Bandwidth-enhancement g(m)-C filter with independent omega(O) and Q tuning mechanisms in both topology and control loops

Abstract

This paper deals with the proposal of a new topology for a gm-C continuous time filter which allows the adjustment and tuning of its characteristic parameters (ωO and Q) in an independent way (without cross-tuning), thereby extending the Q range of the filter for a particular ωO value. Additionally a comparison of three different Q-tuning algorithms is presented. It is shown that an LMS-based Q-control strategy allows to overcome the intrinsic dependence between the Q and ωO tuning oops. The combination of both the proposed filter topology and the selected control loop algorithms results in an enhanced ransient performance as well as an improvement in terms of cross-detuning.