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What's Vicm of AD9371 LVDS inputs?

Question asked by jlally on Jan 15, 2018
Latest reply on Jan 17, 2018 by sripad

What is the common mode voltage (Vcm) range of the SYSREF & SYNCIN inputs on the AD9371?  Pg 8 of the datasheet specifies the SYSREF & SYNCIN Input voltage Min=825mV & Max=1675mV.  Using Differential Threshold voltages of +/-100mV results in Vcm-min=0.875V & Vcm-max=1.625V.  This does not seem to comply with the LVDS TIA-644 Receiver Spec of Vcm-min =0.05V, that accounts for ground shift between LVDS transmitter & receiver.  The JESD204B clock source we're considering puts out Sub-LVDS, which could result in a voltage as low as 545mV on the AD9371 LVDS inputs, well below the 825mV specified in the AD9371 data sheet.   Therefore, we need to know if in fact, the AD9371 really does have such a high LVDS input common mode voltage requirement or if perhaps, I'm somehow mistaken.

Thanks, -John

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