I have upgraded my Quad with the new firmware and FPGA. Now the calibration seems to work much better than before so I made a second time the measure I made before to see if the offset between the two halves of the ADC is still a problem when hiding a channel.http://www.seeedstudio.com/forum/viewtopic.php?p=6828#p6828
There is a bug with new firmware.
When hiding one channel, then display is stretched in the horizontal direction (2 time more samples)
I have made the following acquisitions with a 150KHz sine