AnsweredAssumed Answered

AD9288 - Common Mode Input Range

Question asked by AlexB on Jun 28, 2011
Latest reply on Jul 5, 2011 by ChrisH

Hello All,

 

I am working with the AD9288 ADC. I have a DC coupled application, and single ended inputs. I am considering doing a single ended only implementation or a single ended to differential conversion.

 

1) On page 14 of the datasheet, it says "The nominal input range is 1.024 V p-p centered at VD × 0.3." If I use a VD (analog supply voltage) of 3.0V, that would correspond to a 900mV common mode bias point (correct?) If the input range is 1.024V, that would tell me that my upper range is 0.9 + 0.512 = 1.412V and my lower range is 0.9 - 0.512 = 0.388V. Are these calculations correct?

 

VD*0.3 center voltage seems a bit odd to me. I am used to single supply systems with the virtual ground being around 1/2 Vsupply. Can the AD9288 be modified to accept a common mode voltage range of (1/2)*3V = 1.5V? Will this significantly degrade performance?

 

2) If I choose to retain a fully single ended signal, should I layout a similar arrangement as the AD9281's datasheet on page 10 figure 22 (0V - 1V input)?

 

Thank you for your suggestions,

Alex

Outcomes