Digital decimation filter having finite impulse response (FIR) decimation stages

A digital decimation filter having Finite Impulse Response (FIR) decimation stages provides improved performance over a Hogenauer decimating filter. The filter comprises multiple integrator stages followed by multiple FIR decimating stages. The zeros of the filter are tunable by adjusting the integer coefficients of the FIR stages providing tunability of the cut-off response, as opposed to the fixed sinc response of the Hogenauer filter. As a result, the number of required stages for a particular steepness is reduced, dramatically reducing the amount of digital circuitry required to implement a particular filter design. The improved filter is especially suitable for use in digital intermediate frequency (IF) stages in receivers, and for code-based applications where selectable decimation rate is desired and a fast multiply is not available.