SAR ADC formula comparison

[yefj]

Hello ,the general form of SAR ADC is as shown bellow in the formula but when i try to develop the 3 bit private expression for 3 bit as shown bellow:
i try
101 is 4C+C
But i cant see how \[ \frac{(N-X)}{N}=5/8 \]
N=2^3 X=3
X is Bits that set in a givern corevention
why in our private case X=3?
Thanks

 

[sutapanaki]

 

[yefj]

Hello,we have a genral formula for the SAR ,
N=2^3-8
Why X=3 ? (bits that set in a given convertion)

 

[sutapanaki]

Maybe it is good to give a link to the thing you are reading so people can get the whole picture.

 

[yefj]

Hello,The genaral formula on slide 18 of the attached leacture
i am tryong to understand why th provate case in slide 14 means X=3?
Thanks

 

[yefj]

Hello,In the formula shown bellow why the charge between V+ and GND is minus to the charge of Vref and V+ ?
Thanks.