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AD9106 - How can we compute the output noise ?

Question asked by Marc38 on Jul 31, 2018
Latest reply on Aug 10, 2018 by mcee

Hello,

I try to estimate the noise of my system, which use an AD9106 as a high frequency voltage source.

The value in the datasheet is -167dBm/sqrt(Hz) I tried to convert it in nV/sqrt(Hz) to get 1nV/sqrt(Hz).

It seems quite low to me yet not impossible. Also the output is a current should I convert the noise in current ? I would expect the noise to depend on the resistance used to convert in voltage.

 

Another question : would it be possible to use the outputs of the DDS directly to drive the inputs of a differential amp ? (please refer to the schematic attached)

In the evaluation board, there are 250ohms resistors used to convert the current in voltage then a differential amplifier. However, it forces to use larger resistors for the input of the OPA to not affect the current to voltage resistors, that increases noise.

 

Thank you,

Marc

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