1,078 research outputs found
Digital implementation of the cellular sensor-computers
Two different kinds of cellular sensor-processor architectures are used nowadays in various
applications. The first is the traditional sensor-processor architecture, where the sensor and the
processor arrays are mapped into each other. The second is the foveal architecture, in which a
small active fovea is navigating in a large sensor array. This second architecture is introduced
and compared here. Both of these architectures can be implemented with analog and digital
processor arrays. The efficiency of the different implementation types, depending on the used
CMOS technology, is analyzed. It turned out, that the finer the technology is, the better to use
digital implementation rather than analog
Review of ADCs for imaging
The aim of this article is to guide image sensors designers to optimize the analog-to-digital conversion of pixel outputs. The most common ADCs topologies for image sensors are presented and discussed. The ADCs specific requirements for these sensors are analyzed and quantified. Finally, we present relevant recent contributions of specific ADCs for image sensors and we compare them using a novel FOM
In-ADC, Rank-Order Filter for Digital Pixel Sensors
© 2023 The Author(s). Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/This paper presents a new implementation of the rank-order filter which is established on 10 a parallel-operated array of single-slope (SS) analogue-to-digital converters (ADCs). The SS ADCs 11 use âon-the-ramp processingâ technique i.e. filtration is performed along with analogue-to-digital 12 conversion, so the final states of the converters represent a filtered image. The proof-of-concept 13 64Ă64 array of SS ADCs, integrated with MOS photogates, was fabricated in a standard 180-nm 14 CMOS process. The measurement results demonstrate the full functionality of the novel filter 15 concept, with image acquisition in both single-sampling and correlated-double-sampling (CDS) 16 modes (the CDS is performed digitally by ADCs). The experimental, massively-parallel rank-order 17 filter can process 650 frames per second with a power consumption of 4.81 mW.Peer reviewe
Review of ADCs for imaging
The aim of this article is to guide image sensors designers to optimize the analog-to-digital conversion of pixel outputs. The most common ADCs topologies for image sensors are presented and discussed. The ADCs specific requirements for these sensors are analyzed and quantified. Finally, we present relevant recent contributions of specific ADCs for image sensors and we compare them using a novel FOM. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use onlyPeer reviewe
On evolution of CMOS image sensors
CMOS Image Sensors have become the principal technology in majority of digital cameras. They started replacing the film and Charge Coupled Devices in the last decade with the promise of lower cost, lower power requirement, higher integration and the potential of focal plane processing. However, the principal factor behind their success has been the ability to utilise the shrinkage in CMOS technology to make smaller pixels, and thereby have more resolution without increasing the cost. With the market of image sensors exploding courtesy their inte- gration with communication and computation devices, technology developers improved the CMOS processes to have better optical performance. Nevertheless, the promises of focal plane processing as well as on-chip integration have not been fulfilled. The market is still being pushed by the desire of having higher number of pixels and better image quality, however, differentiation is being difficult for any image sensor manufacturer. In the paper, we will explore potential disruptive growth directions for CMOS Image sensors and ways to achieve the same
A Review on Digital Pixel Sensors
Digital pixel sensor (DPS) has evolved as a pivotal component in modern
imaging systems and has the potential to revolutionize various fields such as
medical imaging, astronomy, surveillance, IoT devices, etc. Compared to analog
pixel sensors, the DPS offers high speed and good image quality. However, the
introduced intrinsic complexity within each pixel, primarily attributed to the
accommodation of the ADC circuit, engenders a substantial increase in the pixel
pitch. Unfortunately, such a pronounced escalation in pixel pitch drastically
undermines the feasibility of achieving high-density integration, which is an
obstacle that significantly narrows down the field of potential applications.
