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AD9689 Vcm export voltage

Question asked by Jonas.grue on Jul 3, 2018
Latest reply on Jul 10, 2018 by modimo



I have designed AD9689 board with dc-coupled amplifier in front of ADC.

For right common mode of amplifier output and ADC input, ADC Vref pin is connected to amplifier vcm input pin.

Vcm export voltage measured at VREF is about +1.8V. Datasheet states no value of Vcm export voltage but 1.4V typical for common mode analog input voltage only. I think, 1.8V Vcm doesn't really match to typical 1.4V Vcm Input, am I right? Is it a problem or can I ignore it?


Best regards