Abstract: A radio frequency module includes a module board including a first principal surface and a second principal surface on opposite sides thereof, a transmission power amplifier, a control circuit that controls the transmission power amplifier, and a first inductor connected to an output terminal of the transmission power amplifier. The control circuit is disposed on the first principal surface, and the first inductor is disposed on the second principal surface.

Abstract: A radio frequency module includes a mounting board, a power amplifier, a plurality of transmission filters, a first switch, an output matching circuit, a low-noise amplifier, and an external-connection terminal. The mounting board includes a first principal surface and a second principal surface on opposite sides of the mounting board. The first switch switches a connection between the power amplifier and the transmission filters. The output matching circuit is connected between the power amplifier and the first switch. The low-noise amplifier is disposed on the second principal surface of the mounting board. The external-connection terminal is disposed on the second principal surface of the mounting board. The power amplifier, the output matching circuit, the first switch, and the transmission filters are disposed on the mounting board in stated order in a direction that is orthogonal to a thickness direction of the mounting board.

Abstract: A radio frequency module includes a module board including a first principal surface and a second principal surface on opposite sides of the module board, a transmission power amplifier connected to a transmission path, a first circuit component connected to a reception path, and a control circuit that controls the transmission power amplifier. The control circuit is disposed on the first principal surface, and the first circuit component is disposed on the second principal surface.

Abstract: A radio frequency module includes: a module board including a first principal surface and a second principal surface on opposite sides of the module board; an antenna connection terminal; a diplexer connected to the antenna connection terminal and including at least a first inductor which is a chip inductor; a transmission power amplifier; and a first circuit component disposed on a transmission path connecting the diplexer and the transmission power amplifier. The first inductor is disposed on the first principal surface, and one of the transmission power amplifier and the first circuit component is disposed on the second principal surface.

Abstract: There is provided a radio-frequency module that can reduce communication signal loss in both the case of employing one communication band of multiple communication bands and the case of employing two or more communication bands together. A radio-frequency module includes a first switching circuit and matching circuits. The matching circuits are provided individually for a first transmission path, a second transmission path, and a third transmission path. When communications are performed by using only a first communication band, the first switching circuit selects the first transmission path. When communications are performed by using together the first communication band and the second communication band, the first switching circuit selects the second transmission path and the third transmission path.

Abstract: A high-frequency module includes: a power receiving terminal; an LNA, a reception switch that switches among a plurality of signals in different bands and outputs the signals to the LNA; a first conduction path spanning from the power receiving terminal to a power source terminal of the reception switch; a second conduction path spanning from a branching point in the first conduction path to a power source terminal of the LNA; a third conduction path branching from at least one of the first conduction path and the second conduction path and spanning to a ground; and a capacitor inserted into the third conduction path. A second inductance of the second conduction path is greater than a first inductance of a part spanning from the branching point in the first conduction path to the power source terminal.

Abstract: A high-frequency module includes: a power receiving terminal; an LNA, a reception switch that switches among a plurality of signals in different bands and outputs the signals to the LNA; a first conduction path spanning from the power receiving terminal to a power source terminal of the reception switch; a second conduction path spanning from a branching point in the first conduction path to a power source terminal of the LNA; a third conduction path branching from at least one of the first conduction path and the second conduction path and spanning to a ground; and a capacitor inserted into the third conduction path. A second inductance of the second conduction path is greater than a first inductance of a part spanning from the branching point in the first conduction path to the power source terminal.

Abstract: A surface acoustic wave apparatus includes a piezoelectric substrate mounting a surface acoustic wave filter having a plurality of comb-like electrode sections, and another surface acoustic wave filter also having a plurality of comb-like electrode sections, in a manner such that a balun function is obtained. Further, a wiring pattern is provided on the piezoelectric substrate for a connecting reference terminal side electrode of a comb-like electrode section with a reference terminal side electrode of another comb-like electrode section. Moreover, another wiring pattern is provided on the piezoelectric substrate for connecting a reference terminal side electrode of a further comb-like electrode section with a reference terminal side electrode of a still further comb-like electrode section.

Abstract: A longitudinally coupled resonator type surface acoustic wave filter having a balance-unbalance conversion function achieves improved amplitude balance and phase balance. The surface acoustic wave filter includes first, second and third IDTs. The second IDT is positioned in the center of the three IDTs and has an even number of electrode fingers. The polarity of the electrode finger of the first IDT adjacent to the second IDT is opposite to the polarity of the electrode finger of the third IDT adjacent to the second IDT.

Abstract: A surface acoustic wave device includes at least four surface acoustic wave elements that are arranged to have an unbalanced-to-balanced conversion function. In a surface acoustic wave element on the balanced side, the phase between the input and output terminals is 180 degrees shifted so that the phase difference between the outputs on the balanced side becomes substantially 180 degrees.

Abstract: A surface acoustic wave filter apparatus includes extensional-coupling-resonator-mode first through fourth SAW filter devices which are disposed on a piezoelectric substrate. Each SAW filter device includes three interdigital transducers (IDTs) arranged in a SAW propagating direction, and reflectors arranged such that they sandwich the IDTs therebetween. The SAW filter devices have a balanced-to-unbalanced input/output function. The reflectors of the first and second SAW filter devices are different from those of the third and fourth SAW filter devices in at least one of the number, the pitch, the duty, and the thickness of the electrode fingers of the reflectors.

