New designs of low/high-pass and mid-pass/stop FIR Digital filters

摘要

New designs of highly efficient low/high-and mid-pass/stop (centre-symmetric band-pass/stop) FIR non-recursive digital filters are presented. The designs are based on the modulation property of DFT, applied to the already presented MAXFLAT halfband low-pass filters. The presented filters have ex- plicit formulas for their tap-coefficients, and therefore are very easy to design. They have highly smooth frequency response and wider transition regions like MAXFLAT filters. The design formulae are mod- ified to give new classes of low/high-and mid/pass/stop filters, for which, like in equiripple filters, the transition bandwidth can be reduced by increasing the size of ripple on magnitude response. It is shown, with the help of design examples, that the performance of these filters is comparable to that of equiripple filters.