**Part Number:**TIDA-00778

Hello,

In TIDA-00778 design, we can see a anti aliasing filter with cutoff frequency of 15 MHz. The picture below shows this filter:

Also, the following picture shows the ADC input impedance model for TMS32028027F.

So, I have some questions about that:

1-)How do you choose the 15 MHz for cutoff frequency of anti aliasing filter? as far as I know, the cutoff frequency of anti aliasing filter should be smaller than half of sampling frequency and the current sampling frequency in FOC algorithm is 10-20 kHz. so the cutoff frequency of anti aliasing filter should be smaller than 5-10khz.

2-)How do you calculate the 15 MHz?

3-)When we need this filter?

Regards,

Mohammad.