An analog-to-digital converter includes a delta-sigma modulator (10), having the output thereof filtered by a digital filter section. The digital filter section includes a first fixed decimation filter (12) followed by a variable decimation filter section (14) and an output low-pass filter section (16), having a fixed decimation ratio. The fixed variable decimation filter section (14) includes a single FIR filter (24) that has data processed therethrough with different sampling rates. A recursive controller (26) receives an external configuration input to determine the number of passes through the filter (24) that are required to provide the desired decimation ratio.