Minimum resolution required for testing an n-bit ADC?

[SherlockBenedict]

Let's say that I have bought a 10-bit ADC (say). I am trying to test that ADC using a measuring instrument which has its own ADC. What should be the minimum resolution of that ADC in that measuring instrument?
(Assume that voltage rail-rail swing is same for both ADCs )
So What is the minimum resolution required for testing an n-bit ADC?

Thanks in advance.

 

[Kripton2035]

well - better than 2^n
so for 10, 2^10 = 1024 .

 

[crutschow]

To be safe, I would use about 10 times the resolution of what you are measuring or 13 or 14 bits for a 10-bit part. If it's not critical then perhaps 12-bit resolution (4 times) would suffice to test 10-bits.

 

[SherlockBenedict]

To be safe, I would use about 10 times the resolution of what you are measuring or 13 or 14 bits for a 10-bit part. If it's not critical then perhaps 12-bit resolution (4 times) would suffice to test 10-bits.

Why not use 11 bit or 10 bit resolution itself for 10 bit ADC having told that both have same rail-rail swing and same levels?

 

[crutschow]

Why not use 11 bit or 10 bit resolution itself for 10 bit ADC having told that both have same rail-rail swing and same levels?

Because you always want the measuring instrument to be more accurate than whatever you are measuring. A 10-bit converter typically has at least ±1 bit of error so your measurement accuracy would be no better than that. 11-bit resolution would give 1/2 bit resolution of the 10-bit signal, which would be marginal but perhaps usable if you don't need to accurately characterize the 10-bit device. Remember resolution and accuracy are not the same thing.