Special FIR and IIR BI Notch Filters

A methodology for designing FIR bi notch filters derived from second order prototype IIR notch filters is suggested. A special case when two notch frequencies omega₁ and omega₂ are such that [(cos omega1)(cos omega₂) = -1/2] has been discussed. The IIR bi notch filter design for this special case results reduction in the number of multipliers without affecting the response of the desired notch filter. For the referred condition, the required design weights of FIR bi notch filter reduce to almost half in number resulting in reduced computations.