A surface acoustic wave resonator device comprises a substrate supporting: a gateable, electrically conducting layer; an interdigital transducer (IDT); a reflector grating that comprises a plurality of electrically separated fingers; a main ohmic contact; and a gate element. The IDT is configured to be connectable to a ground. The conducting layer is configured to be connectable to the ground via the main ohmic contact, while each of said fingers is electrically connected to a lateral side of the conducting layer. This defines a gateable channel, which extends from the fingers to the ground via the conducting layer and the main ohmic contact. The gate element is electrically insulated from the conducting layer. The gate element is configured to allow an electrical impedance of the gateable channel to be continuously tuned by applying a voltage bias to this gate element with respect to the ground, in operation of the device.

An elastic wave includes a piezoelectric substrate having a polarization direction denoted by an arrow Px, and first and second IDT electrodes arranged on the substrate in an elastic wave propagation direction with a shared reflector therebetween. A first bus bar of the first IDT electrode and a first end portion bus bar of a second reflector are connected to a wiring electrode to define a first terminal. A second bus bar of the first IDT electrode and a second end portion bus bar of the shared reflector are connected to each other to define a second terminal. A first end portion bus bar and a first bus bar are electrically connected to each other. A second bus bar and a second end portion bus bar are electrically connected to each other, and the first and second IDT electrodes and are connected in parallel between the first and second terminals.

An elastic wave resonator includes a first, second and third reflectors. The first reflector is between a portion including a first IDT electrode and a third IDT electrode and a portion including a second IDT electrode and a fourth IDT electrode and is shared by the first to fourth IDT electrodes. The second reflector is shared by the first and third IDT electrodes. The third reflector is shared by the second and fourth IDT electrodes. The first and third IDT electrodes share a first common busbar. The second and fourth IDT electrodes share a second common busbar. The first and second common busbars are connected to the first reflector. A first busbar, a second busbar, a third busbar, and a fourth busbar of the respective first to fourth IDT electrodes are electrically connected to each other.

A surface acoustic wave resonator device comprises a substrate supporting: a gateable, electrically conducting layer; an interdigital transducer (IDT); a reflector grating that comprises a plurality of electrically separated fingers; a main ohmic contact; and a gate element. The IDT is configured to be connectable to a ground. The conducting layer is configured to be connectable to the ground via the main ohmic contact, while each of said fingers is electrically connected to a lateral side of the conducting layer. This defines a gateable channel, which extends from the fingers to the ground via the conducting layer and the main ohmic contact. The gate element is electrically insulated from the conducting layer. The gate element is configured to allow an electrical impedance of the gateable channel to be continuously tuned by applying a voltage bias to this gate element with respect to the ground, in operation of the device.

An elastic wave resonator includes a first, second and third reflectors. The first reflector is between a portion including a first IDT electrode and a third IDT electrode and a portion including a second IDT electrode and a fourth IDT electrode and is shared by the first to fourth IDT electrodes. The second reflector is shared by the first and third IDT electrodes. The third reflector is shared by the second and fourth IDT electrodes. The first and third IDT electrodes share a first common busbar. The second and fourth IDT electrodes share a second common busbar. The first and second common busbars are connected to the first reflector. A first busbar, a second busbar, a third busbar, and a fourth busbar of the respective first to fourth IDT electrodes are electrically connected to each other.

A surface acoustic wave resonator device comprises a substrate supporting: a gateable, electrically conducting layer; an interdigital transducer (IDT); a reflector grating that comprises a plurality of electrically separated fingers; a main ohmic contact; and a gate element. The IDT is configured to be connectable to a ground. The conducting layer is configured to be connectable to the ground via the main ohmic contact, while each of said fingers is electrically connected to a lateral side of the conducting layer. This defines a gateable channel, which extends from the fingers to the ground via the conducting layer and the main ohmic contact. The gate element is electrically insulated from the conducting layer. The gate element is configured to allow an electrical impedance of the gateable channel to be continuously tuned by applying a voltage bias to this gate element with respect to the ground, in operation of the device.

A surface acoustic wave resonator device comprises a substrate supporting: a gateable, electrically conducting layer; an interdigital transducer (IDT); a reflector grating that comprises a plurality of electrically separated fingers; a main ohmic contact; and a gate element. The IDT is configured to be connectable to a ground. The conducting layer is configured to be connectable to the ground via the main ohmic contact, while each of said fingers is electrically connected to a lateral side of the conducting layer. This defines a gateable channel, which extends from the fingers to the ground via the conducting layer and the main ohmic contact. The gate element is electrically insulated from the conducting layer. The gate element is configured to allow an electrical impedance of the gateable channel to be continuously tuned by applying a voltage bias to this gate element with respect to the ground, in operation of the device.