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Simulators >> System Simulators >> How to build up a simulink model for simulating PSD of a Sigma Delta Modulator
https://designers-guide.org/forum/YaBB.pl?num=1251790047

Message started by Esther on Sep 1^st, 2009, 12:27am

Title: How to build up a simulink model for simulating PSD of a Sigma Delta Modulator
Post by Esther on Sep 1^st, 2009, 12:27am

Hi, All,

I am designing a fractional N PLL. Currently I am trying to simulate noise of each block in the PLL.

For SD modulator, simulation of it is my problem. I build a structure in simulink. It is a Mash1-1-1. then I do transient simulation. The output of it is -3,-2,-1,0,1,2,3( i don't know why 4 has never happened??).. Then I put a FFT spectrum block at it's output. BUt i can see nothing. the Spectrum gave me nothing.. what's wrong? Or is my method is not correct?

Thank you in advance!

Title: Re: How to build up a simulink model for simulating PSD of a Sigma Delta Modulator
Post by ywguo on Sep 2^nd, 2009, 8:14pm

Generally, I don't know what's wrong with your simulink model. But why do you expect the output stream contains code 4? I have a MASH 1-1-1 model, too. It works fine.

Can you put your model in the post?

Yawei