Abstract: An amplifier device includes an amplifier including cascade-connected power amplifiers in a plurality of stages and a bias circuit configured to supply bias currents to the amplifier. A bias current supplied to a power amplifier in the first stage of the power amplifiers in the plurality of stages exhibits a positive temperature characteristic. A bias current supplied to a power amplifier in the final stage exhibits a negative temperature characteristic.

Abstract: A switching circuit includes: a substrate including input-and-output terminals; a switch provided to the substrate and including a source terminal, a gate terminal, and a drain terminal, the source terminal being connected to an input end of a power amplifier, the drain terminal being connected to a first input-and-output terminal; a voltage control circuit provided to the substrate and connected to the gate terminal; a switch provided to the substrate and including a source terminal, a gate terminal, and a drain terminal, the source terminal being connected to a second input-and-output terminal, the drain terminal being connected to an output end of the power amplifier; and a voltage control circuit provided to the substrate to be apart from the voltage control circuit and connected to the gate terminal.

Abstract: An amplifier circuit includes an input terminal, an output terminal, a transistor provided in between the input terminal and the output terminal, and a coiled or meandered inductor. The transistor has a gate, a source, and a drain, and of these gate, source, and drain, two terminals are connected to ground terminals that are different from each other. The inductor is connected between the ground terminals to which the foregoing two terminals are connected.

Abstract: An amplifier circuit includes: a transistor provided between an input terminal and an output terminal and having a gate connected to the input terminal, a source connected to a ground, and a drain connected to the output terminal; an inductor connected between the source and the ground; an inductor connected between the gate and the input terminal, and switches connected to at least one of the inductors and configured to change a mutual inductance of the inductors.

Abstract: An amplifier circuit amplifies a radio-frequency signal. The amplifier circuit includes an amplifier, an input matching circuit connected to an input side of the amplifier and matches impedance, and a protection circuit connected to a node in a path within a path between an input matching circuit and the amplifier. The protection circuit includes a first diode connected between the node and a ground, and a second diode connected in parallel with the first diode and connected in a direction opposite to the first diode between the node and the ground. A threshold voltage of each of the first diode and the second diode is greater than a maximum voltage amplitude of the input signal at the node and is less than a difference between a withstand voltage of the amplifier and the bias voltage.

Abstract: An amplifying apparatus includes a transistor arranged on a substrate and constituting an amplifier, an input terminal for inputting a high-frequency signal to the amplifier, an output terminal for outputting the high-frequency signal amplified by the amplifier, a first inductor formed in or on the substrate and connected between a source of the transistor and a ground, and a second inductor formed in or on the substrate and connected between a gate of the transistor and the input terminal. When the substrate is viewed in a plan view, the first inductor and the second inductor do not overlap each other. The first inductor and the second inductor are magnetically coupled to each other.

Abstract: An amplifier device includes an amplifier including cascade-connected power amplifiers in a plurality of stages and a bias circuit configured to supply bias currents to the amplifier. A bias current supplied to a power amplifier in the first stage of the power amplifiers in the plurality of stages exhibits a positive temperature characteristic. A bias current supplied to a power amplifier in the final stage exhibits a negative temperature characteristic.

Abstract: An amplifier circuit includes: a transistor provided between an input terminal and an output terminal and having a gate connected to the input terminal, a source connected to a ground, and a drain connected to the output terminal; an inductor connected between the source and the ground; an inductor connected between the gate and the input terminal, and switches connected to at least one of the inductors and configured to change a mutual inductance of the inductors.

Abstract: An amplifier circuit amplifies a radio-frequency signal. The amplifier circuit includes an amplifier, an input matching circuit connected to an input side of the amplifier and matches impedance, and a protection circuit connected to a node in a path within a path between an input matching circuit and the amplifier. The protection circuit includes a first diode connected between the node and a ground, and a second diode connected in parallel with the first diode and connected in a direction opposite to the first diode between the node and the ground. A threshold voltage of each of the first diode and the second diode is greater than a maximum voltage amplitude of the input signal at the node and is less than a difference between a withstand voltage of the amplifier and the bias voltage.

Abstract: A voltage supply circuit includes a level shifter that switches between voltages of two voltage input units and that outputs one of the voltages, a charge pump that transforms a voltage of an input power supply and that applies the transformed voltage to the level shifter, and a charge pump control circuit. The voltage supply circuit controls supply and interruption of a predetermined voltage to a voltage-supplied circuit (RF switch 20). The charge pump control circuit causes the charge pump to perform a continuous operation in an on-mode and to perform an intermittent operation in an off-mode, the off-mode representing a state in which the voltage supply to the voltage-supplied circuit (RF switch 20) is stopped, the on-mode representing a state in which the predetermined voltage is supplied.

