What are the causes of residue drop in ADC?

[moisiad]

Hi

In the 1bit pipeline ADC i have designed , i have noticed a drop in the residue from stage to stage,resulting in missing codes. I have also read that this is due to capacitor mismatch. However in schematic level, where i am working now, there is no capacitor mismatch.
Is there any other reason which may cause residue drop?

thanks

 

[wsy979]

Residue drop in ADC

dear moisiad

i think u'd better check the gain and settling time of residue-amp

but why not use 1.5 bit per stage

regards

 

[sunking]

Residue drop in ADC

does it be gain error?