Thursday, July 05, 2012

Temporal Noise in the Dark

Albert Theuwissen continues his article on temporal noise in the dark measurements. The thirs part covers row temporal noise over the exposure range.

13 comments:

  1. Albert, what are the sources of raw RMS noise please?? Thanks!

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  2. Albert TheuwissenJuly 6, 2012 at 9:16 AM

    Do you mean row temporal noise ?

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  3. There could me many sources for row noise, for instance:

    - supply noise, if PSRR is not high enough
    - bias circuits noise. They are common for the whole readout
    - column-level ADC reference voltage noise, or ramp noise in case of ramp ADC
    - coupling from digital part or digital I/O through the common substrate
    - many more reasons, sometimes very implementation-specific

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  4. thanks! do you think that 1/f noise is ultimate noise source?

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  5. For the row noise? Not necessarily. See the list of the noise sources in my comment above.

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  6. Albert TheuwissenJuly 8, 2012 at 10:46 AM

    To Vladimir : thanks for answering the question.
    To Anonymous : take also into account that the transfer gate, reset and row select lines run horizontally. While the column bus is running vertically. So cross talk of all pulses can introduce extra noise on the analog channel as well.

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  7. these crosstalks should be able to be avoided by a careful analog design and operation range setting. Basically 4T pixel works in a pure charge mode, so if all the devices can be kept in linear mode, the charge converation should be able to suppress these crosstalks.

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    Replies
    1. What about the rest of the signal path? This is where the rubber meets the road, as they say. Think again about what VK and AT said about noise sources and capacitive coupling.

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    2. How many chips have you designed really please?

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  8. Doesn't row signal delay or resistive drop in large arrays introduce row noise?

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    Replies
    1. Those tend to be fixed pattern noise issues, but they can also contribute to temporal noise.

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