Unified FFT Intel® FPGA IPs User Guide

ID 683366
Date 9/30/2023
Public

1.5. FFT Spectrum

The Unified FFT IPs produce a double-sided frequency spectrum.

The frequency bin 0 (first) contains the DC signal. In natural order, frequency bins 1 to FFT_size/2 contain the positive frequencies in increasing order up to the Nyquist frequency. In natural order, the frequency bin (FFT_size/2) + 1 contains the most negative frequencies equal in absolute value to positive frequencies in bin (FFT_size/2) -1. The negative frequencies decrease in absolute value with increasing bin numbers. The frequency bin FFT_size -1 contains the least negative frequencies equal in absolute value to positive frequencies in bin 1.

For inverse FFTs the input spectrum is expected in this format.