which is more linear a 1bit quantizer or multibit quantizer?

[nijMcnij]

distortion

Hi all,

can someone explain to me which is more linear a 1 bit quantizer or a multibit quantizer and why.....how does DEM help in this.

many thanks

 

[safwatonline]

distortion

1 bit quantizer is linear in terms that the output is always two levels (i.e. u can model Vo/Vi by a straight line) but since the gain is input dependent u can say that it is not linear.
while in case of multi-bit quantizer the transfer c/c's can deviate from a straight line which means non-linearity (due to mismatch) but u gain good control on the gain with respect to the input.
so it depends on ur definition of linearity.
DEM is used to convert mismatch error into white error (on the whole fs band ) so u get a reduced mismatch noise in ur band (called mismatch shaping)

 

[naalald]

Re: distortion

Hi
A system is linear if the input and output relation is like this:
y = ax + b
That is a straight line.
A 1-bit quantizer is said to be inherently linear. Since it has just two quantization levels and can be depicted by a straight line between the two levels. The mismatch of the circuit elements may deviate the line from its ideal position but anyway it is still a straight line.
But in the case of the quantizers with two or more bits the mismatch between the elements deviate the lines (which connects each two successive quantization levels) differently and you will not have a straight line any more and these quantizers are not linear. Dynamic Element matching or Digital Correction techniques are needed to improve the circuit linearity.