Non-Standard Functions Enabling Feasible Microwave- Acoustic Ladder Filters

Abstract

This paper explores how acoustic wave (AW) ladder filter can trade the location of the reflection zeros (RZs) in exchange for greater flexibility to accommodate technological constraints. The method, that is leveraged in a robust and mathematically exact synthesis methodology, proposes arranging the RZs in the complex plane in such a way the device performs an equiripple shape in the passband but depicting shallow RZs in comparison to the deep RZs of the classical Generalized Chebyshev (GC) response. A synthesis example validates the pro-posal reaching an evenly-distributed electromechanical coupling coefficient among all resonators while depicting an out-of-band (OoB) rejection close to that achievable with an ideal equiripple response but without adding external reactive elements.