CMOS image sensors: electronic camera-on-a-chip
TL;DR: In this article, the requirements for CMOS image sensors and their historical development, CMOS devices and circuits for pixels, analog signal chain, and on-chip analog-to-digital conversion are reviewed and discussed.
Abstract: CMOS active pixel sensors (APS) have performance competitive with charge-coupled device (CCD) technology, and offer advantages in on-chip functionality, system power reduction, cost, and miniaturization. This paper discusses the requirements for CMOS image sensors and their historical development, CMOS devices and circuits for pixels, analog signal chain, and on-chip analog-to-digital conversion are reviewed and discussed.
Citations
More filters
Patent•
08 Mar 2001TL;DR: In this paper, a system and method for obtaining in-vivo images is presented, which contains an imaging system and an ultra low power radio frequency transmitter for transmitting signals from the CMOS imaging camera to a receiving system located outside a patient.
Abstract: The present invention provides a system and method for obtaining in vivo images. The system contains an imaging system and an ultra low power radio frequency transmitter for transmitting signals from the CMOS imaging camera to a receiving system located outside a patient. The imaging system includes at least one CMOS imaging camera, at least one illumination source for illuminating an in vivo site and an optical system for imaging the in vivo site onto the CMOS imaging camera.
304 citations
TL;DR: Event cameras as discussed by the authors are bio-inspired sensors that differ from conventional frame cameras: instead of capturing images at a fixed rate, they asynchronously measure per-pixel brightness changes, and output a stream of events that encode the time, location and sign of the brightness changes.
Abstract: Event cameras are bio-inspired sensors that differ from conventional frame cameras: Instead of capturing images at a fixed rate, they asynchronously measure per-pixel brightness changes, and output a stream of events that encode the time, location and sign of the brightness changes. Event cameras offer attractive properties compared to traditional cameras: high temporal resolution (in the order of μs), very high dynamic range (140 dB versus 60 dB), low power consumption, and high pixel bandwidth (on the order of kHz) resulting in reduced motion blur. Hence, event cameras have a large potential for robotics and computer vision in challenging scenarios for traditional cameras, such as low-latency, high speed, and high dynamic range. However, novel methods are required to process the unconventional output of these sensors in order to unlock their potential. This paper provides a comprehensive overview of the emerging field of event-based vision, with a focus on the applications and the algorithms developed to unlock the outstanding properties of event cameras. We present event cameras from their working principle, the actual sensors that are available and the tasks that they have been used for, from low-level vision (feature detection and tracking, optic flow, etc.) to high-level vision (reconstruction, segmentation, recognition). We also discuss the techniques developed to process events, including learning-based techniques, as well as specialized processors for these novel sensors, such as spiking neural networks. Additionally, we highlight the challenges that remain to be tackled and the opportunities that lie ahead in the search for a more efficient, bio-inspired way for machines to perceive and interact with the world.
277 citations
Patent•
11 Jul 1997TL;DR: In this article, the removal of VLSI circuits from silicon wafers and mounting of the circuits on application specific substrates is used to provide highly flexible and ultra-thin devices having a variety of applications.
Abstract: Integrated circuits for use in electronic devices requiring high density packaging are fabricated to provide highly flexible and ultra-thin devices having a variety of applications. The flexible circuits have dimensions up to several centimeters in surface area and thicknesses of a few microns. These circuits are fabricated using transfer techniques which include the removal of VLSI circuits from silicon wafers and mounting of the circuits on application specific substrates.
260 citations
TL;DR: Here, perovskite thin-single-crystal (TSC) photodetectors are fabricated with a vertical p-i-n structure, which reduces charge recombination and enables a linear response under strong light, superior to polycrystalline photodETectors.
Abstract: Organic-inorganic halide perovskites are promising photodetector materials due to their strong absorption, large carrier mobility, and easily tunable bandgap. Up to now, perovskite photodetectors are mainly based on polycrystalline thin films, which have some undesired properties such as large defective grain boundaries hindering the further improvement of the detector performance. Here, perovskite thin-single-crystal (TSC) photodetectors are fabricated with a vertical p-i-n structure. Due to the absence of grain-boundaries, the trap densities of TSCs are 10-100 folds lower than that of polycrystalline thin films. The photodetectors based on CH3 NH3 PbBr3 and CH3 NH3 PbI3 TSCs show low noise of 1-2 fA Hz-1/2 , yielding a high specific detectivity of 1.5 × 1013 cm Hz1/2 W-1 . The absence of grain boundaries reduces charge recombination and enables a linear response under strong light, superior to polycrystalline photodetectors. The CH3 NH3 PbBr3 photodetectors show a linear response to green light from 0.35 pW cm-2 to 2.1 W cm-2 , corresponding to a linear dynamic range of 256 dB.
257 citations
03 Aug 2010
TL;DR: This paper reviews the rationale and history of this event-based approach, introduces sensor functionalities, and gives an overview of the papers in this session.
