FFT DEVICE AND METHOD FOR PERFORMING A FAST FOURIER TRANSFORM
An FFT device for performing a Fast Fourier Transform (FFT) of an operand vector of length N is described. The FFT device comprises: a control unit arranged to control a sequence of transformation rounds, the transformation rounds including two or more FFT rounds, wherein the FFT rounds include a wi...
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Zusammenfassung: | An FFT device for performing a Fast Fourier Transform (FFT) of an operand vector of length N is described. The FFT device comprises: a control unit arranged to control a sequence of transformation rounds, the transformation rounds including two or more FFT rounds, wherein the FFT rounds include a window-FFT round or the transformation rounds further include a window round, wherein each transformation round is arranged to be carried out in a sequence of N/M successive operations, each operation transforming a subvector of length M of said operand vector into a corresponding transformed subvector of length M; and a coefficient unit for providing transformation data; and a transformation unit arranged to receive, for each of said transformation rounds, transformation data from the coefficient unit, the transformation data depending on whether the respective transformation round is an FFT round, a window-FFT round, or said window round, and to perform the respective linear transformation on the basis of the transformation data. The transformation data for an FFT round comprises a set of twiddle coefficients, the transformation data for a window-FFT round comprises a set of modified twiddle coefficients, and the transformation data for a window round comprises a set of window coefficients. The coefficient unit comprises or is integrated in a Random Access Memory (RAM) unit, the RAM unit comprising a set of memory blocks, each memory block being readable as a whole within a single clock-cycle. The set of memory blocks comprises: a subset of window memory blocks, each of said window memory blocks providing the window coefficients for a respective operation of the window round, or a subset of window-FFT memory blocks, each of said window-FFT memory blocks providing the modified twiddle coefficients for a respective operation of the window-FFT round. The set of memory blocks further comprises a subset of FFT memory blocks providing the set of twiddle coefficients or a reduced set of twiddle coefficients. |
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