This version (18 May 2021 08:43) was approved by John Joseph.The Previously approved version (02 Jul 2020 15:41) is available.Diff

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Inverse FFT



N-point IFFT is performed on the samples, where MaxN is configurable and should be a power of greater than or equal to N mentioned in the preceding FFT. The twiddle coefficients are calculated within the code and input of IFFT are PCMx samples, the BlockSize of which 3 * Schematic BlockSize. The first Schematic Block Size number of samples in a PCMx input contains the header information carried from the previous Module (say in this case FFT). Only when the PCMx type matches, IFFT is performed and output is given as PCM samples. The header information contains fields such as PCMx type (Windowing done), N, Count (if N>Schematic BlockSize).

IFFT Windowed

In the Windowed version, windowing is done in the FFT Module for 2N samples. Overlap and add for N samples are done at the IFFT end. Hence the output is delayed by N samples. Since memory size depends on the value of MaxN, downloading the Schematic (Link-Compile-Download) is necessary when MaxN value is changed.


Real IFFT is a block processing module which computes the IFFT of real signals.

Complex IFFT

Complex IFFT is a block processing module which performs N point complex IFFT of the input signal, where N stands for BlockSize.


  • IFFT
  • IFFT Windowed
  • Real IFFT
  • Complex IFFT

Targets Supported

Name ADSP-214xx ADSP-215xx/SC5xx ADAU145x/146x
————————————-- ——————-- ——————————-- —————————-
IFFT Windowed NA B NA
Complex IFFT NA NA B



Name Type Description
———————- ————-- ———————-
Input0 PCMx First Input channel (IFFT and IFFT Windowed)
Input0 PCMx Second Input channel (IFFT and IFFT Windowed)
Input Audio Input channel (Real IFFT)
Input Complex Input channel (Complex IFFT)


Name Type Description
———————- ————-- ———————-
Output0 Audio First Output channel (IFFT and IFFT Windowed)
Output0 Audio Second Output channel (IFFT and IFFT Windowed)
Output Audio Output channel (Real IFFT and Complex IFFT)

Configurable Parameters

GUI Parameter Default Range Function Description
—————————————- ———————- —————— —————————————-
Max N 64 16 - 1024 Max N-point IFFT to be performed. This should be value greater than “N” mentioned in the preceding FFT Module. This parameter is required by the Module for memory allocation.

DSP Parameters

Name Description ADSP-214xx/215xx/SC5xx ADAU145x/146x
—————————- ————————————————-- —————————————- ———————————-
Max N Max N-point IFFT to be performed Integer NA
resources/tools-software/sigmastudiov2/modules/advanceddsp/inversefft.txt · Last modified: 12 May 2021 13:21 by John Joseph