Comparator accuracy in pipelined ADC

[pbs681]

Hi all,
Could anybody explain to me why by amplify the signal from first stage, we can relaxed the accuracy of the 2nd stage comparator. Another one is, why the first stage comparator is more sensitive to accuracy and the sensitivity get decrease over the stages.
thanks

 

[sunking]

the error of first stage will be double for each flowing stage. So the first is important.

 

[pbs681]

But why we use amplifier?

 

[swicap]

But why we use amplifier?

because we need to hold or amplify the signal.

 

[pbs681]

Thanks all.... but what confusing me is after we substract o/p DAC with input signal, why do we need to amplify the residue signal

 

[Btrend]

that's the spirit of pipeline ADC.
if the residue is not amplified after the subtraction, ur next stage need the same accuracy as ur previous stage.

 

[qutang]

comparator is more important in ad.

 

[yibinhsieh]

pbs681 wrote

Thanks all.... but what confusing me is after we substract o/p DAC with input signal, why do we need to amplify the residue signal

If you do that, the reference voltage can be the same in every satge.

Yibin.