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Tuesday, October 12, 2010

RTS Noise in Pixels Explored

The new part in Albert Theuwissen's PTC series covers RTS noise in pixels and how it affects PTC. The conclusion is simple: "the presence of the RTS pixels has no major influence on the PTC curve. All parameters extracted are very similar to a simulation without RTS pixels. To detect the characteristics of the RTS pixels, other tools than the PTC need to be applied."

6 comments:

  1. what could be the reason of RTS noise in a pixel ?
    Is there a relation/correlation with dark current value ?

    thanks !

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  2. In an APS, RTS noise originates due to the "discrete" trapping and detrapping of carriers in the channel of the source follower. 1/f (dont know if RTS-> perhaps very small diodes?) can also be produced due to dark current carrier fluctuation in the diode during integration. It should depend on frequency rather than dark current value itself

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  3. Thanks !

    I understand the original of RTS in source follower. Maybe there are also such charge trapping and release processes inside a PN junction ? But if this is the cause, there should be agregation effect of the trapped charges ?

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  4. Well, it really depends on the number of slow traps present in pn junction, the capture and release/emission time of the traps, etc. However, I am not sure whether a trapped carrier will be released in the next frame--> will not the reset process empty the charge? Maybe an expert could answer to this point.

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  5. The origin of RTS as explained in the second comment is the generally accepted model. However, RTS pixels can give rise to a change in voltage at the source-follower node of 50 mV or even more. As far as I can recall, there is no explanation for this effect : how can the capture or release of a single electron give rise to such a large voltage swing ? I discussed this with several experts in the field of semiconductor technology/physics, but I did not got an answer yet ... Apparently there is still work to do to get everything explained, that is the positive side of RTS.

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  6. Thanks Albert,

    I read some where that the release/emission processus could be a locally collective behaviour, similar in a laser device. This means that several traped charges can be released collectively after a single charge is released. Can you comment this please ?

    Yang Ni

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