poly - phase filters are used to offer an efficient and low complexity solution to rate conversion . however , they suffer from inflexibility and are not easily reconfigured . a novel design for rate converters employ poly - phase filters but utilize interpolation between filter coefficients to add flexibility to rate conversion . this interpolation can be implemented as an interpolation of the poly - phase filter results . additional approximations can be made to further reduce the amount of calculations required to implement a flexible rate converter .