Patent ID: 6240062
Filing Date: 2001-05-29
Classification: G06F

Abstract:
A fast FOURIER transform calculating apparatus for performing a butterfly calculation on input data, said fast FOURIER transform calculating apparatus comprising:input means for receiving an instruction signal which provides an instruction to perform a butterfly calculation of a cardinal number of two or a butterfly calculation of a cardinal number of four;a selector operable to select predetermined data in accordance with the instruction signal;a switch operable to switch the predetermined data between a real number portion and an imaginary number portion in accordance with the instruction signal; anda sign inversion device operable to invert a sign of the real number portion or the imaginary number portion of the predetermined data in accordance with the instruction signal,wherein a pair of butterfly calculations of a cardinal number of two are simultaneously performed in a case where the instruction signal provides an instruction to perform a butterfly calculation of a cardinal number of two, and a single butterfly calculation having a cardinal number of four is performed in a case where the instruction signal provides an instruction to perform a butterfly calculation of a cardinal number of four.