Thursday, February 18, 2021

ISSCC 2021: Sony 50.1MP Full-Frame Sensor with Sigma-Delta ADC and kTC Noise Reduction

Sony presents its full-frame 50.1MP sensor, apparently used in its new Alpha 1 high-end mirrorless camera:

"A High-Speed Back-Illuminated Stacked CMOS Image Sensor with Column-Parallel kT/C-Cancelling S&H and Delta-Sigma ADC"
by Chihiro Okada, Koushi Uemura, Luong Hung, Kouji Matsuura, Takashi Moue, Daisuke Yamazaki, Kazutoshi Kodama, Masafumi Okano, Takafumi Morikawa, Kazuyoshi Yamashita, Osamu Oka, Itai Shvartz, Golan Zeituni,  Ariel Benshem, Noam Eshel, Yoshiaki Inada.

"Sony presents a 50.1Mpixel, 4.16μm-pitch, back-illuminated stacked CIS with a pipelined column-parallel kT/C noise-cancelling sample-and-hold circuit and a 14b delta-sigma ADC achieving 1.18e-rms random noise at 250fps. The design splits the pixel signal line to lower the wiring load and increase the operation speed."

17 comments:

  1. Hi Vladimir, seems the alpha 1 uses DRAM as well. Is this then a triple stacked device? Impressive is also the stiching in the bottom layer 40nm technology.

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    1. Are you sure about DRAM? I can't find anything about DRAM stacking in Alpha 1 sensor.

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    2. On their product page linked above they say 30fps continous shooting. About 50.1MPix at 10bit result in 1503MPix/s or 1880MB/s. (which is not that fast compared to some industrial sensors, take the e2v Emerald 67M as example for a fast large industrial sensor, this runs 67.1MP 10bit at 65fps or 4360MPix/s or 4550MB/s). 8 lane SLVS-EC output at 4.6Gb/s can handle this easily, I dont see need for locally embedded DRAM in this sensor.

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    3. See e.g. here for a reference to "integral memory" on the alpha 1 sensor: https://presscentre.sony.eu/pressreleases/groundbreaking-alpha-1-camera-marks-a-new-era-in-professional-imaging-3067725

      How else do you get such a fast scan rate with a large resolution?

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    4. They mentioned a full frame buffer in the isscc QA.

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    5. alpha 1 sensor is capable of much more than that. See the 250fps@14bits mentioned?

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    6. you are right, i just browsed the product page first and saw the 30fps. also on the product page they write of "Full-frame stacked 50.1-MP Exmor RS™ CMOS sensor with integral memory", so it seems this could be another 3 layer stack, right? 240fps at 50MP is a bit too fast for the SLVS-EC, 12GPix/s, this is indeed impressive for DSLR. I wonder why they dont advertise this more? Maybe it is not yet available in the camera release even though the sensor supports it?
      But there are sensors on the market that even handle such datarates without onchip buffer, right? One example was the Gpixel Gsprint 4521 recently posted: http://image-sensors-world.blogspot.com/2020/10/gpixel-announces-aps-c-global-shutter.html, 21MP, 1000fps...

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    7. Actually it is advertised a lot. It is called "silent shutter". At 250fps readout it is equivalent to mechanical shutter. Not clear if storage is done on sram or on a 3rd layer DRAM.

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    8. Ah... another wrong paradigm in my head ;-) somehow a 'semi global shutter' fast rolling shutter readout into buffer memory to minimize rs artifacts? This has more value for dslr user than 240fps bursts

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    9. Why you keep calling it dslr?

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    10. A1 outputs 50.1MP 30fps at 14bit.

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  2. It also reminded me to the alpha 1 :-)

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  3. Stacked Sigma Delta in a commercial sensor, did not expect it so soon. Anyone know how many ADC per column?

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    1. 4 columns/ADC. North and south side have their own ADC's (pixel bus split in middle).

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    2. Just wondering, what would be the biggest challenge to implement sigma delta in a commercial sensor (not to mention stacked)?

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    3. Power consumption and die space

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  4. nice interview about the camera and sensor with Masaaki Oshima, Deputy Senior Manager of Sony's Camera division:
    https://www.dpreview.com/interviews/9195902169/interview-sony-s-masaaki-oshima-the-alpha-1-is-the-first-step-towards-the-next-decade

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