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.

Radio frequency (RF) filtering devices, and particularly compensation structures for RF filtering devices are disclosed. Representative RF filtering devices are described that include compensation structures configured to adjust, reduce, or cancel leakage signals within the RF filtering devices, thereby providing improved isolation. Compensation structures may include surface acoustic wave (SAW) devices having multiple interdigital transducers (IDT) that are longitudinally coupled between two reflective structures. Different IDTs of a SAW device may be electrically connected to an RF filtering device, and at least one IDT of the SAW device may comprise an electrically floating electrode that provides the ability to further tune acoustic waves. Depending on the application, the compensation structure may be electrically connected to different portions of the RF filtering device. In certain embodiments, the RF filtering device is an RF duplexing device.

An integrated module of acoustic wave device with active thermal compensation comprises a substrate, an acoustic wave filter, an active adjustment circuit and at least one variable capacitance device. The acoustic wave filter comprises a plurality of series acoustic wave resonators formed on the substrate, at least one shunt acoustic wave resonator formed on the substrate and a thermal sensing acoustic wave resonator. Each of the variable capacitance device is connected in parallel to one of the series and shunt acoustic wave resonators. The active adjustment circuit outputs an active thermal compensation signal correlated to a thermal variation sensed by the thermal sensing acoustic wave resonator to the variable capacitance device. The active thermal compensation signal induces a capacitance variation of the variable capacitance device such that the impact of the thermal variation to the acoustic wave device is compensated.

An acoustic wave filter having thermal sensing acoustic wave resonator comprises a substrate, a plurality of series acoustic wave resonators formed on the substrate, at least one shunt acoustic wave resonator formed on the substrate and a thermal sensing acoustic wave resonator. The thermal sensing acoustic wave resonator is one of a series acoustic wave resonator and a shunt acoustic wave resonator. Thereby the thermal sensing acoustic wave resonator plays dual roles of thermal sensing and acoustic wave filtering.

Radio frequency (RF) filtering devices, and particularly compensation structures for RF filtering devices are disclosed. Representative RF filtering devices are described that include compensation structures configured to adjust, reduce, or cancel leakage signals within the RF filtering devices, thereby providing improved isolation. Compensation structures may include surface acoustic wave (SAW) devices having multiple interdigital transducers (IDT) that are longitudinally coupled between two reflective structures. Different IDTs of a SAW device may be electrically connected to an RF filtering device, and at least one IDT of the SAW device may comprise an electrically floating electrode that provides the ability to further tune acoustic waves. Depending on the application, the compensation structure may be electrically connected to different portions of the RF filtering device. In certain embodiments, the RF filtering device is an RF duplexing device.

A thermal sensor circuit comprises a conversion circuit which is one of a buck DC-DC converter circuit and a boost DC-DC converter circuit, wherein the conversion circuit comprises an inductor and an output terminal. A thermal sensor senses a thermal variation correlated to a capacitance variation of the thermal sensor. The capacitance variation induces an internal parasitic capacitance variation of the inductor which is connected in parallel to the thermal sensor and results a variation of an energy stored in the inductor. Hence a variation of a converted circuit signal outputting by the output terminal is caused, wherein the variation of the converted circuit signal is correlated to the thermal variation.

A branching 1 filter has an antenna terminal 3 which receives signal waves and disturbance waves, a transmission filter 11 which is connected to the antenna terminal 3, a reception filter 13 which is connected to the antenna terminal 3 and receives a portion of the signal waves and has, as a passband, a frequency range higher than a passband of the transmission filter 11, and a disturbance wave resonator which is connected to the antenna terminal 3 and to the ground and positioned closer to the antenna terminal 3 side than the transmission filter 11 and the reception filter 13. The disturbance wave resonator 15 is connected to antenna terminal 3 at a position closer to the antenna terminal 3 side than the transmission filter 11 and the reception filter 13. A resonance frequency of the disturbance wave resonator 15 is within a frequency range smaller than the passband of the transmission filter and includes a frequency range of the disturbance waves.

An acoustic wave filter having thermal sensing acoustic wave resonator comprises a substrate, a plurality of series acoustic wave resonators formed on the substrate, at least one shunt acoustic wave resonator formed on the substrate and a thermal sensing acoustic wave resonator. The thermal sensing acoustic wave resonator is one of a series acoustic wave resonator and a shunt acoustic wave resonator. Thereby the thermal sensing acoustic wave resonator plays dual roles of thermal sensing and acoustic wave filtering.

A thermal sensor circuit comprises a conversion circuit which is one of a buck DC-DC converter circuit and a boost DC-DC converter circuit, wherein the conversion circuit comprises an inductor and an output terminal. A thermal sensor senses a thermal variation correlated to a capacitance variation of the thermal sensor. The capacitance variation induces an internal parasitic capacitance variation of the inductor which is connected in parallel to the thermal sensor and results a variation of an energy stored in the inductor. Hence a variation of a converted circuit signal outputting by the output terminal is caused, wherein the variation of the converted circuit signal is correlated to the thermal variation.

An integrated module of acoustic wave device with active thermal compensation comprises a substrate, an acoustic wave filter, an active adjustment circuit and at least one variable capacitance device. The acoustic wave filter comprises a plurality of series acoustic wave resonators formed on the substrate, at least one shunt acoustic wave resonator formed on the substrate and a thermal sensing acoustic wave resonator. Each of the variable capacitance device is connected in parallel to one of the series and shunt acoustic wave resonators. The active adjustment circuit outputs an active thermal compensation signal correlated to a thermal variation sensed by the thermal sensing acoustic wave resonator to the variable capacitance device. The active thermal compensation signal induces a capacitance variation of the variable capacitance device such that the impact of the thermal variation to the acoustic wave device is compensated.