Abstract: The four chips [1–4] presented in the special session on "Activity-driven, event-based vision sensors" quickly output compressed digital data in the form of events. These sensors reduce redundancy and latency and increase dynamic range compared with conventional imagers. The digital sensor output is easily interfaced to conventional digital post processing, where it reduces the latency and cost of post processing compared to imagers. The asynchronous data could spawn a new area of DSP that breaks from conventional Nyquist rate signal processing. This paper reviews the rationale and history of this event-based approach, introduces sensor functionalities, and gives an overview of the papers in this session. The paper concludes with a brief discussion on open questions.
237 citations
References
More filters
TL;DR: A new semiconductor device concept that consists of storing charge in potential wells created at the surface of a semiconductor and moving the charge over the surface by moving the potential minima is described.
Abstract: In this paper we describe a new semiconductor device concept. Basically, it consists of storing charge in potential wells created at the surface of a semiconductor and moving the charge (representing information) over the surface by moving the potential minima. We discuss schemes for creating, transferring, and detecting the presence or absence of the charge. In particular, we consider minority carrier charge storage at the Si-SiO 2 interface of a MOS capacitor. This charge may be transferred to a closely adjacent capacitor on the same substrate by appropriate manipulation of electrode potentials. Examples of possible applications are as a shift register, as an imaging device, as a display device, and in performing logic.
878 citations
Journal Article•
TL;DR: In this article, the requirements for CMOS image sensors and their historical development, CMOS devices and circuits for pixels, analog signal chain, and on-chip analog-to-digital conversion are reviewed and discussed.
Abstract: CMOS active pixel sensors (APS) have performance competitive with charge-coupled device (CCD) technology, and offer advantages in on-chip functionality, system power reduction, cost, and miniaturization. This paper discusses the requirements for CMOS image sensors and their historical development, CMOS devices and circuits for pixels, analog signal chain, and on-chip analog-to-digital conversion are reviewed and discussed.
693 citations
TL;DR: In this paper, a family of CMOS-based active pixel image sensors (APSs) that are inherently compatible with the integration of on-chip signal processing circuitry is reported.
Abstract: A family of CMOS-based active pixel image sensors (APSs) that are inherently compatible with the integration of on-chip signal processing circuitry is reported. The image sensors were fabricated using commercially available 2-/spl mu/m CMOS processes and both p-well and n-well implementations were explored. The arrays feature random access, 5-V operation and transistor-transistor logic (TTL) compatible control signals. Methods of on-chip suppression of fixed pattern noise to less than 0.1% saturation are demonstrated. The baseline design achieved a pixel size of 40 /spl mu/m/spl times/40 /spl mu/m with 26% fill-factor. Array sizes of 28/spl times/28 elements and 128/spl times/128 elements have been fabricated and characterized. Typical output conversion gain is 3.7 /spl mu/V/e/sup -/ for the p-well devices and 6.5 /spl mu/V/e/sup -/ for the n-well devices. Input referred read noise of 28 e/sup -/ rms corresponding to a dynamic range of 76 dB was achieved. Characterization of various photogate pixel designs and a photodiode design is reported. Photoresponse variations for different pixel designs are discussed.
532 citations
"CMOS image sensors: electronic came..." refers background in this paper
...The photogate APS was introduced by JPL in 1993 [53]‐[ 55 ] for high-performance scientific imaging and lowlight applications....
[...]
12 Jul 1993
TL;DR: ActivePixel Sensor (APS) as mentioned in this paper is a detector array technology that has at least one active transistor within the pixel unit cell, which eliminates the need for nearly perfect charge transfer, which makes CCD's radiation'soft' and difficult to use under low light conditions, difficult to integrate with on-chip electronics, difficulty to use at low temperatures, and difficulty to manufacture in non-silicon materials that extend wavelength response.
Abstract: Charge-coupled devices (CCDs) are presently the technology of choice for most imaging applications. In the 23 years since their invention in 1970, they have evolved to a sophisticated level of performance. However, as with all technologies, we can be certain that they will be supplanted someday. In this paper, the Active Pixel Sensor (APS) technology is explored as a possible successor to the CCD. An active pixel is defined as a detector array technology that has at least one active transistor within the pixel unit cell. The APS eliminates the need for nearly perfect charge transfer--the Achilles' heel of CCDs. This perfect charge transfer makes CCD's radiation 'soft,' difficult to use under low light conditions, difficult to manufacture in large array sizes, difficult to integrate with on-chip electronics, difficult to use at low temperatures, difficult to use at high frame rates, and difficult to manufacture in non-silicon materials that extend wavelength response. With the active pixel, the signal is driven from the pixel over metallic wires rather than being physically transported in the semiconductor. This paper makes a case for the development of APS technology. The state of the art is reviewed and the application of APS technology to future space-based scientific sensor systems is addressed.
457 citations
TL;DR: In this paper, a 2.0 /spl mu/m double-poly, double-metal foundry CMOS active pixel image sensor is reported, which uses TTL compatible voltages, low noise and large dynamic range, and is useful in machine vision and smart sensor applications.
Abstract: A new CMOS active pixel image sensor is reported. The sensor uses a 2.0 /spl mu/m double-poly, double-metal foundry CMOS process and is realized as a 128/spl times/128 array of 40 /spl mu/m/spl times/40 /spl mu/m pixels. The sensor features TTL compatible voltages, low noise and large dynamic range, and will be useful in machine vision and smart sensor applications. >
302 citations