which source to use?

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Anonymous
Not applicable

 i want to connect 2.048V source to the negative input of ADC in the top design layout in Creator 2.1.which source shall i use?VDAC,battery or Vref?

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ETRO_SSN583
Level 9
Level 9
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Why the offset to ADC ? Are you using + input to ADC from a bridge

   

element, a little better description of why you need the offset would

   

help forum assist you.

   

 

   

In general, offsetting from a reference would make most sense to

   

preserve absolute accuracy, if thats what you are seeking.

   

 

   

Regards, Dana.

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Anonymous
Not applicable

You can use a VDAC for giving offset of 2.048V or a Vref component followed by PGA of gain 2.

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ETRO_SSN583
Level 9
Level 9
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Keep in mind the onboard reference is accurate to +/- .1% and the

   

PGA gain error is > +/- .15%, its offset error is 10 mV, and its PSRR

   

is 48 db, so factor those into your error analysis.

   

 

   

Regards, Dana.

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Anonymous
Not applicable

Using a battery is something that i would suggest, if you are looking for a higher resolution(higher ENOB).

   

If you are OK with a resolution less than or equal to 16bits, then you can seek the help of references and DACs as the preconditioning circuit always reduces the ENOB.

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ETRO_SSN583
Level 9
Level 9
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A battery is not a panacea for fixing a reference problem, as it has

   

a noise contribution, its noise rises with depletion, and usually one

   

needs a R network to get the reference voltage of interest which also

   

contributes to ENOB reduction.

   

 

   

Conduct a complete signal chain analysis and that will reveal the issues.

   

 

   

Regards, Dana.

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ETRO_SSN583
Level 9
Level 9
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Battery noise reference -

   

 

       

http://www.cerc.utexas.edu/~arjang/Papers/J2.pdf

   

 

   

Regards, Dana.

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Anonymous
Not applicable

Best is to try out all possibilities and select which is suiting your requirements.

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