Systems, methods, and devices for reducing insertion loss and/or swapping transmitter (TX) and receiver (RX) frequencies in an electrical balance duplexer (EBD) used in a transceiver device for frequency division duplexing (FDD) applications are provided. Feed-forward receiver path from the antenna to a low noise amplifier (LNA) and a feed-forward path from the antenna to a power amplifier (PA) of the EBD may be used for reducing insertion loss of the RX and TX signals. In some embodiments, switches may be used to selectively alter operational modes for varied levels of isolation and/or swapping of TX and RX frequencies.

An elastic wave device includes a supporting substrate, an acoustic reflection layer disposed on the supporting substrate, a piezoelectric layer disposed on the acoustic reflection layer, and an interdigital transducer electrode disposed on the piezoelectric layer. The acoustic reflection layer includes three or more low acoustic impedance layers and two or more high acoustic impedance layers. A film thickness of the low acoustic impedance layer closest to the piezoelectric layer is larger than a film thickness of the low acoustic impedance layer closest to the low acoustic impedance layer that is closest to the piezoelectric layer.

A SAW filter with an antenna and a transmission terminal includes: a plurality of series resonator groups which are connected in series between the antenna and the transmission terminal; a plurality of parallel resonator groups which are connected in parallel between two neighbor series resonator groups among the plurality of series resonator groups; a parallel inductor which is connected in parallel with the series resonator group adjacent to the antenna; and a series inductor which is connected to in series with some parallel resonator groups among the plurality of parallel resonator groups. The SAW filter has high durability in which even though high power is applied to the filter together with the wide pass band, the filter is not damaged.

A multiplexer includes a transmission-side filter electrically connected to a common terminal and a transmission input terminal, and a transmission-side filter electrically connected to the common terminal and a transmission input terminal. The transmission-side filter includes a plurality of series arm resonators and a plurality of parallel arm resonators. Capacitance elements are respectively electrically connected in parallel to the series arm resonator and the parallel arm resonator, which are connected most proximately to the common terminal. IDT electrodes of a series arm resonator and a parallel arm resonator connected most proximately to the common terminal do not include a thinning electrode, and others of the series arm resonators and the parallel arm resonators include thinning electrodes.

A method of manufacturing an acoustic wave device is disclosed. The method includes attaching a support layer to a ceramic layer. The support layer has a higher thermal conductivity than the ceramic layer. The ceramic layer can be a polycrystalline spinel layer. The method also includes bonding a piezoelectric layer to a surface of the ceramic layer. The method further includes forming an interdigital transducer electrode over the piezoelectric layer.

An acoustic wave device is disclosed. The acoustic wave device includes a support layer, a ceramic layer positioned over the support layer, a piezoelectric layer positioned over the ceramic layer, and an interdigital transducer electrode positioned over the piezoelectric layer. The support layer has a higher thermal conductivity than the ceramic layer. The ceramic layer can be a polycrystalline spinel layer. The acoustic wave device can be a surface acoustic wave device configured to generate a surface acoustic wave.

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 device is disclosed. The acoustic wave device includes a piezoelectric layer, an interdigital transducer electrode positioned over the piezoelectric layer, and an anti-refection layer over a conductive layer of the interdigital transducer electrode. The conductive layer can include aluminum, for example. The anti-reflection layer can include silicon. The anti-reflection layer can be free from a material of the interdigital transducer electrode. The acoustic wave device can further include a temperature compensation layer positioned over the anti-reflection layer in certain embodiments.

An antenna terminal is connected to a first filter and second filter, which are branched from each other when viewed from the antenna terminal, and are different in passing bands from each other. An individual inductor is connected in series to a branch point from which the first filter is branched to be independent from other filters when viewed from the antenna terminal. And a common inductor is located between a position between the antenna terminal and the branch point and a reference potential and is commonly connected in parallel with respect to the filters. The first filter is higher in frequency of passing band compared with the other filters. A susceptance when viewing the second filter side from the antenna terminal is larger than a susceptance when viewing the first filter side from the antenna terminal at frequencies of passing bands of them.

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.