Design of Wide-Band Asymmetric Hybrid Ladder Filters

In this paper, a new type of hybrid ladder filter is presented to be used in asymmetric wide-band filter designs. The concept is based on simple filter stages that may be cascaded in a ladder-type topology. The single filter stages each employ acoustic-wave resonators and other lumped elements in certain combinations that allow for steep filter skirts on one side of the passband and theoretically unlimited bandwidth. An algorithm for the design of arbitrarily-wide-band filters with fixed properties of acoustic-wave resonators is given. Furthermore, simulation and measurement results of a prototype filter stage are presented, that prove the concept to be feasible.