Cascade realisation of the irrational immittance s¿

The paper considers the realisation of immittances of the type s¿ by a cascade connection of an infinite number of lumped two-port networks. The number and the location of the transmission zeros of any two-port are independent of any other two-port. The only restriction is that the transmission zeros cannot lie on the negative real axis. An expression for the input impedance of a finite number of terminated two-ports is obtained. This is used to obtain an immittance function approximating ¿s over a large bandwidth.