Abstract: An acoustic wave filter includes input and output terminals, and series arm and parallel arm circuits. The series arm circuit includes first and second series arm resonators connected in series between the input and output terminals. The parallel arm circuit includes a parallel arm resonator connected between the series arm circuit and a ground potential. Each of the first and second series arm resonators is a SAW resonator including a piezoelectric substrate and an IDT electrode on the piezoelectric substrate, and has a characteristic that a fractional band width increases with a decrease in a thickness of the piezoelectric substrate. An anti-resonant frequency of the first series arm resonator is lower than an anti-resonant frequency of the second series arm resonator. A wavelength of a signal passing through the first series arm resonator is shorter than a wavelength of a signal passing through the second series arm resonator.

Abstract: A filter includes a signal path connecting an input terminal and an output terminal one or more series arm circuits on the signal path, and one or more parallel arm circuits connected to one or more nodes disposed on the signal path and a ground electrode. The one or more series arm circuits define any of a section between nodes adjacent to each other, a section between a node closest to the input terminal and the input terminal, and a section between a node closest to the output terminal and the output terminal. Among the one or more series arm circuits and the one or more parallel arm circuits, one circuit does not include any acoustic wave resonator, and another circuit includes an acoustic wave resonator.

Abstract: A multiplexer includes a first filter on a first path, a second filter on a second path, and a third filter on a third path. A frequency of intermodulation distortion generated by a transmission signal within a pass band of the first filter and a transmission signal within a pass band of the second filter is within a pass band of the third filter. The first filter includes one or more series resonators on the first path and one or more parallel resonators on one or more paths connecting one or more nodes on the first path to a ground. A relative permittivity of a resonator of the one or more series resonators and the one or more parallel resonators that is closest to a common terminal is lowest among relative permittivities of the resonators.

Abstract: A filter includes a signal path connecting an input terminal and an output terminal one or more series arm circuits on the signal path, and one or more parallel arm circuits connected to one or more nodes disposed on the signal path and a ground electrode. The one or more series arm circuits define any of a section between nodes adjacent to each other, a section between a node closest to the input terminal and the input terminal, and a section between a node closest to the output terminal and the output terminal. Among the one or more series arm circuits and the one or more parallel arm circuits, one circuit does not include any acoustic wave resonator, and another circuit includes an acoustic wave resonator.

Abstract: To improve characteristics of a semiconductor device (semiconductor laser), an active layer waveguide (AWG) comprised of InP is formed over an exposed part of a surface of a substrate having an off angle ranging from 0.5° to 1.0° in a [1-1-1] direction from a (100) plane to extend in the [0-1-1] direction. A cover layer comprised of p-type InP is formed over the AWG with a V/III ratio of 2000 or more. Thereby, it is possible to obtain excellent multiple quantum wells (MQWs) by reducing a film thickness variation of the AWG. Moreover, the cover layer having side faces where a (0-11) plane almost perpendicular to a substrate surface mainly appears can be formed. A sectional shape of a lamination part of the cover layer and the AWG becomes an approximately rectangular shape. Therefore, an electrification region can be enlarged and it is possible to reduce a resistance of the semiconductor device.

Abstract: A radio-frequency front-end circuit includes a first filter that has a first pass band and is connected to an antenna common terminal, a second filter that has a second pass band and is connected to the antenna common terminal, a switch that includes a common terminal and selection terminals, the common terminal being connected to the first filter, and a third filter that is connected to one of the selection terminals and is disposed between the switch and an input/output terminal. A reflection coefficient of the first filter alone in the second pass band viewed from the antenna common terminal is larger than a reflection coefficient of the third filter alone in the second pass band viewed from the antenna common terminal.

Abstract: In a semiconductor laser, a block layer is provided on both sides of a mesa-type semiconductor part having an n-type cladding layer, an active layer, and a p-type cladding layer. The block layer has: a p-type block layer formed on the side surface of the mesa-type semiconductor part and over a p-type semiconductor substrate; a high-resistance layer formed over the p-type block layer; and an n-type block layer formed over the high-resistance layer, which has a higher resistance than that of the p-type block layer. By providing the high-resistance layer between the p-type block layer and the n-type block layer, the thickness of the p-type block layer can be controlled and a leakage current (flow of a hole) can be reduced. Further, the distance between the n-type cladding layer and the n-type block layer can be secured, and hence a leakage current (flow of an electron) can be prevented.

Abstract: In a filter device, a first filter and a second filter are connected to a common connection point by a filter connection conductor line including a first conductor line portion, and a parallel connection area with an electrical length shorter than that in a single conductor line is provided in the first conductor line portion.

Abstract: A radio-frequency front-end circuit includes a first filter that has a first pass band and is connected to an antenna common terminal, a second filter that has a second pass band and is connected to the antenna common terminal, a switch that includes a common terminal and selection terminals, the common terminal being connected to the first filter, and a third filter that is connected to one of the selection terminals and is disposed between the switch and an input/output terminal. A reflection coefficient of the first filter alone in the second pass band viewed from the antenna common terminal is larger than a reflection coefficient of the third filter alone in the second pass band viewed from the antenna common terminal.

Abstract: A multiplexer includes filters connected to each other at a common terminal, a low-frequency filter with a first pass band, and a high-frequency filter with a second pass band that is higher than the first pass band. The low-frequency filter includes an initial-stage filter section including at least one first elastic wave resonator located on the common terminal side among at least two elastic wave resonators, and a subsequent-stage filter section that includes a second elastic wave resonator other than the at least one first elastic wave resonator. A reflection coefficient in the second pass band when the initial-stage filter section is viewed from the common terminal side as a single component is larger than a reflection coefficient in the second pass band when the subsequent-stage filter section is viewed from the common terminal side as a single component.

