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AD9643 SNR Vs input span

Question asked by nikhil on May 30, 2013
Latest reply on Jun 10, 2013 by J.Harris

Hi,

Is there any relation between the ADC SNR and its input voltage span ? We are using AD9643 on our board with 160MHz sampling range. while looking at the SNR figures we are getting different figures when we change the input voltage span of the ADC. the difference we are getting fron changing from full scale 2.08V to 1.75 is around 5-7dB.  But even if we reduce the voltage range difference after changing to dB then also it should not be that much it should be around 2 dB.

Is there any specific input span which is recommended for best performance ?

Also this change is present in one channel (ADC A) only other channel seems to increase by 1-2dB only while changing the span.

 

Thanks and Regards,

Nikhil

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