Selective filters using least-mean-square approximation technique

A new clan of all-pole lowpass filters having a flat magnitude characteristic at the origin and at a frequency ¿0 in the pass-band is presented. The remaining degree of freedom is used to minimise the characteristic function over the passband using least-mean-square norm. It is shown that the magnitude characteristic of new filters is superior to those for the Butterworth and transitional Butterworth-Cheby¿shev filters, both in the passband and in the stopband.