Apparatus and method for variable fast fourier transform

An apparatus for performing a variable fast Fourier transform (FFT) algorithm, comprising:

• two n-point FFT processors (n is a specific number) each of which selects an FFT twiddle factor for n-point input data or 2n-point input data, and performs fast Fourier transform;
• an input data aligning unit that classifies the 2n-point input data and alternately inputs the classified data to the two n-point FFT processors;
• a butterfly operation unit that receives data obtained by performing fast Fourier transform on the 2n-point input data from the two n-point FFT processors and performs a butterfly operation on the received data;
• and
• an output data aligning unit that receives the operated data from the butterfly operation unit and aligns the received data in an output order.

A variable fast Fourier transform method using an apparatus for performing fast Fourier transform (FFT) on n-point input data (n is a specific number) or 2n-point input data, comprising:

• determining whether the n-point input data or the 2n-point input data is supplied;
• when determined that the n-point input data is supplied, selecting a twiddle factor for the n-point input data;
• when determined that the 2n-point input data is supplied, selecting a twiddle factor for the 2n-point input data;
• and
• performing fast Fourier transform using the selected twiddle factor.

A variable fast Fourier transform method using an apparatus for performing fast Fourier transform (FFT) on n-point input data (n is a specific number) or 2n-point input data, comprising:

• determining whether the n-point input data or the 2n-point input data is received;
• when determined that the n-point input data is received, performing the fast Fourier transform using a twiddle factor for the n-point input data to generate a first output;
• and
• when determined that the 2n-point input data is received, performing the fast Fourier transform using a twiddle factor for the 2n-point input data to generate a second output.