DESIGN OF VARIABLE IIR DIGITAL FILTERS USING EQUAL SUBFILTERS
Georgi K. Stoyanov, Ivan M. Uzunov, Masayuki Kawamata · 2000
A new approach to design variable IIR digital filters by using a cascade of N equal individual filters of any order n is proposed in this paper. First, the approximation method for lowpass filter specifications is outlined, then the general limitations of the method are investigated and a compact formula is derived. Next, the limitations for the main canonic approximations are investigated and convenient expressions are obtained. New first- and second-order filter sections, permitting very easy tuning of the cutoff frequency, are developed and the design and tuning strategies for highpass, bandpass and bandstop filters are proposed. Finally design examples are given and the superiority of the new method compared to other known is demonstrated experimentally. 1.