Abstract: A radio frequency module includes a first power amplifier, a second power amplifier, a filter, a switch, and a matching circuit. The first power amplifier outputs a first amplified signal. The second power amplifier outputs a second amplified signal. The filter allows the first amplified signal and the second amplified signal to pass through. The switch has a first terminal and a second terminal. The first terminal is connected to an output portion of the first power amplifier. The second terminal is connected to the filter. The switch changes over connection and disconnection of the first terminal and the second terminal. The matching circuit is connected between an output portion of the second power amplifier and a signal path between the second terminal of the switch and the filter.

Abstract: A radio frequency module includes a transmit filter that allows a transmit signal of a band A for FDD to pass through, a receive filter that allows a receive signal of the band A to pass through, a filter that allows a transmit/receive signal of a band B for TDD to pass through, power amplifiers, a low noise amplifier, a switch between connecting the receive filter to the low noise amplifier and connecting the filter to the low noise amplifier, a switch between connecting the filter to the power amplifier and connecting the filter to the low noise amplifier, a matching circuit connected between the power amplifier and the transmit filter, a matching circuit connected between the power amplifier and the switch, and a module board. On the module board, each of the power amplifiers and the switch is arranged in between the matching circuit and the matching circuit.

Abstract: To provide a high-frequency circuit and a communication device by which a harmonic component in differential amplification can be attenuated. The high-frequency circuit includes a differential amplifier circuit. The differential amplifier circuit includes a first amplifying element, a second amplifying element, first wiring, second wiring, and a series circuit. The first amplifying element includes a first input terminal and a first output terminal. The second amplifying element includes a second input terminal and a second output terminal. The first wiring is connected to the first output terminal. The second wiring is connected to the second output terminal. The series circuit is connected between the first wiring and the second wiring. The series circuit includes a first inductor, a second inductor, and a capacitor.

Abstract: A radio frequency module includes a transmit filter that allows a transmit signal of a band A for FDD to pass through, a receive filter that allows a receive signal of the band A to pass through, a filter that allows a transmit/receive signal of a band B for TDD to pass through, power amplifiers, a low noise amplifier, a switch between connecting the receive filter to the low noise amplifier and connecting the filter to the low noise amplifier, a switch between connecting the filter to the power amplifier and connecting the filter to the low noise amplifier, a matching circuit connected between the power amplifier and the transmit filter, a matching circuit connected between the power amplifier and the switch, and a module board. On the module board, each of the power amplifiers and the switch is arranged in between the matching circuit and the matching circuit.

Abstract: A radio-frequency circuit includes an amplifier circuit, a bias circuit, a bias control circuit, a comparing section, a signal input terminal, an antenna terminal, an attenuation circuit, and a control unit. The amplifier circuit includes a specific transistor. The bias circuit supplies a bias current or a bias voltage to the input terminal of the specific transistor. The bias control circuit supplies a control current or a control voltage to the bias circuit. The comparing section compares a threshold voltage with a power supply voltage of a power supply terminal connected to the output terminal of the specific transistor. The attenuation circuit is connected in a signal path between the signal input terminal and the antenna terminal and is capable of attenuating the radio-frequency signal. The control unit changes an attenuation of the attenuation circuit in accordance with a compared result of the comparing section.

Abstract: A radio-frequency circuit includes an amplifier circuit, a bias circuit, a bias control circuit, a comparing section, a variable resistance circuit, and a control unit. The amplifier circuit includes a transistor that amplifies a radio-frequency signal input to an input terminal and outputs the radio-frequency signal from an output terminal. The bias circuit supplies a bias current or a bias voltage to the input terminal of the transistor. The comparing section compares a threshold voltage with a power supply voltage of a power supply terminal connected to the output terminal of the transistor. The variable resistance circuit is connected between the power supply terminal and the output terminal. The variable resistance circuit includes a parallel circuit made up of a resistive element and a switch element. The control unit changes a resistance value of the variable resistance circuit in accordance with a compared result of the comparing section.

