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What is the input bias voltage of AD9634 and can it be changed?

Question asked by markusvr on Mar 17, 2017
Latest reply on Mar 19, 2017 by markusvr

Hello,

 

in our use of the AD9634 we've seen that the inputs of the AD9634 draw an input current if they had a common mode voltage of 0.6V instead of the 0.9V given throughout the datasheet and measured at the VCM pin.

The current drawn from the pins seems to be in the range of a switched capacitor of 4pF at 250MHz, the calculated current from 20k differential input resistance is factor 40 below.

 

Is there a hidden register to modify the bias voltage in figure 46 in the datasheet (rev. B) or should the common mode voltage of the input signals be set to 0.6V in order to drive the inputs at least load and the least switching noise?

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