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Message ID: 298     Entry time: Mon Oct 21 14:43:21 2013
Author: Stephane Debieux 
Subject: DRS4 analog outputs - interfacing DRS4 to AD9222 ADC 

Hi,

I wish to interface the DRS4 with the 8-channel ADC AD9222 (or AD9637).

I'm reading from the DRS4 datasheet that "the analog output of the DRS4 chip has been designed to match directly the input of the AD9222". OUT+ output of DRS4 is in the range from 0.8V to 1.8V and OUT- output is shifted by the voltage applied to the O-OFS pin.

The span of the AD9222 ADC core is defined by REFT and REFB which are resp. 1.4V and 0.4V in a typical case (AVDD=1.8V, VREF=1V). My understanding is that the ADC analog inputs must be within the voltage range defined by REFT and REFB and so I don't quite see how this matches the DRS4 outputs.

Can we use the full-scale range indeed? Do we have to use AC-coupling with mid-supply bias? What is the point I missed?

Thank you for your help.

 

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