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ADC voltage reference

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guow06

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I've seen ADC with on-chip voltage reference. Does an ADC usually have an on-chip reference?
The problem is that I am designing an ADC and I need two voltage references (Ref and Ref/16). For writing a paper, I can leave it alone. But for real design, should I worry about the Ref/16 reference? like if ref = 1v, there is no way I can get a accurate 62.5mV (error within 1%) in a real application. If I do need a Ref/16 and Ref, it is better I design it on-chip by myself, right?
 

If the ADC is more than 10 bits I will use an external reference. If the ADC is more than 16 bits I will use an temperature controlled external reference
 

Yes
Depends what ADC using. On some you can simple switch beetwen internal/external reference.
You can using voltage divider to get lower voltage reference! But allways be cerfull to be stabilized before adc conversion!
 

Many ADCs are now built on technologies that are not that good for precision
references - lacking control of the diode or BJT attributes, lacking stable and
well controlled resistors and so on.

Old-school outfits like ADI and LTC own and control specialized processes that
enable reference art unavailable to mere mortals. And your low-cost CMOS flow
that people like to use, doesn't give much of a damn about diodes, which are
supposed to be tied off and inactive more or less. Yes, you could use them.
Yes, you could model them better and maybe do a 10-bit job. Until somebody
tweaks a knob and your critical yet "non-valued" core device shifts its TC or
Vf by more than 0.1%, and you get to participate in an unscheduled redesign.
 

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