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High Speed ADC Consideration.

Question asked by smutha on Jun 24, 2013
Latest reply on Jun 28, 2013 by David.Buchanan

Hello All,

            A few queries about selecting the right ADC for our application, the requirements being the following:

1) Single channel

2) Measured results for Fin > 400MHz

3) Preferably serial LVDS output


Also a query regarding sub-sampling and over sampling.

1) Over sampling is a good thing because it spreads the quantization noise over a wider bandwidth, thereby decreasing the total noise in a smaller bandwidth.

2) Sub-sampling is affected by noise folding but can achieve the datasheet noise floor by using good band pass filters(BPF). My question is, how does one calculate the rejection requirement of the BPF (30dB, 40dB ... )?

In a subsampling system how does one evaluate the cumulative effect due to the increase in the quantization noise and also because of noise folding. Together they will give rise to a higher (much higher?) noise floor; is this avoidable?