An improved weighted least-squares design of FIR digital filters with variable fractional delay
Wu-Sheng Lu, Tian–Bo Deng · 2003
Digital filters capable of changing their frequency response characteristics are often referred to as variable digital filters (VDFs) and have found uses in a number of digital signal processing applications. An important class of VDFs is the digital filters with variable fractional delay. This paper describes an improved WLS design for variable-fractional-delay FIR filters, which offers improved performance of the filters obtained with considerably reduced computational complexity compared to a recently proposed WLS design method. The design improvement is achieved by deriving a closed-form formula for evaluating the WLS objective function. The formula facilitates accurate and efficient function evaluations as compared to summing up a large number of discrete terms, which would be time consuming and inevitably introduce additional errors into the design.