Lumped-element-based single/dual-passband analog filters using signal-interference principles

An original type of lumped-element analog filters based on signal-interference techniques is proposed in this paper. To this aim, a novel class of two-path transversal filtering section shaped by a lumped-element quadrature power coupler arranged in reflection mode is devised as basic building block. Thus, under feedforward signal-interaction effects generated in this circuit network, high-performance filtering functions can be produced. As synthesis examples, two different multi-stage designs corresponding to ultra-wideband single-band and dual-band bandpass filters are demonstrated. Furthermore, for the previous ultra-wideband bandpass filter example, two alternative implementations at the layout level are developed for practical verification.