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Regarding Sigma Delta Modulator

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arp

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Hi,

I am designing a 2-1 cascaded sigma delta modulator using MATLAB simulink.
I felt this is a silly question but requires your help..

I caluclated the coeffficients of each integrator and I am getting doubts in digital error cancellation logic...
how can i implement this logic block in Simulink...

first of i started using discrete filters, unit delay for that logic but i think its wrong to use those blocks in the digital logic...

can anyone please help me regarding this.....

thank you in advance...

arp
 

**broken link removed**
 

Hi paladinzlp,

I am not able to understand from the site..
can you please explain it for me.....

thanq
arp
 

I think you should have no problem to implement the error cancelation in Simulink using the standard blocks. But first one question. Do you use a continuous time or discrete time loop. If it the first you need to find the equivalent discrite time cancelation.
Here the step I would follow:
- calculate the cancelation logic TF (should be easy, generally like 1-z^(-1))
- use the transfer function block of Simulink (I hope it's the correct name) from the "discrete" blocks
I've done it only once, but I didn't have specific problem.
By the way you can implement the decimation filter in the same way. I think the are some information on the Matlab web page about digital filters and Simulink.
Regards
 

arp, i met the same problem with you ,how to implement the digital logic of sigma delta in the simulink ?for example ,the quantizer,the acumulator,the unit delay......can someone give me a sample ,thanks
 

jerryhuang, the quantizer you can use the "sign", the acumulator is "Discrete Integrator", the unit delay is "delay".
 

I assume you are designing discrete-time cascaded sigma-delta modulator. It has no problem to implement all the blocks in Simulink. For the error cancellation logic, just use the gain element and delay element, together with summer and you are done. I don't see why this is a problem for you.
 

designing discrete-time cascaded sigma-delta modulator
 

simulink is a tool for instinct just type what you want and click search, you will get it .
 

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