Low-pass filters of even orders with equal ripple delay and Chebyshev stopband attenuation

A class of low-pass filter functions of even degree is presented having equal ripple delay response and Chebyshev stopband attenuation. A special type of equal ripple delay approximation, referred to as the constrained Chebyshev approximation, that was previously employed to construct filter functions of odd degree, is modified so that it can also be used advantageously in the design of even-ordered lowpass filters. A comparison of results reveals that by this method a considerable amount of performance improvement of the resulting filter can be obtained. Tables are presented giving the zero and pole locations of these filters for n = 4, 6, 8 and 10 together with some other important parameters both in the frequency and in the time domain.