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 amplifier circuit has an amplification path including an amplifier and a bypass path configured to bypass at least the amplifier. The bypass path includes a switch coupled in series on the bypass path and another switch coupled in series between the bypass path and ground. The amplification path further includes an inductor coupled on an output side with respect to the amplifier and a switch coupled between the inductor and ground on a path between the inductor and the amplifier.

Abstract: An amplifier circuit that amplifies a high frequency signal includes a transistor that is an example of an amplifier integrated into an IC device and an inductor connected to an input terminal of the transistor, and the inductor includes a first inductor integrated into the IC device and a second inductor connected in series to the first inductor and included in a first component different from the IC device.

Abstract: An amplifier circuit includes a first transistor including a signal input portion into which a signal is input from the outside, and a load inductor connected between the first transistor and a power supply line. In addition, the amplifier circuit includes a feedback circuit, which is connected between any position between the load inductor and the first transistor and the signal input portion of the first transistor. The gain and linearity are determined as appropriate in accordance with the amount of feedback from this feedback circuit.

Abstract: A radio-frequency module (10) includes an IC chip (20) and a mounted component (41, 42, 43) mounted on the IC chip (20). The IC chip (20) includes a core substrate (21) composed of a semiconductor having a first main surface (211) and a second main surface (212) opposed to each other, and a metal wiring layer (22) formed on the first main surface (211) of the core substrate (21) and having a contact surface in contact with the first main surface (211) and a third main surface (221) opposed to the contact surface. The mounted component (41, 42, 43) is mounted at the third main surface (221) side.

Abstract: An amplifier circuit has an amplification path including an amplifier and a bypass path configured to bypass at least the amplifier. The bypass path includes a switch coupled in series on the bypass path and another switch coupled in series between the bypass path and ground. The amplification path further includes an inductor coupled on an output side with respect to the amplifier and a switch coupled between the inductor and ground on a path between the inductor and the amplifier.

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 amplifier circuit that amplifies a high frequency signal includes a transistor that is an example of an amplifier integrated into an IC device and an inductor connected to an input terminal of the transistor, and the inductor includes a first inductor integrated into the IC device and a second inductor connected in series to the first inductor and included in a first component different from the IC device.

Abstract: A radio-frequency module (10) includes an IC chip (20) and a mounted component (41, 42, 43) mounted on the IC chip (20). The IC chip (20) includes a core substrate (21) composed of a semiconductor having a first main surface (211) and a second main surface (212) opposed to each other, and a metal wiring layer (22) formed on the first main surface (211) of the core substrate (21) and having a contact surface in contact with the first main surface (211) and a third main surface (221) opposed to the contact surface. The mounted component (41, 42, 43) is mounted at the third main surface (221) side.

Abstract: An amplifier circuit includes a first transistor including a signal input portion into which a signal is input from the outside, and a load inductor connected between the first transistor and a power supply line. In addition, the amplifier circuit includes a feedback circuit, which is connected between any position between the load inductor and the first transistor and the signal input portion of the first transistor. The gain and linearity are determined as appropriate in accordance with the amount of feedback from this feedback circuit.

Abstract: An amplifier according to an embodiment of the present disclosure includes a first transistor and a first matching circuit. The first matching circuit is connected between an input terminal and a control terminal of the first transistor. A first terminal of the first transistor is connected to a ground. A second terminal of the first transistor is connected to a power supply and an output terminal. The first matching circuit includes a first inductor, a second inductor, and a first switch. The first inductor has an end connected to the control terminal. The second inductor has an end connected to the other end of the first inductor. The first switch is configured to selectively switch between electrical continuity between the input terminal and the other end of the first inductor and electrical continuity between the input terminal and the other end of the second inductor.

Abstract: An amplifier according to an embodiment of the present invention includes a first transistor and a second transistor that are connected between a ground point and a power supply. A control terminal of the first transistor is connected to an input terminal. A first terminal of the first transistor is connected to the ground point. A second terminal of the second transistor is connected to an output terminal. The amplifier further includes an impedance element and a variable resistance unit. The impedance element is connected between the second terminal of the second transistor and the power supply. The variable resistance unit is connected between the second terminal of the first transistor and the first terminal of the second transistor.

Abstract: An amplifier according to an embodiment of the present disclosure includes a first transistor and a first matching circuit. The first matching circuit is connected between an input terminal and a control terminal of the first transistor. A first terminal of the first transistor is connected to a ground. A second terminal of the first transistor is connected to a power supply and an output terminal. The first matching circuit includes a first inductor, a second inductor, and a first switch. The first inductor has an end connected to the control terminal. The second inductor has an end connected to the other end of the first inductor. The first switch is configured to selectively switch between electrical continuity between the input terminal and the other end of the first inductor and electrical continuity between the input terminal and the other end of the second inductor.

Abstract: An amplifier according to an embodiment of the present disclosure includes a first transistor and a first matching circuit. The first matching circuit is connected between an input terminal and a control terminal of the first transistor. The first matching circuit includes a first inductor, a second inductor, and a first switch. The first inductor has an end connected to the control terminal. The second inductor has an end connected to the other end of the first inductor. The first switch is configured to selectively switch between electrical continuity between the input terminal and the other end of the first inductor and electrical continuity between the input terminal and the other end of the second inductor.

Abstract: An amplifier according to an embodiment of the present disclosure includes a first transistor and a first matching circuit. The first matching circuit is connected between an input terminal and a control terminal of the first transistor. The first matching circuit includes a first inductor, a second inductor, and a first switch. The first inductor has an end connected to the control terminal. The second inductor has an end connected to the other end of the first inductor. The first switch is configured to selectively switch between electrical continuity between the input terminal and the other end of the first inductor and electrical continuity between the input terminal and the other end of the second inductor.

Abstract: An amplifier according to an embodiment of the present invention includes a first transistor and a second transistor that are connected between a ground point and a power supply. A control terminal of the first transistor is connected to an input terminal. A first terminal of the first transistor is connected to the ground point. A second terminal of the second transistor is connected to an output terminal. The amplifier further includes an impedance element and a variable resistance unit. The impedance element is connected between the second terminal of the second transistor and the power supply. The variable resistance unit is connected between the second terminal of the first transistor and the first terminal of the second transistor.

Abstract: A radio-frequency amplifier circuit includes first and second FETs cascode-connected to each other. The gate of the first FET is connected to a radio-frequency input terminal, and the drain of the second FET is connected to a radio-frequency output terminal. The source of the first FET is connected to a ground, and the drain of the first FET and the source of the second FET are connected to each other. A drive voltage is applied to the drain of the second FET. A bias setting unit is connected to the gate of the second FET. The bias setting unit sets a second control voltage to be applied to the second FET so that a node voltage between the drain of the first FET and the source of the second FET will be substantially half of the drive voltage.

Abstract: A radio-frequency amplifier circuit includes first and second FETs cascode-connected to each other. The gate of the first FET is connected to a radio-frequency input terminal, and the drain of the second FET is connected to a radio-frequency output terminal. The source of the first FET is connected to a ground, and the drain of the first FET and the source of the second FET are connected to each other. A drive voltage is applied to the drain of the second FET. A bias setting unit is connected to the gate of the second FET. The bias setting unit sets a second control voltage to be applied to the second FET so that a node voltage between the drain of the first FET and the source of the second FET will be substantially half of the drive voltage.