Sigma delta quantization error tape-out circuit

[meghna]

Dear All,
Can anyone tell me some good reference of the circuit used for tapping out the quantization error of the internal quantizer (flash ADC). In my architecture, I have to take the quantization error of the first stage and convert it into digital in the second stage, so that can be substarcted from the first stage output in the digital domain.

Thanks and Regards
Meghna