A highly-programmable Finite Impulse Response (FIR) digital filter overcomes the limitations of conventional configurations. Specifically, a compound FIR filter configuration is provided, offering the advantages of heightened programmability in both transfer function coefficients hf, hg and in degree of interpolation; distribution and sharing of resources between F and G filter portions, mode-switching capability between high-pass and low-pass modes, and programmable truncation/saturation.