjects
Materials science ,Microscopy, Confocal ,Pixel ,business.industry ,Confocal ,Beam steering ,Transducers ,Signal Processing, Computer-Assisted ,Equipment Design ,Image Enhancement ,Atomic and Molecular Physics, and Optics ,law.invention ,Equipment Failure Analysis ,Optics ,Cardinal point ,Planar ,Semiconductors ,Confocal microscopy ,law ,Pinhole (optics) ,Image sensor ,business ,Lighting - Abstract
Multi-beam confocal microscopy without any physical pinhole was demonstrated. As a key device, a custom CMOS image sensor realizing a focal-plane pinhole array effect by special pixel addressing and discarding of the unwanted photocarriers was developed. The axial resolution in the confocal mode measured by FWHM for a planar mirror was 8.9 μm, which showed that the confocality has been achieved with the proposed CMOS image sensor.
- Published
- 2013
50. A low noise wide dynamic range CMOS image sensor with low-noise transistors and 17b column-parallel ADC
- Author
-
Zheng Liu, Takehide Sawamoto, Taishi Takasawa, Tomoyuki Akahori, Min-Woong Seo, and Shoji Kawahito
- Subjects
CMOS sensor ,Materials science ,Pixel ,business.industry ,Amplifier ,Native transistor ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Hardware_PERFORMANCEANDRELIABILITY ,Noise (electronics) ,CMOS ,Wide dynamic range ,Hardware_INTEGRATEDCIRCUITS ,Electronic engineering ,Optoelectronics ,Image sensor ,business - Abstract
An extremely low temporal noise and wide dynamic range CMOS image sensor is developed using low-noise transistors and high gray-scale resolution (17b) folding-integration/cyclic ADC. Two types of pixel are designed. One is a high conversion gain (HCG) pixel with removing the coupling capacitance between the transfer gate and the floating diffusion, and the other is a pixel for wide dynamic range (WDR) CMOS imager with the native transistor as a source follower amplifier. The CMOS image sensor which is in combination with the proposed pixels and the high performance column ADC has achieved a low pixel temporal noise of 1.1e− rms and a wide dynamic range of 87.5dB with the video rate operation (30Hz). In addition, the WDR pixel has a very small occurrence of the RTS noise because of the effect of the native transistor in the pixel. The implemented HCG CMOS imager and WDR CMOS imager using 0.18μm technology have the pixel conversion gain of 73.2-μV/e− and 22.8-μV/e−, respectively.
- Published
- 2012
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.