Nonetheless, designing compact conversion circuits along with strategic
integration of 3D architectural paradigms can be a potential remedy to the
prevailing situation. This review article presents a comprehensive overview of
the vast area of DPS technology. The operating principles, advantages, and
challenges of different types of DPS circuits have been analyzed. We categorize
the schemes into several categories based on ADC operation. A comparative study
based on different performance metrics has also been showcased for a
well-rounded understanding
Ultra-low noise, high-frame rate readout design for a 3D-stacked CMOS image sensor
Due to the switch from CCD to CMOS technology, CMOS based image sensors have become
smaller, cheaper, faster, and have recently outclassed CCDs in terms of image quality. Apart
from the extensive set of applications requiring image sensors, the next technological
breakthrough in imaging would be to consolidate and completely shift the conventional CMOS
image sensor technology to the 3D-stacked technology. Stacking is recent and an innovative
technology in the imaging field, allowing multiple silicon tiers with different functions to be
stacked on top of each other. The technology allows for an extreme parallelism of the pixel
readout circuitry. Furthermore, the readout is placed underneath the pixel array on a 3D-stacked
image sensor, and the parallelism of the readout can remain constant at any spatial resolution of
the sensors, allowing extreme low noise and a high-frame rate (design) at virtually any sensor
array resolution.
The objective of this work is the design of ultra-low noise readout circuits meant for 3D-stacked
image sensors, structured with parallel readout circuitries. The readout circuitâs key
requirements are low noise, speed, low-area (for higher parallelism), and low power.
A CMOS imaging review is presented through a short historical background, followed by the
description of the motivation, the research goals, and the work contributions. The fundamentals
of CMOS image sensors are addressed, as a part of highlighting the typical image sensor features,
the essential building blocks, types of operation, as well as their physical characteristics and their
evaluation metrics. Following up on this, the document pays attention to the readout circuitâs
noise theory and the column converters theory, to identify possible pitfalls to obtain sub-electron
noise imagers. Lastly, the fabricated test CIS device performances are reported along with
conjectures and conclusions, ending this thesis with the 3D-stacked subject issues and the future
work. A part of the developed research work is located in the Appendices.Devido à mudança da tecnologia CCD para CMOS, os sensores de imagem em CMOS tornam se mais pequenos, mais baratos, mais råpidos, e mais recentemente, ultrapassaram os sensores
CCD no que respeita à qualidade de imagem. Para além do vasto conjunto de aplicaçÔes que
requerem sensores de imagem, o prĂłximo salto tecnolĂłgico no ramo dos sensores de imagem Ă©
o de mudar completamente da tecnologia de sensores de imagem CMOS convencional para a
tecnologia â3D-stackedâ. O empilhamento de chips Ă© relativamente recente e Ă© uma tecnologia
inovadora no campo dos sensores de imagem, permitindo vĂĄrios planos de silĂcio com diferentes
funçÔes poderem ser empilhados uns sobre os outros. Esta tecnologia permite portanto, um
paralelismo extremo na leitura dos sinais vindos da matriz de pĂxeis. AlĂ©m disso, num sensor de
imagem de planos de silĂcio empilhados, os circuitos de leitura estĂŁo posicionados debaixo da
matriz de pĂxeis, sendo que dessa forma, o paralelismo pode manter-se constante para qualquer
resolução espacial, permitindo assim atingir um extremo baixo ruĂdo e um alto debito de
imagens, virtualmente para qualquer resolução desejada.
O objetivo deste trabalho Ă© o de desenhar circuitos de leitura de coluna de muito baixo ruĂdo,
planeados para serem empregues em sensores de imagem â3D-stackedâ com estruturas
altamente paralelizadas. Os requisitos chave para os circuitos de leitura sĂŁo de baixo ruĂdo,
rapidez e pouca ĂĄrea utilizada, de forma a obter-se o melhor rĂĄcio.
Uma breve revisĂŁo histĂłrica dos sensores de imagem CMOS Ă© apresentada, seguida da
motivação, dos objetivos e das contribuiçÔes feitas. Os fundamentos dos sensores de imagem
CMOS sĂŁo tambĂ©m abordados para expor as suas caracterĂsticas, os blocos essenciais, os tipos
de operação, assim como as suas caracterĂsticas fĂsicas e suas mĂ©tricas de avaliação. No
seguimento disto, especial atenção Ă© dada Ă teoria subjacente ao ruĂdo inerente dos circuitos de
leitura e dos conversores de coluna, servindo para identificar os possĂveis aspetos que dificultem
atingir a tĂŁo desejada performance de muito baixo ruĂdo. Por fim, os resultados experimentais
do sensor desenvolvido sĂŁo apresentados junto com possĂveis conjeturas e respetivas conclusĂ”es,
terminando o documento com o assunto de empilhamento vertical de camadas de silĂcio, junto
com o possĂvel trabalho futuro
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