Explaining the DNL defintion

[hanklu]

I see the DNL
The data from **broken link removed**
**broken link removed**

and he say
Differential Nonlinearity (DNL) is a measure of the separation between adjacent levels
measured at each vertical step (% or LSB).
DNL = (Dcx - 1) LSBs
where Dcx is the size of the actual vertical step in LSBs.

but I see the other image is different
It like this
I confused with it's one of horizontal and the other is vertical
which is right?

 

[sunking]

About DNL problem

They are the same.

 

[tatakt]

Re: About DNL problem

Hi,
The important point is the "maximum DNL" which is the same for both vertical and horizontal mesurement.
Good Luck,
Tata

 

[jiangwp]

Re: About DNL problem

I think the second is right.

The INL and DNL is defined with aspect to the analog signal.

 

[nxing]

About DNL problem

Why are they same? Can anybody explain it?

 

[willyboy19]

Re: About DNL problem

DNL should be related to the analog input signal for ADC and analog output signal for DAC. That is why DNL can be a factional number (like 0.7LSB). Therefore, you should use the second plot.

 

[ocarnu]

Re: About DNL problem

First is wrong, the second is right. There is no physical meaning in difference beteen codes, they are gust numbers, without a physical value.

 

[Btrend]

Re: About DNL problem

from Martin's book,
DNL is defined as the variation in analog step sizes away from 1LSB (typically, gain and offset errors have been removed).

 

[tuza2000]

About DNL problem

there are two different defination of DNL;
one is define the max (step size - 1LSB) as the DNL of the circuit
the other is give every setp the defination of DNL as (step size -1LSB )

they are the same in essentially!

 

[ocarnu]

Re: About DNL problem

There are not two definitions, it is only one, the second. The other one is called Maximum DNL. It is true though that people forget sometimes to put maximum in front when they characterize chips (in datasheets).

 

[carlyou]

About DNL problem

the first one is right

 

[rvenigal]

Re: About DNL problem

both ways are ok to quntify DNL. Only diffrence is that in first plot you can quantify only discreet levels. where as in second you can quntify the fractional DNL also. Now choice is yours i prefer second one.