Design tables for active filters having 2nd- and 4th-order chebyshev responses in pass and stop bands

The paper presents tables which facilitate the design of low-pass and band-pass RC active filter networks having Chebyshev 2nd- and 4th-order response in both pass and stop bands. The synthesis method used is that due to Yanagisawa. This yields a network containing a current-reversing negative-impedance convertor and passive RC networks to obtain a required voltage transfer function. An optimum polynomial due to Sipress is used in the synthesis, giving the minimum sensitivity of the filter response to errors in the transfer characteristic of the negative-impedance convertor. The design procedure using Zolatarev fractions is outlined, and the method for obtaining required amplitudes of ripple in the pass band is explained. The selection of certain ripple amplitudes requires a change in the network configuration. The Yanagisawa-synthesis procedure is discussed briefly, the use of the design tables is explained and an example is given. Experimental results obtained with 2nd- and 4th-order low-pass filters are shown and are compared with the theoretical curves.