For a full description of the models, refer to the September 2007 MATLAB Digest article.

http://www.mathworks.com/company/newsletters/digest/2007/sept/sigmadelta.html

We present a series of Simulink models to design a high-level behavioral model of a Sigma-Delta ADC. The high-level behavioral model has an Analog section and a Digital section that comprises a digital filter. We partition the digital filter into three cascade filters that use a total of 10 times less filter coefficients than the original filter. We then elaborate the first filter in the cascade in such a way that it requires no multiplications for implementation. We convert our design to fixed-point. We then proceed to generate VHDL code for our elaborated filter using Simulink HDL coder. This is an example of Model-Based Design.