reference voltage and capacitor values in ADC

[amr hema]

hi all,
how can i know the value of reference voltage of ADC and what's its effect ?
also how to determine the value of unit capacitor in DAC in SAR ADC ?

 

[Tahmid]

hi all,
how can i know the value of reference voltage of ADC and what's its effect ?

Your ADC reading depends on the reference voltage and the actual input voltage.

Read here under the section "Voltage Reference and ADC result" : https://www.edaboard.com/blog/1569/

Hope this helps.
Tahmid.

 

[amr hema]

ok but my graduation project is sar adc , and i want to know how to determine its value and value of full scale input

 

[Junus2012]

Hello

the reference voltage is the the voltage that the ADC will convert the analog signal with respect it. suppose for example, in your application you have an input analog signal with maximum peak-to-peak is 1 V. then you should make the reference voltage of the ADC equal to 1 V. Assume that you are using 8 bits ADC, when the input of 1 V is applied the converter will make this comparision: 1V/1V*8=8 = FF. if an input of 0,5 is applied the result is (0.5/1)*8=4=0F.

in simple way, the reference voltage of the ADC should be equal to the maximum expected input analog signal

 

[amr hema]

thanks alot

 

[Junus2012]

you are welcome