Monday, December 11, 2017

12nm Pixel Size

There is a funny mistake in Xiaomi Redmi 5 Plus smartphone promotional video:

2-step Column-Parallel Delta-Sigma ADC

CentraleSupelec, France, publishes a paper "A 14-b Two-step Inverter-based Σ∆ ADC for CMOS Image Sensor" by Pierre Bisiaux, Caroline Lelandais-Perrault, Anthony Kolar, Philippe Benabes, and Filipe Vinci dos Santos presented at IEEE International NEWCAS Conference, in June 2017 at Strasbourg, France.

"This paper presents a 14-bit Incremental Sigma Delta (IΣ∆) analog-to-digital converter (ADC) suitable for a column wise integration in a CMOS image sensor. A two-step conversion is performed to improve the conversion speed. As the same Σ∆ modulator is used for both steps, the overall complexity is reduced. Furthermore, the use of inverter-based amplifiers instead of operational transconductance amplifier (OTA) facilitates the integration within the column pitch and decreases power consumption. The proposed ADC is designed in 0.18 µm CMOS technology. The simulation shows that for a 1.8 V voltage supply, a 20 MHz clock frequency and an oversampling ratio (OSR) of 70, the power consumption is 460 µW, achieving an SNR of 83.7 dB."

Sunday, December 10, 2017

Imec Quantum Dot Sensor

MDPI Special Issue on the 2017 International Image Sensor Workshop (IISW) publishes Imec, KU Leuven, and Ghent University paper "Thin-Film Quantum Dot Photodiode for Monolithic Infrared Image Sensors" by Pawel E. Malinowski, Epimitheas Georgitzikis, Jorick Maes, Ioanna Vamvaka, Fortunato Frazzica, Jan Van Olmen, Piet De Moor, Paul Heremans, Zeger Hens, and David Cheyns. The paper describes a somewhat similar to Invisage IR image sensor:

"This work describes a CMOS-compatible pixel stack based on lead sulfide quantum dots (PbS QD) with tunable absorption peak. Photodiode with a 150-nm thick absorber in an inverted architecture shows dark current of 10−6 A/cm2 at −2 V reverse bias and EQE above 20% at 1440 nm wavelength. Optical modeling for top illumination architecture can improve the contact transparency to 70%. Additional cooling (193 K) can improve the sensitivity to 60 dB. This stack can be integrated on a CMOS ROIC, enabling order-of-magnitude cost reduction for infrared sensors."

Saturday, December 09, 2017

Canon Global Shutter Sensor Paper

MDPI Special Issue on the 2017 International Image Sensor Workshop (IISW) publishes Canon paper "Development of Gentle Slope Light Guide Structure in a 3.4 μm Pixel Pitch Global Shutter CMOS Image Sensor with Multiple Accumulation Shutter Technology" by Hiroshi Sekine, Masahiro Kobayashi, Yusuke Onuki, Kazunari Kawabata, Toshiki Tsuboi, Yasushi Matsuno, Hidekazu Takahashi, Shunsuke Inoue, and Takeshi Ichikawa.

"CISs with GS function have generally been inferior to the rolling shutter (RS) CIS in performance, because they have more components. This problem is remarkable in small pixel pitch. The newly developed 3.4 µm pitch GS CIS solves this problem by using multiple accumulation shutter technology and the gentle slope light guide structure. As a result, the developed GS pixel achieves 1.8 e− temporal noise and 16,200 e− full well capacity with charge domain memory in 120 fps operation. The sensitivity and parasitic light sensitivity are 28,000 e−/lx·s and −89 dB, respectively. Moreover, the incident light angle dependence of sensitivity and parasitic light sensitivity are improved by the gentle slope light guide structure."

Friday, December 08, 2017

Huawei is Reported Preparing Triple Rear Camera Smartphone

XDA Developers quotes Venturebeat reporter Evan Blass twitted about the oncoming Huawei smartphone featuring triple rear camera smartphone with 40MP resolution and 5x zoom:

Yole: Camera is Among Major Heat Sources in Smartphones

Yole Developpement report "Smartphones: a significant challenge for thermal management companies" points to camera and LED flash on one of the complex thermal management problems in smartphones:

Thursday, December 07, 2017

Recent ON Semi CCD Advances

MDPI Special Issue on the 2017 International Image Sensor Workshop (IISW) publishes ON Semi paper "Recent Enhancements to Interline and Electron Multiplying CCD Image Sensors" by Eric G. Stevens, , Jeffrey A. Clayhold, Hung Doan, Robert P. Fabinski, Jaroslav Hynecek, Stephen L. Kosman, and Christopher Parks.

"This paper describes recent process modifications made to enhance the performance of interline and electron-multiplying charge-coupled-device (EMCCD) image sensors. By use of MeV ion implantation, quantum efficiency in the NIR region of the spectrum was increased by 2×, and image smear was reduced by 6 dB. By reducing the depth of the shallow photodiode (PD) implants, the photodiode-to-vertical-charge-coupled-device (VCCD) transfer gate voltage required for no-lag operation was reduced by 3 V, and the electronic shutter voltage was reduced by 9 V. The thinner, surface pinning layer also resulted in a reduction of smear by 4 dB in the blue portion of the visible spectrum. For EMCCDs, gain aging was eliminated by providing an oxide-only dielectric under its multiplication phase, while retaining the oxide-nitride-oxide (ONO) gate dielectrics elsewhere in the device."

Queen Elizabeth Prize for Engineering Handed to Image Sensor Inventors

Queen Elizabeth Prize for Engineering has been presented to Eric Fossum, Nobukazu Teranishi and Michael Tompsett. Together with George Smith, who is unable to attend the ceremony, this year’s winners are honored for their contribution to creating digital imaging sensors:

From left to right: Prince Charles, Fossum, Tompsett, Teranishi

Qualcomm Snapdragon 845 Imaging Features

PRNewswire: The new Snapdragon 845 Platform is designed to capture cinema-grade videos and for AR applications:

Spectra 280 ISP:

  • Ultra HD premium capture
  • Qualcomm Spectra Module Program, featuring Active Depth Sensing
  • MCTF video capture
  • Multi-frame noise reduction
  • High performance capture up to 16MP @60FPS
  • Slow motion video capture (720p @480 fps)
  • ImMotion computational photography
  • Dual 14-bit ISPs
  • Hybrid Autofocus
  • Hardware Accelerated Face Detection
  • HDR Video Recording
Adreno 630 Visual Processing Subsystem:

  • 30% improved graphics/video rendering and power reduction compared to previous generation
  • Room-scale 6 DoF with SLAM
  • Adreno foveation, featuring tile rendering, eye tracking, multiView rendering, fine grain preemption
  • Improved 6DoF with hand-tracking and controller support

Hexagon 685 DSP:
  • 3rd Generation Hexagon Vector DSP (HVX) for AI and imaging

Wednesday, December 06, 2017

Leti SPAD Presentation

Leti publishes a presentation on SPAD image sensors it develops together with ST: "Avalanche Diodes for 3D Imaging at Large Distances" by Norbert Moussy. A few slides from the presentation: