Wednesday, February 21, 2018

Inerview with Nobukazu Teranishi

Nikkei publishes an interview with Nobukazu Teranishi, inventor of the pinned PD who recently was awarded the Queen Elizabeth Prize for Engineering.

"Now... except for Sony, which leads the world in the image sensor sector, Japanese companies have fallen behind, particularly in the semiconductor industry.

Teranishi said that changes are necessary for Japan to continue to compete globally.

He also suggested that engineers and technical experts should be held in higher esteem in Japan.

"Excellent engineers are a significant asset. Companies overseas shouldn't be able to lure them out of Japan just with better salaries. If they are that valuable, their value should to be recognized in Japan as well," he said.

Determining salaries by how long people have been at the company seems like "quite a rigid structure," he said.

He added that engineers get little recognition for the work they do, with individual names rarely mentioned within the company or in the media.

Looking ahead to the future of image sensors, Teranishi feels one peak has been reached, with around 400 million phones produced annually that incorporate his technology. Next, he says, is the era of "images that you don't see."

For facial recognition and gesture input for games, he said, "No one sees the image but the computer is processing information. So there are many cases where a human doesn't see the image.

CIS Wafer Testing Presentation

Taiwan Jetek Technology publishes a presentation on CIS wafer-level testing.

Tuesday, February 20, 2018

IR-Enhancing Surface Structures Compared

IEEE Spectrum: TED publishes UCD and W&WSens Devices invited paper on light-bending microstructures to enhance PD QE and IR sensitivity "A New Paradigm in High-Speed and High-Efficiency Silicon Photodiodes for Communication—Part I: Enhancing Photon–Material Interactions via Low-Dimensional Structures" by Hilal Cansizoglu, Ekaterina Ponizovskaya Devine, Yang Gao, Soroush Ghandiparsi, Toshishige Yamada, Aly F. Elrefaie, Shih-Yuan Wang, and M. Saif Islam.

"[Saif] Islam and his colleagues came up with a silicon structure that makes photodiodes both fast and efficient by being both thin and good at capturing light. The structure is an array of tapered holes in the silicon that have the effect of steering the light into the plane of the silicon. “So basically, we’re bending light 90 degrees,” he says."

The paper compares the proposed approach with other surface structures for IR sensitivity enhancement:

Monday, February 19, 2018

Corephotonics and Sunny Ship Millions of Dual Camera Modules to Oppo, Xiaomi and Others Corephotonics has partnered with Sunny Optical to bring to market a variety of solutions based on the company’s dual camera technologies. Under this agreement, Sunny has already shipped millions of dual cameras powered by Corephotonics IP to various smartphone OEMs, including Xiaomi, OPPO and others.

The new partnership combines Sunny’s automatic manufacturing capacity, quality control and optical development capabilities with Corephotonics’ innovation in optics, camera mechanics and computational imaging. This strategic license agreement covers various dual camera products, including typical wide + tele cameras, as well as various folded dual camera offerings, allowing an increased zoom factor, optical stabilization and a reduced module height.

The partnership allows Sunny to act as a one-stop-shop dual camera vendor, providing customized dual camera designs in combination with well-optimized software features. The collaboration leverages Sunny's manufacturing lead and strong presence in the Chinese dual-camera market.

Sunny Optical has the powerful optical development capability and automatic lean manufacturing capacity. We have experimented with virtually all dual camera innovations introduced in recent years, and have found Corephotonics dual camera technologies to have the greatest contribution in camera performance and user experience. Just as important is the compliance of their dual camera architecture with high volume production and harsh environmental requirements,” said Cerberus Wu, Senior Marketing Director of Sunny Optical.

We are deeply impressed by Sunny's dual camera manufacturing technologies, clearly setting a new benchmark in the thin camera industry," added Eran Briman, VP of Marketing & Business Development at Corephotonics. “The dual camera modules produced under this collaboration present smartphone manufacturers with the means to distinguish their handsets from those of their rivals through greatly improved imaging capabilities, as well as maximum flexibility and customizability."

EETimes Reviews ISSCC 2018

EETimes Junko Yoshida publishes a review of ISSCC 2018 image sensor session, covering Sony motion detecting event-driven sensor:

Microsoft 1MP ToF sensor:

Toshiba 200m-range LiDAR:

and much more...

Saturday, February 17, 2018

Materials of 3rd Workshop on Image Sensor and Systems Published

Image Sensor Society web site published most of the papers from 3rd International Workshop on Image Sensor and Systems (IWISS2016) held at the Tokyo Institute of Technology in November 2016. There are 18 invited papers and 20 posters presented at the Workshop, mostly from Japan and Korea.

Thanks to NT for the pointer!

Friday, February 16, 2018

LIN-LOG Pixel with CDS

MDPI Special Issue on the 2017 International Image Sensor Workshop publishes NIT paper "QLog Solar-Cell Mode Photodiode Logarithmic CMOS Pixel Using Charge Compression and Readout" by Yang Ni.

"In this paper, we present a new logarithmic pixel design currently under development at New Imaging Technologies SA (NIT). This new logarithmic pixel design uses charge domain logarithmic signal compression and charge-transfer-based signal readout. This structure gives a linear response in low light conditions and logarithmic response in high light conditions. The charge transfer readout efficiently suppresses the reset (KTC) noise by using true correlated double sampling (CDS) in low light conditions. In high light conditions, thanks to charge domain logarithmic compression, it has been demonstrated that 3000 electrons should be enough to cover a 120 dB dynamic range with a mobile phone camera-like signal-to-noise ratio (SNR) over the whole dynamic range. This low electron count permits the use of ultra-small floating diffusion capacitance (sub-fF) without charge overflow. The resulting large conversion gain permits a single photon detection capability with a wide dynamic range without a complex sensor/system design. A first prototype sensor with 320 × 240 pixels has been implemented to validate this charge domain logarithmic pixel concept and modeling. The first experimental results validate the logarithmic charge compression theory and the low readout noise due to the charge-transfer-based readout."

"The readout noise was measured at 2.2 LSB, which is 268 µV. Taking into account the source follower gain, the temporal noise on the floating diffusion was estimated at 335 µV. With a floating diffusion node capacitance estimated from design at 4 fF, the noise electron number is 12.3 electrons. The temporal noise in the logarithmic regime was measured at 6 LSB, which represents 34 electrons inside the buried photodiode. From this Johnson noise, the photodiode capacitance can be estimated at 6.2 fF which is quite close to the estimation from the layout."

Thursday, February 15, 2018

DALSA Discusses Facial Recognition

Teledyne DALSA starts publishing a series of articles on facial recognition science. The first part discusses fairly generic issues, such as the resolution that humans use for facial recognition task. It's all dynamic:

"The ganglion cells in the human retina can produce the equivalent of a 600 megapixel image, but the nerve that connects to the retina can only transmit about one megapixel."

"Analysts predict that the global facial recognition market is expected to grow from USD 4.05 Billion in 2017 to USD 7.76 Billion by 2022. Companies are very interested in the possibilities of facial recognition technologies and global security concerns are driving interest in better biometric systems."

ISSCC Review: Sony, TSMC, NHK, Toshiba, Microsoft, TU Delft, FBK

Albert Theuwissen continues his review of ISSCC 2018 presentations. The second part includes Sony 3.9MP, 1.5um pixel pitch event-driven sensor:

"The overall resolution of 3.9 Mpixels is reduced to on 16×5 macro pixels. In this “macro” pixel mode, the power consumption is drastically reduced as well, and the sensor behaves in a sort of sleeping mode. Once the sensor detects any motion in the image (by means of frame differencing), the device wakes up and switches to the full resolution mode."

TSMC presents their 13.5MP 1.1um pixel sensor and NHK unveils 8K 36MP 480fps sensor for slow-mo sports shooting at the oncoming Tokyo Olympics.

The third part of the review starts with Toshiba hybrid LiDAR that is enhanced by a Smart Accumulation Mode that, basically, tracks the subjects in depth domain. As long as it works, the detection range can reach 200m, but it relies on a lot of intelligence inside what is supposed to be just a dumb sensor delivering the "food for thought" to the main CPU or NPU.

Microsoft presented an evolution of its ToF sensor used in Kinect-2 - higher resolution, smaller pixels, BSI, higher QE, better shutter efficiency, etc. AGC has been added to the pixel, and background light suppression has been removed, if we compare this pixel with the previous Microsoft design.

TU Delft and FBK presented SPAD designs. The FBK one is aimed to entangled photon microscopy to increase the resolution by a factor of N, where N is the number of mutually entangled photons.

Albert Theuwissen concludes his review on an optimistic note:

"Take away message : everything goes faster, lower supply voltages, lower power consumption, stacking is becoming the key technology, and apparently, the end of the developments in our field is not yet near ! The future looks bright for the imaging engineers !!!"

Panasonic 8K GS OPF Sensor

Panasonic has developed an 8K (36MP), 60fps, 450ke- saturation sensor with global shutter and with sensitivity modulation function. The new CMOS sensor has an organic photoconductive film (OPF).

"By utilizing this OPF CMOS image sensor's unique structure, we have been able to newly develop and incorporate high-speed noise cancellation technology and high saturation technology in the circuit part. And, by using this OPF CMOS image sensor's unique sensitivity control function to vary the voltage applied to the OPF, we realize global shutter function. The technology that simultaneously achieves these performances is the industry's first."

The new technology has the following advantages:
  • 8K resolution, 60fps framerate, 450Ke- saturation and GS function are realized simultaneously.
  • Switching between high sensitivity mode and high saturation mode is possible using gain switching function.
  • The ND filter function can be realized steplessly by controlling the voltage applied to the OPF.

This Development is based on the following technologies:
  1. "OPF CMOS image sensor design technology", in that, the photoelectric-conversion part and the circuit part can be designed independently.
  2. "In-pixel capacitive coupled noise cancellation technique" which can suppress pixel reset noise at high speed even at high resolution
  3. "In-pixel gain switching technology" that can achieve high saturation characteristics
  4. "Voltage controlled sensitivity modulation technology" that can adjust the sensitivity by changing the voltage applied to the OPF.

Panasonic holds 135 Japanese patents and 83 overseas patents (including pending) related to this technology.