DSP Builder for Intel® FPGAs (Advanced Blockset): Handbook

ID 683337
Date 12/12/2022
Public

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15.3.21. Streaming FFTs (FFT2, FFT4, VFFT2, and VFFT4)

The FFT2, FFT4, VFFT2, and VFFT4 blocks are low-level blocks that implement streaming FFTs.
Table 141.  Parameters for the FFT2, FFT4, VFFT2, and VFFT4 Block
Parameter Description
iFFT true for an iFFT, otherwise false. FFTT4 and VFFT4 only.
Bit reversed input true for bit-reversed inputs. FFT4 and VFFT4 only.
Stages before this The number of stages to the left of this FFT.
Stages after this The number of stages to the right of this FFT.
Input type The type of the input signal. For example: fixdt(1,16,15).
Use faithful rounding true to use faithful rather than correct rounding. Fixed-point FFTs ignore this parameter.
Table 142.  Port Interface for the FFT2, FFT4, VFFT2, and VFFT4 Blocks
Signal Direction Type Description
v Input Boolean Valid input signal.
d Input Any complex type Complex data input signal.
drop Input uint(k) for some k Total number of FFT stages to bypass.
qv Output Boolean Valid output signal.
q Output Any complex type Complex data output signal.
qdrop Output uint(k) for some k Total number of FFT stages to bypass.