Efficient rational sampling rate alteration using IIR filters

The problem of changing the sampling rate of a signal by a rational factor of L/M is discussed. It is shown that infinite impulse response (IIR) filters can be efficiently implemented using the polyphase decomposition. The computational cost of the recursive and nonrecursive parts of the interpolation filter are considered separately, and a gain in efficiency of a factor of LM/(L+M-1) is achieved for the recursive part. This gain is only significant when both L and M are larger than one.