Efficient design of ladder-based transconductor-capacitor filters and equalisers

Abstract

The paper outlines matrix methods for ladder-based transconductor-capacitor filter and equaliser design and a theory for the canonical realisation of ladder-based transconductor-C filter is presented. A filter and equaliser compiler based on the proposed method is described. As an example, a fifth-order elliptic lowpass filter and a sixth-order group delay equaliser have been designed. It is shown that the order of the equaliser can be reduced by application of special techniques for the approximation of the filter transfer function. A comparison of sensitivity between a cascade of biquadratic stages and the ladder-based realisation is given. Lower sensitivities to component tolerance for both filter and equaliser are displayed by the ladder-based design. Test results from the fabricated filter and equaliser are also given.