Attenuation pole type monolithic crystal filter

Claim 1

An attenuation pole type monolithic crystal filter comprising: a. a piezoelectric plate; b. a plurality of pairs of main electrodes arranged on said plate, first and second pairs of which are connected respectively to input and output terminals; and c. at least a pair of intermediate electrodes positioned on said plate between successive pairs of said main electrodes in a plane defined by said main electrodes, said intermediate electrodes being electrically distinct from said successive pairs of main electrodes; d. wherein the drop in frequency due to said intermediate electrode is largeR than the drop in frequency due to said main electrodes; e. all main electrodes being an energy trapping type electrode which generates a standing wave of mechanical oscillation therebeneath; f. and said intermediate electrode having a mass per unit area larger than said one main electrode, said intermediate electrode operating to couple energy of said standing wave with the next successive main electrode by inverting the phase of said standing wave by 180*.