FBAR LADDER FILTER AND METHOD OF GROUNDING OF FBAR LADDER FILTERS

摘要

An FBAR ladder filter which may yield less degradation in the stopband near the passband edges than conventionally grounded FBAR ladder filters. For that purpose a thin film resonator (FBAR) ladder filter having a plurality of serially-coupled FBAR elements (307,309,317,319), each serially-coupled FBAR element including an upper metal electrode and a lower metal electrode, and a plurality of shunt-coupled FBAR elements (310,320), each shunt-coupled FBAR element including an upper metal ground electrode providing a ground node and a lower metal electrode, is provided with at least one capacitor element (330) including an upper metal electrode and a lower metal electrode, wherein each capacitor element is serially coupled between two ground nodes so that the inductive coupling of the shunt-coupled FBAR elements is compensated. IMAGE