Design of Digital Butterworth Notch Filters

Along with the development of digital technology,digital filters are widely used in many fields,this paper introduces how to design a IIR digital notch filters in matlab environment.The design of digital notch filters can be achieved through three steps:firstly,the design of analog low-pass filter;secondly,it is analog low-pass to analog band stop filter conversion;at last,using the bilinear transformation make the analog notch filters change into digital notch filters.The paper also introduces how to design the transfer function of the digital notch filters using all the zeros and farthest points at the same time,it also introduces the program of the digital notch filters under Butterworth analog low-pass prototype.