Are you using the same voltage supplied to supply Analog supplies and digital supplies ?
You should keep them seperate if at all possible.
If you must use one supply to provide 5V for digital and 5V for analog say then use a ferrite bead to provide to make a nice clean supply for the Analog circuitry.
The ferrite will have a very low DC impedance and a very High AC impedance, so it will allow the DC current to pass bit more of less block any high frequency noise coupling from the digital into the analog section.
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Example of splitting out a 5V supply(from a LDO) to a Digital supply and a clean analog supply...
To be honest forget his labels... You should take the digital supply from +VA and the analog supply from after the ferrite. +VD
http://sound.westhost.com/p85-f1.gif
You should keep them seperate if at all possible.
If you must use one supply to provide 5V for digital and 5V for analog say then use a ferrite bead to provide to make a nice clean supply for the Analog circuitry.
The ferrite will have a very low DC impedance and a very High AC impedance, so it will allow the DC current to pass bit more of less block any high frequency noise coupling from the digital into the analog section.
- - - Updated - - -
Example of splitting out a 5V supply(from a LDO) to a Digital supply and a clean analog supply...
To be honest forget his labels... You should take the digital supply from +VA and the analog supply from after the ferrite. +VD
http://sound.westhost.com/p85-f1.gif
D
Deleted member 432
Lol that stuff sounds so boring i suggest fucking with MILF teachers and getting excellent grades like in porn movies. :welsh:
i'll stick with Heiki idea 
but after i'll graduate.
All caps and supplies where checked - found no decup on digital VDD supply. It was noisy as hell - fixed that issue. Lowered sampling CLK to 8MHz. Now it's ALMOST clean, and less problematic. But still noisy.
Still have crapy codes, but in my environment constraints it's fine, i'm not struggling to full HD lol.
Going to raise my VREF and make signal span 0-4V. Also we decided to connect a battery straight to the digital VDD or may be we will use voltage regulator as you suggested, to make clean and separate supplies.
but after i'll graduate. All caps and supplies where checked - found no decup on digital VDD supply. It was noisy as hell - fixed that issue. Lowered sampling CLK to 8MHz. Now it's ALMOST clean, and less problematic. But still noisy.
Still have crapy codes, but in my environment constraints it's fine, i'm not struggling to full HD lol
. Going to raise my VREF and make signal span 0-4V. Also we decided to connect a battery straight to the digital VDD
or may be we will use voltage regulator as you suggested, to make clean and separate supplies.
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Sounds like you have a plan Art.
Increasing the input span to 0-4v will help to increase your noise immunity but if you input signal from the CCD is only 0-2V output than you have lost half of the range of your ADC
You could try using a amp circuit of Gain = 2 but use some filtering* otherwise you'll just be amplyfing noise as well as signal
* (check out 2nd order butterwoth or Sallen and Key filters)
Increasing the input span to 0-4v will help to increase your noise immunity but if you input signal from the CCD is only 0-2V output than you have lost half of the range of your ADC
You could try using a amp circuit of Gain = 2 but use some filtering* otherwise you'll just be amplyfing noise as well as signal
* (check out 2nd order butterwoth or Sallen and Key filters)
That's exactly the plan, increase of input span will increase noise immunity. We also found that S&H capacitors where too small, they didn't hold proper voltage level.
After repairing the S&H we noticed, that my CCD signal is a bit higher than 2V most of the time, but lower than 4v. I mean the signal at the end of analog chain.
*I know i need some noise reduction, but I don't have additional pads to install my op-amps and don't have much time to wait for post packages.
After repairing the S&H we noticed, that my CCD signal is a bit higher than 2V most of the time, but lower than 4v. I mean the signal at the end of analog chain.
*I know i need some noise reduction, but I don't have additional pads to install my op-amps
and don't have much time to wait for post packages.
