An acoustic wave device is provided with a low-frequency side filter having a low-frequency side passband, a high-frequency side filter having a high-frequency side passband, and first and second balanced terminals. The low-frequency side filter is connected to a first unbalanced terminal. The low-frequency side passband is a frequency band from a first minimum frequency to a first maximum frequency. The high-frequency side filter is connected to a second unbalanced terminal. The high-frequency side passband is a frequency band from a second minimum frequency to a second maximum frequency. The low-frequency side filter includes a first longitudinally-coupled acoustic wave resonator and a first one-terminal pair acoustic wave resonator connected in series to the first longitudinally-coupled acoustic wave resonator. An antiresonant frequency of the first one-terminal pair acoustic wave resonator is set to be higher than the first maximum frequency and lower than the second minimum frequency.

The present invention relates to a surface acoustic wave filter device with floating units. The surface acoustic wave filter device comprises a piezoelectric substrate, at least one interdigitated transducer configuration and at least one floating unit. The interdigitated transducer configuration comprises a plurality of interdigitated transducer units disposed on the piezoelectric substrate. The floating unit is disposed between adjacent interdigitated transducer units, and covers partial region of adjacent interdigitated transducer units to reduce the BAW scattering of the surface acoustic wave filter device, and can be used to improve the amplitude and phase balances of the surface acoustic wave filter devices.

In a high-frequency module, a phase and amplitude of a high-frequency signal from a connection conductor between filter devices change due to the signal being transmitted by a takeout circuit unit. When the high-frequency signal at a third external connection terminal is a suppression signal and a high-frequency signal passing through the first filter circuit is a suppression-target signal, the transmission distance in the takeout circuit unit is such that the phase of the suppression signal is approximately inverted with respect to the phase of the suppression-target signal and the suppression signal has approximately the same amplitude as the suppression-target signal. The suppression signal is mixed with the suppression-target signal and components outside of the pass band are cancelled out and the attenuation characteristics of the filter circuit are enhanced.

A high frequency module includes a first external connection terminal, a second external connection terminal, a filter unit, a first matching circuit, and a second matching circuit. The filter unit is connected between the first external connection terminal and the second external connection terminal. The first matching circuit is connected between the first external connection terminal and the filter unit. The second matching circuit is connected between the second external connection terminal and the filter unit. The first matching circuit and the second matching circuit are inductively or capacitively coupled to each other.

In a filter device, first and second filter sections are connected in parallel between an input terminal and an output terminal. The first filter section is a longitudinally coupled resonator-type elastic wave filter including first and second inter-stage wiring lines with a two-stage cascading connection. The second filter section is a longitudinally coupled resonator-type elastic wave filter including third and fourth inter-stage wiring lines with a two-stage cascading connection. The phases of signals flowing in the third inter-stage wiring line and the second inter-stage wiring line are inverse. Terminal portions of an interdigital transducer electrode connected to the second inter-stage wiring line and an interdigital transducer electrode connected to the third inter-stage wiring line that are connected to a potential that is not a hot-side potential are connected by a virtual ground wiring line. A hot-side wiring portion that is adjacent to the virtual ground wiring line is disposed on an insulating film provided on the piezoelectric substrate.

In an elastic wave device, a plurality of elastic wave elements that include IDT electrodes are provided on a piezoelectric substrate, and a support layer that surrounds the elastic wave elements is provided on the piezoelectric substrate to define hollow portions in which the elastic wave elements are located. A cover member is stacked on the support layer, so that the hollow portions, in which the elastic wave elements are located, are provided, and the support layer includes a first support layer and a second support layer. The first support layer extends along an outer peripheral edge of the piezoelectric substrate, and the second support layer is located in a region surrounded by the first support layer and disposed around the elastic wave elements so as to have the hollow portions, in which the elastic wave elements are located. A hollow path is provided between the first support layer and the second support layer and arranged to allow communication between at least two of the hollow portions.

A high-frequency module includes a filter unit and first and second external connection terminals. The filter unit includes first and second terminals and a plurality of SAW resonators. The plurality of SAW resonators are connected to one another by connection conductors. A matching element is connected between the first terminal and the first external connection terminal, and a matching element is connected between the second terminal and the second external connection terminal. At least one of the matching elements is inductively coupled or capacitively coupled to at least one of the connection conductors located at a position such that at least one of the SAW resonators is interposed between the matching element and the connection conductor.

The present invention relates to a surface acoustic wave filter device with floating units. The surface acoustic wave filter device comprises a piezoelectric substrate, at least one interdigitated transducer configuration and at least one floating unit. The interdigitated transducer configuration comprises a plurality of interdigitated transducer units disposed on the piezoelectric substrate. The floating unit is disposed between adjacent interdigitated transducer units, and covers partial region of adjacent interdigitated transducer units to reduce the BAW scattering of the surface acoustic wave filter device, and can be used to improve the amplitude and phase balances of the surface acoustic wave filter devices.