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Design >> Mixed-Signal Design >> resolution of ADC?
https://designers-guide.org/forum/YaBB.pl?num=1148829008

Message started by chungmnig on May 28^th, 2006, 8:10am

Title: resolution of ADC?
Post by chungmnig on May 28^th, 2006, 8:10am

Hi~~
If said a ADC has 12bits,then the reference voltage = 2V
then the smallest can measured voltage = 2/(2^12) = 4.88mV (it means LSB) ,
and if reference voltage = 1 V --> 1/(2^12) = 2.44mV ,
so the reference voltage =1 can measure smaller voltage if ADC's bit =12

Is this statement is right?
thanks~~~

Title: Re: resolution of ADC?
Post by Marc Murphy on May 28^th, 2006, 9:21am

Yes. If you have a 4-bit converter and full-scale voltage is 10 V, the value of the LSB is 10/(2^4)=0.625 V. The highest value is 15, which translates to 9.375 V, or Fullscale - 1 LSB.

I hope this eases your mind! :)

Cheers,
Marc

Title: Re: resolution of ADC?
Post by Paul on May 28^th, 2006, 3:52pm

Hi,

yes, your statement is correct if your ADC is quantization noise limited. In many cases, the resolution may however be determined by the thermal noise level, in which case the lowest value to be measured is reference-independent. In that case, using the larger reference voltage maximizes your dynamic range (if we neglect distortion).

Paul