An efficient procedure for the design of a large class of analog and digital filters

A general procedure is described for the approximation in the Chebychev sense of an arbitrary attenuation curve in the passband(s) and in the stopband(s), by an analog or digital transfer function. Both the analog and digital cases are reduced to a common optimization problem which is solved by the efficient Remez algorithm working with the transmission zeros and attenuation zeros. Some of the transmission or attenuation zeros can be fixed by the user at prescribed frequencies. Digital filters with a numerator of lower degree than the denominator can also be designed. The method has been implemented on a PC and is illustrated by some examples.<
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