DIGITAL FILTER CIRCUIT AND DIGITAL FILTER PROCESSING METHOD

摘要

A digital filter circuit of the present invention is provided with the following: a fast Fourier transform (FFT) circuit (13) for converting a time-domain complex-number signal into a frequency-domain signal; an I/Q separation circuit (15) for separating the frequency-domain signal into a first frequency-domain signal corresponding to the real part of the time-domain complex-number signal and a second frequency-domain signal corresponding to the imaginary part of the time-domain complex-number signal; a filter circuit (21) for filtering the first frequency-domain signal; a filter circuit (22) for filtering the second frequency-domain signal; an I/Q combination circuit (16) for generating a third frequency-domain signal by combining the output of the filter circuit (21) and the output of the filter circuit (22); a filter circuit (23) for filtering the third frequency-domain signal; and an inverse Fourier fast transform (IFFT) circuit (14) for converting the output signal of the filter circuit (23) into a time-domain signal.