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."


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

    thanks !

  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

  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 ?

  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.

  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.

  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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