Abstract: A power amplifier circuit includes an amplifier circuit, a bias circuit, a detector, and a control circuit. The amplifier circuit includes a first bipolar transistor. The bias circuit includes an emitter follower. The emitter follower includes a second bipolar transistor and supplies a bias current to the base of the first bipolar transistor. The detector detects the voltage of a power supply terminal connected to the collector of the first bipolar transistor. The control circuit includes a current limiting circuit disposed between a battery terminal and the collector of the second bipolar transistor. The control circuit changes an upper limit value of a control current to be supplied to the collector of the second bipolar transistor, based on the voltage detected by the detector.

Abstract: A power amplification module includes an amplification circuit, a biasing circuit, a constant voltage generation circuit, a constant current generation circuit, a switching unit, and a control unit for controlling a switching operation of the switching unit, and the control unit causes the switching unit to perform switching to connect the constant voltage generation circuit to an input end of the biasing circuit when an output mode is a first output mode in which a high-frequency signal having no less than a predetermined output power is outputted from the amplification circuit, and causes the switching unit to perform switching to connect the constant current generation circuit to the input end of the biasing circuit when the output mode is a second output mode in which a power less than the predetermined output power is outputted from the amplification circuit.

Abstract: A power amplification module includes an amplification circuit, a biasing circuit, a constant voltage generation circuit, a constant current generation circuit, a switching unit, and a control unit for controlling a switching operation of the switching unit, and the control unit causes the switching unit to perform switching to connect the constant voltage generation circuit to an input end of the biasing circuit when an output mode is a first output mode in which a high-frequency signal having no less than a predetermined output power is outputted from the amplification circuit, and causes the switching unit to perform switching to connect the constant current generation circuit to the input end of the biasing circuit when the output mode is a second output mode in which a power less than the predetermined output power is outputted from the amplification circuit.

Abstract: A high-frequency front end circuit performs reception/transmission simultaneously, and includes a transmitter circuit and a receiver circuit. The transmitter circuit includes a transmit filter passing a signal in the transmit frequency band. The receiver circuit includes a receive filter, an LNA, and a filter circuit. The receive filter passes a signal in the receive frequency band different from the transmit frequency band. The LNA receives and amplifies a signal that has been output from the receive filter. The filter circuit is connected between the receive filter and the LNA. The filter circuit attenuates a component, which is included in the signal received by the LNA, of the frequency indicating the difference between the center frequency of the transmit frequency band and the center frequency of the receive frequency band.

Abstract: A high-frequency front end circuit performs reception/transmission simultaneously, and includes a transmitter circuit and a receiver circuit. The transmitter circuit includes a transmit filter passing a signal in the transmit frequency band. The receiver circuit includes a receive filter, an LNA, and a filter circuit. The receive filter passes a signal in the receive frequency band different from the transmit frequency band. The LNA receives and amplifies a signal that has been output from the receive filter. The filter circuit is connected between the receive filter and the LNA. The filter circuit attenuates a component, which is included in the signal received by the LNA, of the frequency indicating the difference between the center frequency of the transmit frequency band and the center frequency of the receive frequency band.

Abstract: A semiconductor device includes a power amplifier for amplifying RF signals in multiple frequency bands, an output matching circuit connected to an output of the power amplifier, a first capacitor connected at a first end to an output of the output matching circuit, multiple output paths, a switch connected to a second end of the first capacitor and directing each of the RF signals to a respective one of the output paths in accordance with frequency band of the each of the RF signals, and multiple second capacitors. Each second capacitor is connected in series to a respective one of the output paths. The switch and either the first capacitor or the second capacitors, or both the first and second capacitors, are integrated as a single monolithic microwave integrated circuit.

Abstract: A semiconductor device includes a power amplifier for amplifying RF signals in multiple frequency bands, an output matching circuit connected to an output of the power amplifier, a first capacitor connected at a first end to an output of the output matching circuit, multiple output paths, a switch connected to a second end of the first capacitor and directing each of the RF signals to a respective one of the output paths in accordance with frequency band of the each of the RF signals, and multiple second capacitors. Each second capacitor is connected in series to a respective one of the output paths. The switch and either the first capacitor or the second capacitors, or both the first and second capacitors, are integrated as a single monolithic microwave integrated circuit.