Abstract: Digital Down Converter (DDC) is one of the key technologies in Software Defined Radio (SDR), especially in the Intermediate Frequency (IF) digitization systems. Accordingly, this study introduces a multi-stage design of IF DDC which begins with the performance indication determination, followed by two decompositions of multiple filter combinations, then the comparison between these two decompositions are presented to choose a better decomposition, finally the fix-point bit error rate simulation is carried out and the result shows that the proposed DDC design yields excellent performance close to the theoretical Bit Error Rate (BER) bound.