FIR filter with variable fractional delay and phase shift: Efficient realization and design using reweighted l1-norm minimization

This paper introduces a finite-length impulse response (FIR) digital filter having both a variable fractional delay (VFD) and a variable phase shift (VPS). The realization is reconfigurable online without redesign and without transients. It can be viewed as a generalization of the VFD Farrow structure that offers a VPS in addition to the regular VFD. The overall filter is composed of a number of fixed subfilters and a few variable multipliers whose values are determined by the desired FD and PS values. It is designed offline in an iterative manner, utilizing reweighted l₁-norm minimization. This design procedure generates fixed subfilters with many zero-valued coefficients, typically located in the impulse response tails.