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Voltage offset differences under different sampling rates?! - AD9265

Question asked by HankFrance on Jun 17, 2014
Latest reply on Jul 10, 2014 by HankFrance

Dear all:

     I met a problem totally different from my old experiences with under 10MHz ADC. I found that the output data of AD9265 will be different in different sampling rate, even the same input source (function generator with high impedance output).

     For example, giving a 0.4V input, I got 0.4V in 10Msps, but 0.41 in 100Msps. Is this the feature of AD9265 or ?!

And I found the offset will increase in higher input voltage. ex 0.8V input, 0.8V in 10Msps. but 0.82V in 100MSps.

 

At first, I doubt the voltage reference may be affected when ADC operates faster in 100MSps. I applies a high-speed OPAMP to drive the voltage reference input. Furthermore, I applied the expensive low-ESR capacitor to stabilize the reference, but all of these are useless.

 

Had anyone experienced this?! Please give me some advice how to deal with this problem. Thank you.

 

Best Regards,

Hank

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