Nana Akahane

Bio: Nana Akahane is an academic researcher from Tohoku University. The author has contributed to research in topics: Image sensor & Photodiode. The author has an hindex of 14, co-authored 38 publications receiving 709 citations. Previous affiliations of Nana Akahane include Olympus Corporation.

A 100 dB dynamic range CMOS image sensor using a lateral overflow integration capacitor

Abstract: The wide DR CMOS image sensor incorporates a lateral overflow capacitor in each pixel to integrate the overflow charges from the photodiode when it saturates. The 7.5/spl times/7.5 /spl mu/m/sup 2/ pixel, 1/3" VGA sensor fabricated in a 0.35 /spl mu/m 3M2P CMOS process achieves a 100 dB dynamic range with no image lag, 0.15 mV/sub rms/ random noise and 0.15 mV fixed pattern noise.

A sensitivity and linearity improvement of a 100-dB dynamic range CMOS image sensor using a lateral overflow integration capacitor

Abstract: In a CMOS image sensor featuring a lateral overflow integration capacitor in a pixel, which integrates the overflowed charges from a fully depleted photodiode during the same exposure, the sensitivity in nonsaturated signal and the linearity in saturated overflow signal have been improved by introducing a new pixel circuit and its operation. The floating diffusion capacitance of the CMOS image sensor is as small as that of a four transistors type CMOS image sensor because the lateral overflow integration capacitor is located next to the reset switch. A 1/3-inch VGA format (640/sup H//spl times/480/sup V/ pixels), 7.5/spl times/7.5 /spl mu/m/sup 2/ pixel color CMOS image sensor fabricated through 0.35-/spl mu/m two-poly three-metal CMOS process results in a 100 dB dynamic range characteristic, with improved sensitivity and linearity.

Optical Sensor, Solid-State Imaging Device, and Operating Method of Solid-State Imaging Device

Abstract: In an optical device such as an optical sensor or a solid-state imaging device having a photodiode for receiving light and producing photocharges and a transfer transistor (or an overflow gate) for transferring the photocharge, it is configured that photocharges overflowing from the photo diode in storage operation are stored into a plurality of storage capacitance elements through the transfer transistor or the overflow gate, thereby obtaining the optical device adapted to maintain a high sensitivity and a high S/N ratio and having a wide dynamic range.

A sensitivity and linearity improvement of a 100 dB dynamic range CMOS image sensor using a lateral overflow integration capacitor

Abstract: In a CMOS image sensor featuring a lateral overflow capacitor in a pixel, which integrates the overflowed charges from a frilly depleted photodiode during the same exposure, the sensitivity in non-saturated signal and the linearity in saturated overflow signal have been improved by introducing a new pixel circuit and its operation. A 1/3" VGA color CMOS image sensor has fabricated through 0.35 /spl mu/m 2P3M CMOS process results in a 100 dB dynamic range characteristic, with improved sensitivity and linearity.

A 200- $\mu$ V/e $^{-}$ CMOS Image Sensor With 100-ke $^{-}$ Full Well Capacity

Abstract: A high-sensitivity CMOS image sensor keeping a high full-well capacity has been developed by introducing a new pixel having a small floating diffusion (FD) capacitance connected to a lateral overflow integration capacitor (LOFIC) through a MOS switch. The conceptual advantage of the small FD approach over conventional column amplifier approaches is compared and demonstrated. To ensure both the high sensitivity and the high full-well capacity, the low-light and the bright-light signals (S1 and S2) are output and reproduced without a visible SNR degradation at the S1/S2 switching point. As the most critical problem, the increase of the conversion gain variation in this approach is suppressed by applying a self-aligned offset structure to the small FD. A 1/4-in VGA format CMOS image sensor fabricated through 0.18-mum 2P3M process achieves 2.2-e- rms noise floor with 200-muV/e- conversion gain and 100-ke- full-well capacity.

Solid state image pickup device and camera

Abstract: A solid state image pickup device which can prevent color mixture by using a layout of a capacitor region provided separately from a floating diffusion region and a camera using such a device are provided. A photodiode region is a rectangular region including a photodiode. A capacitor region includes a carrier holding unit and is arranged on one side of the rectangle of the photodiode region as a region having a side longer than the one side. In a MOS unit region, an output unit region including an output unit having a side longer than the other side which crosses the one side of the rectangle of the photodiode region is arranged on the other side. A gate region and the FD region are arranged between the photodiode region and the capacitor region.

Color Imaging: Fundamentals and Applications

Abstract: This book provides the reader with an understanding of what color is, where color comes from, and how color can be used correctly in many different applications. The authors first treat the physics of light and its interaction with matter at the atomic level, so that the origins of color can be appreciated. The intimate relationship between energy levels, orbital states, and electromagnetic waves helps to explain why diamonds shimmer, rubies are red, and the feathers of the Blue Jay are blue. Then, color theory is explained from its origin to the current state of the art, including image capture and display as well as the practical use of color in disciplines such as computer graphics, computer vision, photography, and film.

Solid-state imaging device and electronic apparatus

Abstract: A solid-state imaging device includes a pixel region in which shared pixels which share pixel transistors in a plurality of photoelectric conversion portions are two-dimensionally arranged. The shared pixel transistors are divisionally arranged in a column direction of the shared pixels, the pixel transistors shared between neighboring shared pixels are arranged so as to be horizontally reversed or/and vertically crossed, and connection wirings connected to a floating diffusion portion, a source of a reset transistor and a gate of an amplification transistor in the shared pixels are arranged along the column direction.

Wide-Dynamic-Range CMOS Image Sensors—Comparative Performance Analysis

Abstract: A large variety of solutions for widening the dynamic range (DR) of CMOS image sensors has been proposed throughout the years. We propose a set of criteria upon which an effective comparative analysis of the performance of wide-DR (WDR) sensors can be done. Sensors for WDR are divided into seven categories: 1) companding sensors; 2) multimode sensors; 3) clipping sensors; 4) frequency-based sensors; 5) time-to-saturation (time-to-first spike) sensors; 6) global-control-over-the-integration-time sensors; and 7) autonomous-control-over-the-integration-time sensors. The comparative analysis for each category is based upon the quantitative assessments of the following parameters: signal-to-noise ratio, DR extension, noise floor, minimal transistor count, and sensitivity. These parameters are assessed using consistent assumptions and definitions, which are common to all WDR sensor categories. The advantages and disadvantages of each category in the sense of power consumption and data rate are discussed qualitatively. The influence of technology advancements on the proposed set of criteria is discussed as well.

A sensitivity and linearity improvement of a 100-dB dynamic range CMOS image sensor using a lateral overflow integration capacitor

Abstract: In a CMOS image sensor featuring a lateral overflow integration capacitor in a pixel, which integrates the overflowed charges from a fully depleted photodiode during the same exposure, the sensitivity in nonsaturated signal and the linearity in saturated overflow signal have been improved by introducing a new pixel circuit and its operation. The floating diffusion capacitance of the CMOS image sensor is as small as that of a four transistors type CMOS image sensor because the lateral overflow integration capacitor is located next to the reset switch. A 1/3-inch VGA format (640/sup H//spl times/480/sup V/ pixels), 7.5/spl times/7.5 /spl mu/m/sup 2/ pixel color CMOS image sensor fabricated through 0.35-/spl mu/m two-poly three-metal CMOS process results in a 100 dB dynamic range characteristic, with improved sensitivity and linearity.