Modeling of Sigma Delta ADC in Simulink

[meghna]

Hi,
I am designing a second order continuous time sigma delta modulator having one bit quantizer. I am modeling it in simulink to see STF and NTF. When parasitic caps are also included in the system, it becomes a fourth order system. Somehow, I am not getting the correct STF (Signal Transfer Function) at higher frequencies (near Fs/2) when it is fourth order.

Can somebody tell me how to model high order polynomials accurately in Simulink.

Thanks & Regards
Meghna

 

[northeast1]

Hi,
I am designing a second order continuous time sigma delta modulator having one bit quantizer. I am modeling it in simulink to see STF and NTF. When parasitic caps are also included in the system, it becomes a fourth order system. Somehow, I am not getting the correct STF (Signal Transfer Function) at higher frequencies (near Fs/2) when it is fourth order.

Can somebody tell me how to model high order polynomials accurately in Simulink.

Thanks & Regards
Meghna

You can go to matlab web to download the ADC model