Abstract: A surface acoustic wave (SAW) device includes at least one longitudinally coupled resonator SAW filter and at least one SAW resonator connected in series to the SAW filter on a piezoelectric substrate. The SAW resonator is arranged such that the resonant frequency is located within the pass band of the SAW filter and the antiresonant frequency is located outside the pass band of the SAW filter. A dummy electrode is provided between an electrode finger and a bus bar of an interdigital transducer (IDT) of the SAW resonator. The gap between the dummy electrode and the electrode finger of the IDT is about 0.5&lgr; or less when the wavelength determined by the pitch between the electrode fingers of the interdigital transducers of the SAW resonator is indicated by &lgr;.

Abstract: A surface acoustic wave apparatus includes three longitudinally-coupled-resonator-type interdigital transducers (IDTs) having a balanced-to-unbalanced conversion function, which are provided on a piezoelectric substrate in a direction in which a surface acoustic wave (SAW) propagates. Weighting is applied to at least one of the IDTs. For example, among the electrode fingers of the IDT located on the left side, an apodization-weighted electrode finger is provided for one of the electrode fingers positioned adjacent to the central IDT.

Abstract: A longitudinally coupled resonator type surface acoustic wave filter having a balance-unbalance conversion function achieves improved amplitude balance and phase balance. The surface acoustic wave filter includes first, second and third IDTs. The second IDT is positioned in the center of the three IDTs and has an even number of electrode fingers. The polarity of the electrode finger of the first IDT adjacent to the second IDT is opposite to the polarity of the electrode finger of the third IDT adjacent to the second IDT.

Abstract: A longitudinally coupled resonator type surface acoustic wave filter having a balance-unbalance conversion function achieves improved amplitude balance and phase balance. The surface acoustic wave filter includes first, second and third IDTs. The second IDT is positioned in the center of the three IDTs and has an even number of electrode fingers. The polarity of the electrode finger of the first IDT adjacent to the second IDT is opposite to the polarity of the electrode finger of the third IDT adjacent to the second IDT.

Abstract: A surface acoustic wave filter device includes a piezoelectric substrate, and first and second surface acoustic wave filter elements disposed on the piezoelectric substrate. Each of the surface acoustic wave filters has a plurality of IDTs disposed along the surface acoustic wave propagation direction. The first and second surface acoustic wave filter elements are arranged such that they are substantially equal in transmission amplitude characteristic within a band but different in transmission phase characteristic by about 180°. One end of each of the first and second surface acoustic wave filter elements define an unbalanced terminal, and the other end of each of the first and second surface acoustic wave filter elements define a balanced terminal.

Abstract: A surface acoustic wave filter device, having a balanced-to-unbalanced conversion function, in which input/output impedances are different and in which the in-band degree of balance is satisfactory, is obtained. The surface acoustic wave filter device has a balanced-to-unbalanced conversion function, in which the spacing of input/output IDTs of a second surface acoustic wave filter element is larger by approximately half the wavelength of the surface-acoustic wave than that of a first surface acoustic wave filter element so that the phase is inverted, wherein the total of the electrostatic capacitance values of a plurality of IDTs of the second surface acoustic wave filter element is larger than the total of the electrostatic capacitance values of a plurality of IDTs of the first surface acoustic wave filter element.

Abstract: A surface acoustic wave filter device includes a piezoelectric substrate, and first, second and third surface acoustic wave filter elements disposed on the piezoelectric substrate. Each of the surface acoustic wave filters has a plurality of IDTs disposed along the surface acoustic wave propagation direction. The second and third surface acoustic wave filter elements are arranged such that they are substantially equal in transmission amplitude characteristic within a band but different in transmission phase characteristic by about 180°. At least one IDT of the second surface acoustic wave filter element and at least one IDT of the third surface acoustic wave filter element are connected to at least one IDT of the first surface acoustic wave filter element.

Abstract: A surface acoustic wave filter device has a balance-unbalance conversion function and substantially equal input impedance and output impedance so as to increase out-of-passband attenuation. The surface acoustic wave filter device includes an unbalanced signal terminal, first and second balanced signal terminals, and first and second surface acoustic wave filters having input and output impedances. In each filter, one of the input and output impedances is approximately four times the other impedance. Additionally, 2n−1 first surface acoustic wave filters are connected between the unbalanced signal terminal and the first balanced signal terminal, and 2n−1 second surface acoustic wave filters are connected between the unbalanced signal terminal and the second balanced signal terminal, where n is an integer of 1 or more. The second surface acoustic wave filters are 180 degrees out-of-phase with respect to the first surface acoustic wave filters.

Abstract: In a surface acoustic wave (SAW) apparatus, a first SAW filter device and a second SAW filter device are disposed on a piezoelectric substrate such that their respective propagation paths overlap. When the center-to-center distance between the first and second SAW filter devices are indicated by d1, and when the thickness of the piezoelectric substrate is indicated by t, the first and second SAW filter devices and the piezoelectric substrate are arranged so as to satisfy the condition d1≦2.3×t or d1≧2.8×t.