Patent ID: 11870408
Assignee: VTT TECHNICAL RESEARCH CENTRE OF FINLAND LTD
Field: Basic communication processes (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. An acoustic wave filter device comprising:
a first electrode comprising a first input electrode and a first output electrode;
a second electrode comprising a second input electrode and a second output electrode, the second input electrode being electrically connected to the first output electrode;
a piezoelectric layer beneath the first electrode and the second electrode;
a counter electrode beneath the piezoelectric layer;
an intermediary layer beneath the counter electrode, the intermediary layer comprising a first region and a second region, the first region having a first layer thickness and the second region having a second layer thickness different from the first layer thickness; and
wherein the first electrode is located over the first region of the intermediary layer, and the second electrode is located over the second region of the intermediary layer, and
wherein the acoustic wave filter device is configured such that application of a radio frequency voltage between the first input electrode and the counter electrode creates acoustic resonance modes in the piezoelectric layer to create (i) a first passband peak in a first transmission curve formed for transmissions between the first input and output electrodes, (ii) a second passband peak in a second transmission curve formed for transmissions between the second input and output electrodes, (iii) a first sideband peak in the first transmission curve, and (iv) a second sideband peak in the second transmission curve, and wherein a frequency difference between the first passband peak and the second passband peak is less than a frequency difference between the first sideband peak and the second sideband peak.