US Patent 7461114 Fourier transform apparatus

A Fourier transform apparatus whose pipeline width is independent of transform point number of individual pipeline FFT circuits in each stage and composed of a preceding stage and a succeeding stage. Each of the stages includes M(power of 2)-point radix 2 pipeline FFT circuits each having two-parallel inputs/outputs in a number of a (divisor of M) which are equal in respect to the transform point number and data permutating means for data supply to the transform means of each stage so that the pipeline width of the Fourier transform apparatus is made independent of the transform point numbers of the individual pipeline FFT circuits in each stage.