Doubt on Sinc3 filter

Hi,

We are trying to design a second order delta sigma modulator. As part of it, we want to design a Sinc3 filter with a decimation factor of 300. Sampling frequency is 600KHz and Nyquist is 2Khz.

We were trying to simulate sinc3 filter in matlab simulink. As you may know, sinc3 filter consists of 3 integrators followed by 3 differentiators. Each integrator & differentiators are designed using a DFF and a summer. We have modeled it in simulink, but while trying to run it, we are getting some error. The error says "Propagation of the output data type for Sum resulted in a data type error. Using the internal propagation rule, data type of the output was determined, but this data type disagreed with the data type that had already been set for this signal. The conflicting data type would have been set by a destination whose input is connected to the signal"

We are unable to attach the screen shot.

Please help us solve it. Or if you have some matlab code for sinc3 filter, please share.

Thanks in advance for all replies.

Regards, abdj

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/7924-where-can-i-upload-images-and-files-for-use-on-matlab-answers