redundant area impact Between 1.5bit and 2.5 bit dac

[yefj]

Hello, In the attached article shown bellow we have 2.5 bit ADC we have the 0.5Vref area between -7/8 and 7/8 Vref.
we cannot expand more the 0.5Vref area because we make jumps every 2/8 ,so 7/8 is the maximal availbale.

But In 1.5 ADC its between -1/4 and 1/4 akthough we can make it -3/4 -1/4 1/4 3/4.
What is the effect f the redundant area for 2.5bit.
why making it wider makes itmore accurate.
Il be glad to have some numerical example.

If we

 

[sutapanaki]

What do you mean by redundant area?

 

[yefj]

Hello Sutapanaki, redundant area is the region in 2.5bit where the function stops at +7/8Vref and -7/8Vref.
and in 1.5bit its the area between -1/4vref and 1/4Vref.I cant see how the width of this area matters.
If you could please give a practical example.
Thanks