Maximally flat approximation of lowpass RC active filters with multiple real pole

A new maximally flat approximation criterion is proposed to realise lowpass RC active filters with a reduced number of amplifiers with respect to the classical Butterworth polynomials. This improvement is obtained by adding a multiple real pole and reducing the number of the complex pole pairs. The cascade connection of 3rd-order blocks allows the realisation of filters with fewer sections (fewer o.a.s) with respect to the commonly used cascade connections of 2nd-order blocks.