Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

Gate level Simulation passes but design fails on target borad

Hello, I am implementing a filter (2nd order) in Quartus Stratix II device running at 500KHz. I simulated the design using ModelSim. My Target hardware consists of stratix II device. Input...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

After looking back at some of the figures in this post, it seems I assumed sampling freq was 100K but actually you are saying it is 500KHz. Thus the two filters notch point must be moved 5 time higher (100Hz => 500Hz...etc).

So obviously both my analysis and your friend's point to same response but is in conflict with your expectations of actual frequency. Anyway, it is a not problem, all you need is look at the frequency point that corresponds to 5 times our posted figures.

The rule is simple: freq out = normalised freq * sampling freq/2.

normalised freq is 1.0 at half sampling freq.(in matlab functions)

A good indicator that your filter is wrong is if output is weird provided input freq is a regular sine.