Abstract: A multiplexer includes filters connected to each other at a common terminal, a low-frequency filter with a first pass band, and a high-frequency filter with a second pass band that is higher than the first pass band. The low-frequency filter includes an initial-stage filter section including at least one first elastic wave resonator located on the common terminal side among at least two elastic wave resonators, and a subsequent-stage filter section that includes a second elastic wave resonator other than the at least one first elastic wave resonator. A reflection coefficient in the second pass band when the initial-stage filter section is viewed from the common terminal side as a single component is larger than a reflection coefficient in the second pass band when the subsequent-stage filter section is viewed from the common terminal side as a single component.

Abstract: To improve characteristics of a semiconductor device (semiconductor laser), an active layer waveguide (AWG) comprised of InP is formed over an exposed part of a surface of a substrate having an off angle ranging from 0.5° to 1.0° in a [1-1-1] direction from a (100) plane to extend in the [0-1-1] direction. A cover layer comprised of p-type InP is formed over the AWG with a V/III ratio of 2000 or more. Thereby, it is possible to obtain excellent multiple quantum wells (MQWs) by reducing a film thickness variation of the AWG. Moreover, the cover layer having side faces where a (0-11) plane almost perpendicular to a substrate surface mainly appears can be formed. A sectional shape of a lamination part of the cover layer and the AWG becomes an approximately rectangular shape. Therefore, an electrification region can be enlarged and it is possible to reduce a resistance of the semiconductor device.

Abstract: To improve characteristics of a semiconductor device (semiconductor laser), an active layer waveguide (AWG) comprised of InP is formed over an exposed part of a surface of a substrate having an off angle ranging from 0.5° to 1.0° in a [1-1-1] direction from a (100) plane to extend in the [0-1-1] direction. A cover layer comprised of p-type InP is formed over the AWG with a V/III ratio of 2000 or more. Thereby, it is possible to obtain excellent multiple quantum wells (MQWs) by reducing a film thickness variation of the AWG. Moreover, the cover layer having side faces where a (0-11) plane almost perpendicular to a substrate surface mainly appears can be formed. A sectional shape of a lamination part of the cover layer and the AWG becomes an approximately rectangular shape. Therefore, an electrification region can be enlarged and it is possible to reduce a resistance of the semiconductor device.

Abstract: A filter device with a ladder circuit configuration includes series arm resonators and parallel arm resonators, a filter component mounted on a mounting substrate and including a chip substrate and an elastic wave filter chip, a circuit configuration in which a plurality of series arm resonators and parallel arm resonators are defined by the elastic wave filter chip, and inductances are connected between ground-potential-side end portions of the plurality of parallel arm resonators and a ground potential, and in which at least one of the plurality of inductances is provided in the chip substrate and a remaining at least one inductance is provided in the mounting substrate.

Abstract: In a filter device, a first filter and a second filter are connected to a common connection point by a filter connection conductor line including a first conductor line portion, and a parallel connection area with an electrical length shorter than that in a single conductor line is provided in the first conductor line portion.

Abstract: A filter device includes a first signal terminal, a second signal terminal, a filter unit, a first inductor and a second inductor. The filter unit is connected between the first signal terminal and the second signal terminal. The first inductor is connected between a connection point between the filter unit and the first signal terminal, and a ground potential. The second inductor is connected between the filter unit and the second signal terminal. The second inductor is electromagnetically coupled with the first inductor.

Abstract: In a semiconductor laser, a block layer is provided on both sides of a mesa-type semiconductor part having an n-type cladding layer, an active layer, and a p-type cladding layer. The block layer has: a p-type block layer formed on the side surface of the mesa-type semiconductor part and over a p-type semiconductor substrate; a high-resistance layer formed over the p-type block layer; and an n-type block layer formed over the high-resistance layer, which has a higher resistance than that of the p-type block layer. By providing the high-resistance layer between the p-type block layer and the n-type block layer, the thickness of the p-type block layer can be controlled and a leakage current (flow of a hole) can be reduced. Further, the distance between the n-type cladding layer and the n-type block layer can be secured, and hence a leakage current (flow of an electron) can be prevented.

Abstract: A ladder filter device includes elastic wave resonators with IDT electrodes. An apodization angle ? in an IDT electrode of a series arm resonator in the ladder filter device falls within a range from about 2° to about 14° with respect to an elastic wave propagation direction. This arrangement provides a ladder filter device that has a smaller insertion loss in a low frequency side portion of a passing band.

Abstract: A filter device with a ladder circuit configuration includes series arm resonators and parallel arm resonators, a filter component mounted on a mounting substrate and including a chip substrate and an elastic wave filter chip, a circuit configuration in which a plurality of series arm resonators and parallel arm resonators are defined by the elastic wave filter chip, and inductances are connected between ground-potential-side end portions of the plurality of parallel arm resonators and a ground potential, and in which at least one of the plurality of inductances is provided in the chip substrate and a remaining at least one inductance is provided in the mounting substrate.

Abstract: A filter device includes a first signal terminal, a second signal terminal, a filter unit, a first inductor and a second inductor. The filter unit is connected between the first signal terminal and the second signal terminal. The first inductor is connected between a connection point between the filter unit and the first signal terminal, and a ground potential. The second inductor is connected between the filter unit and the second signal terminal. The second inductor is electromagnetically coupled with the first inductor.