noise level has increased after offset correction circuit modification
To get rid of the "dip" in frequency response, the offset correction circuit has been modified slightly. As a result, the gain of the offset buffer is higher for some frequencies, so the noise coming from the voltage reference source are amplified more. As a result, the ENOB factor for the most sensitive range of FmcAdc card felt down to 10.2 bits. For all other ranges is still better than 11 bits. The proper solution would be to add follower behind the ref. source and to cut off the bandwidth of the source by using low pass filter. The changes mentioned above could be applied for the next version of the board - the work flow for the version 2 is already finished.