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Design >> Analog Design >> two issues in sigma delta modulator
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Message started by trashbox on Oct 11^th, 2007, 2:08am

Title: two issues in sigma delta modulator
Post by trashbox on Oct 11^th, 2007, 2:08am

Hi guy,
I'm studying the MASH sigma delta modulator and run into two issues, please refer to the attached figure:
1) In such a 2-1-1 sdm, how can I derive the signal transfer function Y(z)? The figure gives the result, but I can not get it from this sdm.
2) In the cancellation logic part, how can I derive the results shown in the form on top right corner? In other words, why should g2' equal with 2g1'g2? Why H1(z)=Z^-1?

Would you please give me any hints or key derived progress? Thank you very much.
trashbox

Title: Re: two issues in sigma delta modulator
Post by bananawolf on Nov 16^th, 2007, 7:20pm

The gain for the single-bit quantizers in the first two stages can be anything.
I think this can help u solve the problem.