Abstract: An energy trapping type piezoelectric filter comprising a first piezoelectric substrate (1A) and a second piezoelectric substrate (1B) having an identical configuration and arranged in layers with an adhesive sheet or spacer (20A) interposed therebetween and insulating top and base plates (30A, 30B) arranged on and under the respective piezoelectric substrates with adhesive sheets or spacers (20B, 20C) also interposed therebetween, wherein a shielding conductive member (40) is provided on an upper surface of the insulating base plate (30B) for preventing an electromagnetic coupling between an input electrode (31) and output electrodes (32A, 32B), the shielding conductive member (40) being connected to grounding electrodes (33A, 33B).

Abstract: An energy trapping type piezoelectric filter having a minimal surface area comprises a first and second identical piezoelectric substrates 10a and 10b being laid one on the other to form a multilayer structure, each having a first surface provided with a pair of oscillatory electrodes 11 and 12 arranged vis-a-vis relative to each other and a capacitor electrode 14 which is connected to one of the oscillatory electrodes 12, the other oscillatory electrode 11 being electrically connected to an input/output connection terminal 13 also arranged on the first surface, and a second surface provided with a common electrode 16 arranged oppositely relative to said pair of oscillatory electrodes 11 and 12 and a capacitor electrode 17 arranged opposite to said capacitor electrode 14, the capacitor electrode 17 and the common electrode 16 being electrically connected to each other, the pair of oscillatory electrodes 11 and 12 and the common electrode 16 forming an oscillating section V, the capacitor electrodes 14 and 17