Sigma-Delta modulator and demodulator simulation in Simulink

[sehun1119]

simulink for sigma delta converters

Hi, all

I am studying for sigma-delta modulation and trying to build a simple second-order sigma-delta modulation in Simulink as a start.

I have gone through a few tutorials and papers, and here is my status.

I put a sine wave as an input and simply add integrators using "unit delay" with feedbacks and 1-bit quantizer as the references that I found show. For the input sine wave, I use a frequency of 2*pi*406.25 and sample time of 1/1024e3.
(I attached a picture of simulink)


My questions are:

1) how do I determine the coefficients in the modulation loop? I guess that is too obious so that I could not find information from any references or I have not searched enough.

2) With any values of coefficients that I chose, I somehow obtained some digital outputs after the sigma delta modulator. Now, I would like to reconstruct the input signal by adding decimators after the modulator output. What rules should I follow?

3) To my understanding by now, the sigma-delta modulator will produce 1-bit digital outputs (2 levels). How is the resolution determined? Is the resolution of this modulation depending on the decimators in demodulation after the modulator? (any relation between decimation factor and resolution?)

Any help or comments would be very appreciated.

Thank you in advance.

 

[gevy]

Re: Sigma-Delta modulator and demodulator simulation in Simu

You must read books

Delta-Sigma Data Converters by NORSWORTHY, SCHREIER, TEMES
Design of LV LP CMOS Delta-Sigma ADC by PELUSO, STEYAERT, SANSEN
Design Of Modulators For Oversampled Converters by Wang, Harjani
Design-of-low-voltage-low-power-sigma-delta-modulators by Rabii, Wooley
Oversampled ADC by Brandt
Oversampled Delta-Sigma Modulators - Analysis, Applications and Novel Topologies by Kozak, Kale
Oversampled Sigma-Delta Converters by Baschirotto
Principles of Sigma-Delta Modulation for ADCs by PARK
Sigma-Delta Modulators for Integrated Circuit ADCs by Steiner (thesis)
Top-Down Design of High Performance Sigma-Delta Modulators by Medeiro and others
Understanding_Delta_Sigma_Data_Converters by Schreirer, Temes