Optimal design of variable fractional-delay digital filters

This paper presents a closed-form solution for obtaining the optimal coefficients of variable FIR filters with continuously adjustable fractional-delay (FD) response. The design is formulated as a weighted-least-squares (WLS) approximation problem without discretizing the frequency and fractional-delay parameters. Compared with the existing WLS method, the discretization-free one can yield a closed-form optimal solution with considerably reduced computational complexity.