Abstract: An amplifying apparatus includes a transistor arranged on a substrate and constituting an amplifier, an input terminal for inputting a high-frequency signal to the amplifier, an output terminal for outputting the high-frequency signal amplified by the amplifier, a first inductor formed in or on the substrate and connected between a source of the transistor and a ground, and a second inductor formed in or on the substrate and connected between a gate of the transistor and the input terminal. When the substrate is viewed in a plan view, the first inductor and the second inductor do not overlap each other. The first inductor and the second inductor are magnetically coupled to each other.

Abstract: A voltage supply circuit includes a level shifter that switches between voltages of two voltage input units and that outputs one of the voltages, a charge pump that transforms a voltage of an input power supply and that applies the transformed voltage to the level shifter, and a charge pump control circuit. The voltage supply circuit controls supply and interruption of a predetermined voltage to a voltage-supplied circuit (RF switch 20). The charge pump control circuit causes the charge pump to perform a continuous operation in an on-mode and to perform an intermittent operation in an off-mode, the off-mode representing a state in which the voltage supply to the voltage-supplied circuit (RF switch 20) is stopped, the on-mode representing a state in which the predetermined voltage is supplied.

Abstract: Provided is an amplification circuit that amplifies an input signal and outputs an amplified signal. The amplification circuit includes: an amplification element that outputs the amplified signal from an output terminal thereof; an inductor having one end to which a power supply voltage is supplied and another end that is connected to the output terminal of the amplification element; a variable resistor that is connected in parallel with the inductor; and a resistance value adjusting circuit that adjusts a resistance value of the variable resistor in accordance with the temperature.

Abstract: Provided is an amplification circuit that amplifies an input signal and outputs an amplified signal. The amplification circuit includes: an amplification element that outputs the amplified signal from an output terminal thereof; an inductor having one end to which a power supply voltage is supplied and another end that is connected to the output terminal of the amplification element; a variable resistor that is connected in parallel with the inductor; and a resistance value adjusting circuit that adjusts a resistance value of the variable resistor in accordance with the temperature.

Abstract: Provided is an amplification circuit that amplifies an input signal and outputs an amplified signal. The amplification circuit includes: an amplification element that outputs the amplified signal from an output terminal thereof; an inductor having one end to which a power supply voltage is supplied and another end that is connected to the output terminal of the amplification element; a variable resistor that is connected in parallel with the inductor; and a resistance value adjusting circuit that adjusts a resistance value of the variable resistor in accordance with the temperature.

Abstract: Provided is an amplification circuit that amplifies an input signal and outputs an amplified signal. The amplification circuit includes: an amplification element that outputs the amplified signal from an output terminal thereof; an inductor having one end to which a power supply voltage is supplied and another end that is connected to the output terminal of the amplification element; a variable resistor that is connected in parallel with the inductor; and a resistance value adjusting circuit that adjusts a resistance value of the variable resistor in accordance with the temperature.

Abstract: Consumption current may be reduced in a power amplifier module in which a power supply voltage supplied to a power amplification transistor is controlled according to the level of output power. The power amplifier module includes an amplification transistor supplied with the power supply voltage according to the level of output power to amplify a radio-frequency signal, a bias control circuit for generating a bias voltage according to the power supply voltage, and a bias circuit for supplying a bias current according to the bias voltage to the amplification transistor, wherein current flowing through the amplification transistor when the radio-frequency signal is not input is varied according to the level of output power.

Abstract: Consumption current may be reduced in a power amplifier module in which a power supply voltage supplied to a power amplification transistor is controlled according to the level of output power. The power amplifier module includes an amplification transistor supplied with the power supply voltage according to the level of output power to amplify a radio-frequency signal, a bias control circuit for generating a bias voltage according to the power supply voltage, and a bias circuit for supplying a bias current according to the bias voltage to the amplification transistor, wherein current flowing through the amplification transistor when the radio-frequency signal is not input is varied according to the level of output power.

Abstract: There is provided a bias circuit including a power amplifier in which influence of variation of a gate length L is reduced and variation of a gain among products is low. Two NPN- and PNP-type current mirror circuits 101 (NPN type) and 102 (PNP type) are inserted on an input side of a bias circuit 103. It is designed that a gate length of a transistor Q1 on an output side of the current mirror circuit 101 is longer than that of the other transistor. In this manner, even when an error is generated, influence of the error can be suppressed to be small.

Abstract: There is provided a bias circuit that can operate even at low voltage and control a current reflecting a change in drain voltage. A first current mirror circuit for feeding back a drain terminal current of an FET which receives an output of an operational amplifier at a gate terminal to an input terminal of the operational amplifier and a second current mirror circuit are coupled in parallel. A variable voltage is coupled to the first current mirror circuit, and a fixed voltage is coupled to the second current mirror circuit. Even if the variable voltage becomes lower than the threshold voltage of FETs configuring the first current mirror circuit, the second current mirror circuit feeds back the current to the input terminal of the operational amplifier with reliability.