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Testing an ADC is not a simple task.
It depends on ADC technology, it's specifications, and also it's interface.
Testing a delta sigma ADC will be different as testing a flash ADC.
While one is optimised for speed, the other is optimised for good DNL (and other distortions).
The one has almost immediate outpuf, the other has delayed output.
For testing the aperture jitter of the sample and hold circuit of an ADC you most probably won't use the output of a DAC.
It depends on what parameter to test.
To test on DNL or "missing codes" maybe a triangle waveform with DC offset is more simple and more suited than a DAC.
I've assumed that it's a "simple" way as the "first basic check" that ADC conversion process is "at least working true" without any error concern.
Of course it's not necessary and I would be appreciate if you have a more general guide about testing concept for important tasks separately, even referring to some references, for designed ADCs especially for Pipeline ADCs, of note in my case a 12-bit pipeline one using 90nm CMOS tech.
Normally the digital code from an A/D is analyzed by a computer or microprocessor to determine if the code is correct as compared to the A/D input voltage.
Or you could convert the code to BCD and use that to drive a digital display to determine the output word.
But if you want to use a D/A converter it should have at least 14-bit accuracy (use only the 12 upper bits for your test and connect the 2 LSBs to ground). There are many IC's available with that accuracy or better.
Don't try to build your own as you will never achieve 12-bit accuracy using discrete parts.
As what @crutschow refereed it's available to rebuild waveform using output codes of ADC by Computer too (MATLAB) and it is important to take a FFT test for me, of note, I've simulated my ADC by HSPICE, so:
If I want to change my mind, and rebuild it inside MATLAB and take FFT of it, how can I export digital codes from HSPICE to there?
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