Abstract: A power amplifier circuit includes a first transistor having a base or gate connected to a signal path, an emitter or source grounded via a first conductor, and a collector or drain, the first transistor amplifying an input signal supplied to the base or gate thereof along the signal path and outputting the amplified signal from the collector or drain thereof; a first element in a preceding stage of the first transistor, the first element having a first end connected to the signal path such that the first element is connected along a path branched from the signal path, and a second end grounded via a second conductor; and a first capacitor having a first end connected to a node between the emitter or source of the first transistor and the first conductor, and a second end connected to a node between the first element and the second conductor.

Abstract: A power amplifier circuit includes a transistor, a bias current source, and an adjustment circuit. The transistor amplifies an RF signal when supplied with a variable power supply voltage. The bias current source supplies a bias current to the base of the transistor through a first current path. The adjustment circuit increases a current flowing from the bias current source to an input terminal of a matching circuit through a second current path as the variable power supply voltage decreases, and decreases the bias current flowing from the bias current source to the base of the transistor through the first current path as the current flowing from the bias current source to the input terminal through the second current path increases.

Abstract: A semiconductor device includes a semiconductor substrate, a transistor, and a first harmonic termination circuit. The transistor is formed at the semiconductor substrate. The transistor amplifies an input signal supplied to an input end and outputs an amplified signal through an output end. The first harmonic termination circuit attenuates a harmonic component included in the amplified signal. The first harmonic termination circuit is formed at the semiconductor substrate such that one end of the first harmonic termination circuit is connected to the output end of the transistor and the other end of the first harmonic termination circuit is connected to a ground end of the transistor.

Abstract: A power amplifier module includes a first power amplifier circuit configured to output a first amplified signal obtained by amplifying an input signal; a second power amplifier circuit configured to output a second amplified signal obtained by amplifying the first amplified signal; and a matching network connected between the first power amplifier circuit and the second power amplifier circuit. The matching network includes a first capacitor connected in series between the first power amplifier circuit and the second power amplifier circuit, a second capacitor connected in series between the first capacitor and the second power amplifier circuit, a first inductor connected between a point between the first capacitor and the second capacitor and a ground, and a second inductor connected in series between the first power amplifier circuit and the first capacitor.

Abstract: A power amplifier circuit includes a transistor, a bias current source, and an adjustment circuit. The transistor amplifies an RF signal when supplied with a variable power supply voltage. The bias current source supplies a bias current to the base of the transistor through a first current path. The adjustment circuit increases a current flowing from the bias current source to an input terminal of a matching circuit through a second current path as the variable power supply voltage decreases, and decreases the bias current flowing from the bias current source to the base of the transistor through the first current path as the current flowing from the bias current source to the input terminal through the second current path increases.

Abstract: Disclosed is a high-frequency power amplifier device capable of reducing a talk current. For example, the high-frequency power amplifier device has first and second power amplifier circuits, first and second transmission lines, and a region in which the first and second transmission lines are disposed close to each other. Either the first or second power amplifier circuit becomes activated in accordance with an output level. When the second power amplifier circuit is activated, currents flowing in the first and second transmission lines are transmitted in the same direction so that magnetic coupling occurs to strengthen each transmission line's magnetic force. When, on the other hand, the first power amplifier circuit is activated, currents flowing in the first and second transmission lines are transmitted in the opposite directions so that magnetic coupling occurs to weaken each transmission line's magnetic force.

Abstract: Disclosed is a high-frequency power amplifier device capable of reducing a talk current. For example, the high-frequency power amplifier device has first and second power amplifier circuits, first and second transmission lines, and a region in which the first and second transmission lines are disposed close to each other. Either the first or second power amplifier circuit becomes activated in accordance with an output level. When the second power amplifier circuit is activated, currents flowing in the first and second transmission lines are transmitted in the same direction so that magnetic coupling occurs to strengthen each transmission line's magnetic force. When, on the other hand, the first power amplifier circuit is activated, currents flowing in the first and second transmission lines are transmitted in the opposite directions so that magnetic coupling occurs to weaken each transmission line's magnetic force.

Abstract: The RF power amplifier apparatus has an RF power amplifier and a power-supply circuit. The power-supply circuit controls the level of a source voltage supplied to the RF power amplifier in response to the level of a power-control signal. A sensing resistance produces a sense signal Vsen corresponding to a source current with respect to a source voltage. The current-control unit controls the source current ILDO in response to the sense signal Vsen. When Vsen coincides with an allowable sense signal level Vsh corresponding to a source current allowable level ILDO(Max), the current-control unit controls the source current ILDO to a limit current smaller than the allowable level ILDO(Max). Preferably, the limit current is a shutdown current when a shutdown switch is in an OFF state. Thus, the draining of the battery of a mobile-phone terminal can be reduced even when an impedance mismatch condition lasts for a long time.

Abstract: The RF power amplifier apparatus has an RF power amplifier and a power-supply circuit. The power-supply circuit controls the level of a source voltage supplied to the RF power amplifier in response to the level of a power-control signal. A sensing resistance produces a sense signal Vsen corresponding to a source current with respect to a source voltage. The current-control unit controls the source current ILDO in response to the sense signal Vsen. When Vsen coincides with an allowable sense signal level Vsh corresponding to a source current allowable level ILDO(Max), the current-control unit controls the source current ILDO to a limit current smaller than the allowable level ILDO(Max). Preferably, the limit current is a shutdown current when a shutdown switch is in an OFF state. Thus, the draining of the battery of a mobile-phone terminal can be reduced even when an impedance mismatch condition lasts for a long time.

Abstract: The RF power amplifier apparatus has an RF power amplifier and a power-supply circuit. The power-supply circuit controls the level of a source voltage supplied to the RF power amplifier in response to the level of a power-control signal. A sensing resistance produces a sense signal Vsen corresponding to a source current with respect to a source voltage. The current-control unit controls the source current ILDO in response to the sense signal Vsen. When Vsen coincides with an allowable sense signal level Vsh corresponding to a source current allowable level ILDO(Max), the current-control unit controls the source current ILDO to a limit current smaller than the allowable level ILDO(Max). Preferably, the limit current is a shutdown current when a shutdown switch is in an OFF state. Thus, the draining of the battery of a mobile-phone terminal can be reduced even when an impedance mismatch condition lasts for a long time.

Abstract: The RF power amplifier apparatus has an RF power amplifier RFPA and a power-supply circuit Pwr_Cnt. The power-supply circuit controls the level of a source voltage VLDO supplied to the RF power amplifier in response to the level of a power-control signal Vapc. The sensing resistance Rsen produces a sense signal Vsen corresponding to a source current ILDO with respect to a source voltage. The current-control unit Cmp1, Cmp2, FF1, NAND3 and Qp4 controls the source current ILDO in response to the sense signal Vsen. When Vsen coincides with an allowable sense signal level Vsh corresponding to a source current allowable level ILDO (Max), the current-control unit controls the source current ILDO to a limit current smaller than the allowable level ILDO (Max). Preferably, the limit current is a shutdown current when a shutdown switch is in OFF state. Thus, the drain of the battery of a mobile-phone terminal can be reduced even when an impedance mismatch condition lasts for a long time.