Date: Feb 26, 2013 10:35 AM
Author: fl
Subject: How to get the FFT cycles: N>8  Tcycle =  3N/2-2 + log2(N)*(N/2+3);

I use Simulink FFT block to generate HDL code. The help says:

N>8 Tcycle = 3N/2-2 + log2(N)*(N/2+3);

I see that it uses 4 multipliers in the butterfly. I would like to know the meaning of the above equation. 3N/2-2 is the prelog?

For each cyle, what is the cycle number? It uses 4 DPRAM. I guess that it should have a number account for the DPRAM cycles, some delay register cycles, but I cannot find that number in the above eqaution. Could you help me?