Method and apparatus for digital up-down conversion using infinite impulse response filter

An apparatus for performing digital up-down conversion for a frequency conversion in a mobile communication system using plural frequency conversion, the apparatus comprising:

• a magnitude response unit for Infinite Impulse Response (IIR)-filtering an input signal by a magnitude response IIR filter having a filter coefficient calculated by a Levinson polynomial, wherein the filter coefficient of the magnitude response IIR filter has a same magnitude response as in Finite Impulse Response (FIR) filtering and secures stability of the magnitude response IIR filter;
• and
• a phase compensation unit for receiving the IIR filtered signal from the magnitude response IIR filter, and for performing IIR filtering by a phase compensation IIR filter having a filter coefficient compensating for a non-linear phase to a linear phase,
• wherein the magnitude response unit receives a magnitude response of the input signal filtered by the FIR filter to calculating an impulse response signal using an Inverse Fast-Fourier Transform (IFFT), determines an order of the magnitude response IIR filter and calculates an autocorrelation sequence of the calculated impulse response signal, calculates a Levinson polynomial using the calculated autocorrelation sequence and checks security of stability according to the computed Levinson polynomial, and determines the stable filter coefficient of the magnitude response IIR filter according to the Levinson polynomial when the security of stability is achieved.