Patent ID: 7461114

Claim:
A Fourier transform apparatus for performing discrete Fourier transform, characterized in the said Fourier transform apparatus comprises transform means of a preceding stage including a number a of M-point radix 2 pipeline FFT circuits each having two parallel inputs/outputs, wherein M (=2 m , m>=2) represents a maximum number of points for transform and a, which is not less than two and is equal to or smaller than M/2, represents a divisor of said maximum transform point number M, first data supply means for supplying data sets each consisting of M data mutually separated by M points, on an a-by-a basis, in parallel on a two-by-two data basis in each set to said transform means of a preceding stage from input data, transform means of a succeeding stage including a same number of M-point radix 2 pipeline FFT circuits as the transform means of said preceding stage, each of said FFT circuits having two parallel inputs/outputs, second data supply means for supplying data sets, each consisting of M data mutually separated by M points, on an a-by-a basis, in parallel on a two-by-two data basis in each set to said transform means of a succeeding stage, from said transforming result of transform means of a preceding stage and twiddle factor multiplication means including 2a complex multiplication circuits and a factory memory for supplying twiddle factors, provided between said second data supply means and the transform means of said succeeding stage for multiplication of twiddle factors.