Patent ID: 7391632

Claim:
An Fast Fourier Transform (FFT) apparatus selectively performing a Fast Hadamard Transform (HFT), comprising N signal processing means connected in serial according to a 2 N length of a code, where N is a positive integer, wherein each of N signal processing means includes: a storing means for temporally storing and outputting an output signal of a first multiplexing means; an adding means for adding the output signal of the storing means and an input signal; a subtracting means for subtracting the input signal from the output signal of the storing means; a multiplying means for multiplying a phase coefficient to the output signal of the subtracting means and outputting the multiplied signal; a first multiplexing means for selecting one of the output signal of the multiplying means and the input signal; and a second multiplexing means for selecting one of the output signal of the adding means and the output signal of the storing means, wherein 2 nd to N th signal processing means receive an output signal of a second multiplexing means of (N−1) th signal processing means and N th signal processing means includes 2 N−1 storing means connected in serial.