Designing FIR filters with variable notch

In this paper, we propose a transfer function of filters which does not change filter characteristics even if notch frequency changes. A change in filter coefficient which depends on change in a notch frequency is approximated by the polynomial which used a variable parameter. In this method, the minimization problems for the coefficients of the filter with a variable notch are formulated as semidefinite programming (SDP) in the frequency domain. Moreover we present that the proposed VDF can be implemented using the Farrow structure suitable for high-speed signal processing.