Image sensor noise definition and measurement

[rficdesigner]

Hello everyone,

Do you have any idea in noise definition and measurement for CMOS image sensor?
As far as I know, to find the RMS noise of the image sensor, we will get the N sample values of output signal of a pixel at, then calculate the standard derivation of these samples => RMS noise.

Am I right? Do you have any idea please share?

 

[keith1200rs]

That is correct, as far as I know. I also think the standard deviation = the RMS noise value assuming Gaussian noise.

Keith.

 

[rficdesigner]

Do you have any suggestion on noise measurement of image sensor readout IC?
which instrument suitable?
As I often do, I get the N samples and then calculate the standard derivation manually.
I checked a commercial IC noise performance. The chip operated properly. However, its the RMS noise is much higher than the value in datasheet.
I cannot figure out what is the reason?

Any idea?

 

[keith1200rs]

It is not a device I have ever tried to measure the noise of. However, I have made quite a few noise measurements of analogue circuitry and it is difficult to achieve datasheet figures because it is very dependant on the layout and noise from power supplies etc. It might be worthwhile doing a fourier transform of the noise to see if there are any specific frequencies present, rather than it being random. That could be caused by coupling of clocks into the analogue circuitry.

Keith.

 

[rficdesigner]

Thanks Keith.

It seem to be a good idea.