Sigma Delta Loop filter (CIFB) question!!

[ljy4468]

delta loop

Hi
I've a question about CIFB loop filter.
In a book "understanding delta sigma data converters - richard schreier"
In page 115, there is CIFB structure.
and there aren't feedback between first and second intgrators (coefficient : g)

But In the delta-sigma toolbox(delsig)
there are feedback coefficient g .

and for determine coefficient, there is always g!

could you explain that please???



https://obrazki.elektroda.pl/5_1186043747.jpg


attached is from delta sigma toobox.pdf from R.schreier

 

[cec]

cifb sigma delta

"understanding ..." Page 118-119 better SQNR performance may achieved ?

 

[panditabupesh]

delta filter

g moves the NTF zero from dc to somewhere in-band (is a real resonator). In synthesizeNTF you can ask it keep all the zeros on dc or to optimize them.

Bupesh

 

[jayanth.neo]

delta loop design

Hi,

if you simulate the DS toolbox and get the value of coefficients, the value of g1 is very small in the order of 10^-4 and can usually be neglected for the above structures u mentioned.

 

[ookok]

there is no g for CIFB
g is for CRFB

G can be used to spread zeros, which can't be done by using CIFB.
please read the book carefully.