The present disclosure relates to a ladder-type surface acoustic wave (SAW) device, which includes a piezoelectric layer, two reflective structures, at least one series interdigital transducer (IDT) coupled between a first signal point and a second signal point, and at least one shunt IDT. The at least one shunt IDT is coupled at least between the first signal point and ground, or between the second signal point and ground. Herein, the two reflective structures, the at least one series IDT, and the at least one shunt IDT reside over the piezoelectric layer. The at least one series IDT and the at least one shunt IDT are arranged between the two reflective structures.

The present disclosure relates to a ladder-type surface acoustic wave (SAW) device, which includes a piezoelectric layer, two reflective structures, at least one series interdigital transducer (IDT) coupled between a first signal point and a second signal point, and at least one shunt IDT. The at least one shunt IDT is coupled at least between the first signal point and ground, or between the second signal point and ground. Herein, the two reflective structures, the at least one series IDT, and the at least one shunt IDT reside over the piezoelectric layer. The at least one series IDT and the at least one shunt IDT are arranged between the two reflective structures.

Aspects of the disclosure relate to an electroacoustic device that includes a piezoelectric material and an electrode structure. The electrode structure includes a first busbar and a second busbar. The electrode structure further includes electrode fingers arranged in an interdigitated manner and including a first plurality of fingers connected to the first busbar and a second plurality of fingers connected to the second busbar. A first distance between the first busbar and the second plurality of fingers and a second distance between the second busbar and the first plurality of fingers both being less than a pitch of the electrode fingers. The electrode fingers have a central region with a first trap region and a second trap region respectively located on boundaries of the central region. A structural characteristic of the electroacoustic device is different in the first trap region and the second trap region relative to the central region.

Aspects of the disclosure relate to an electroacoustic device that includes a piezoelectric material and an electrode structure. The electrode structure includes a first busbar and a second busbar. The electrode structure further includes a first conductive structure connected to the first busbar and a second conductive structure connected to the second busbar. The first conductive structure and the second conductive structure is disposed between the first busbar and the second busbar. The first conductive structure and the second conductive structure each include a plurality of conductive segments separated from each other and extending towards one of the first busbar or the second busbar. The electrode structure further includes electrode fingers arranged in an interdigitated manner and each connected to either the first conductive structure or the second conductive structure. The electrode fingers have a pitch that is different than a pitch of the plurality of conductive segments.

A bandpass acoustic wave filter device includes an IDT electrode and a dielectric film disposed on a piezoelectric substrate including a LiNbO.sub.3 layer, and an acoustic wave resonator is defined by the IDT electrode. The acoustic wave resonator utilizes the Rayleigh wave, and a response of an SH wave excited by the acoustic wave resonator is outside a pass band of the acoustic wave filter device.

A filter device includes a first path, a second path, and a capacitor. The first path includes at least one ladder filter circuit and connects a first terminal and a second terminal. The at least one ladder filter circuit includes a parallel arm resonator connected to a ground terminal. The second path includes a grounded resonator and is connected in parallel with any of the at least one ladder filter circuit. One end of the capacitor is connected to the second path, and the other end of the capacitor is connected to a third path which connects the parallel arm resonator and the ground terminal.

An apparatus is disclosed for a reconfigurable filter. In example aspects, the apparatus includes a filter circuit that has a first filter port and a second filter port. The filter circuit includes a filter network, an acoustic resonator, and a switch circuit. The filter network includes one or more acoustic resonators coupled between the first filter port and the second filter port. The acoustic resonator is coupled to the filter network and coupled between the first filter port and the second filter port. The switch circuit is coupled between the acoustic resonator and the second filter port, and the switch circuit is configured to connect the acoustic resonator into a parallel acoustic resonator arrangement in a first state and connect the acoustic resonator into a serial acoustic resonator arrangement in a second state.

Filters 10 and 20 having respective pass bands different from each other, a common terminal to which a terminal 11 of the filter 10 and a terminal of the filter 20 are connected, and an inductor of which one end is connected to the terminal 11 and another end is connected to the common terminal. The filter 10 includes a longitudinally coupled resonator formed of a resonator 132 and resonators 131 and 133 disposed on both sides of the resonator 132, in which the resonator 132 is connected to the terminal 11, and a parallel resonator of which one end is connected to the resonator 132 and another end is connected to a ground electrode, and the resonator 132 and the parallel resonator of the resonators included in the filter 10 are connected to a signal path between the resonator 132 and the terminal 11.

Acoustic wave devices and interdigital transducer (IDT) arrangements for surface acoustic wave (SAW) devices are disclosed. Representative SAW devices are described herein that provide sharp transitions between passband frequencies and frequencies that are outside of desired passbands. A SAW device may include several IDTs arranged between reflective structures on a piezoelectric material and one or more additional IDTs or electrode pairs that are configured to modify the influence of parasitic capacitance, or other internal device capacitance, thereby improving steepness on the upper side of a passband as well as improving rejection for frequencies outside of the passband. The one or more additional IDTs or electrode pairs may be configured as at least one of a capacitor, an IDT capacitor, an IDT with a floating electrode, or combinations thereof.

Multi-mode surface acoustic wave filters are disclosed. A multi-mode surface acoustic wave filter can include a plurality of interdigital transducer electrodes that are longitudinally coupled to each other and stepped acoustic reflectors on opposing sides of the plurality of interdigital transducer electrodes. The acoustic reflectors include acoustic reflector fingers with stepped lengths.