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AD9978 Input

Question asked by Yvan on Jun 13, 2016
Latest reply on Jun 27, 2016 by Yvan

Hi,

I am working on the design of a driver for the AD9978.

 

I am new to this kind of application and I was wondering If I could get some advice/suggestion to properly design this circuit.

 

  • In particular, I’d like to evaluate the “Equivalent Input Noise” of AD9978.

From the datasheet I could get that the Total Output Noise of the system is 2 LSBrms, but how to translate this data to the input?

I want to compare the noise at the output of my driver circuit with the AD9978 input noise.

 

  • On an other hand, I was wondering If I could implement a driver based on a Transformer (the center tap connected to a DAC output to adjust the DC level at the input of the AD9978.)

The CCD signal at the input of the driver is 10MHz – 0.25Vpp – 12Vdc. The idea would be to substract the DC component and then to add a “noise free” gain using a 1:2 or 1:4 ratio Transformer.

 

  • About input configurations: The differential input configuration proposed in the datasheet is DC –coupled. Is there any problem in building an AC-coupled differential configuration and then using the DC-restore option on both INP and INN inputs?

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