Abstract: A semiconductor device and a radio frequency circuit which are appropriate for multiband, multimode performance can be realized as a semiconductor device including a field-effect transistor formed on a semiconductor substrate, and include: ohmic electrodes serving as source and drain electrodes of the field-effect transistor, first and second Schottky electrodes provided between the ohmic electrodes and serving as gate electrodes of the field-effect transistor, and a third Schottky electrode provided and grounded between the first and second Schottky electrodes.

Abstract: An RF power amplifier according to an implementation of the present invention includes: a first power amplifier which linearly amplifies a first RF signal of a first frequency band; a second power amplifier which linearly amplifies a second RF signal of a second frequency band lower than the first frequency band; a third power amplifier which nonlinearly amplifies a third RF signal of the first frequency band; a fourth power amplifier which nonlinearly amplifies a fourth RF signal of the second frequency band, and input lines of the respective power amplifiers do not cross each other on semiconductor substrates, and the output lines of the respective power amplifiers do not cross each other on the semiconductor substrates.

Abstract: To provide a radio frequency power amplifier that realizes a favorable high-frequency characteristic without using an isolator and also achieves low power consumption. The radio frequency power amplifier includes: a power amplifier which amplifies a radio frequency signal; a voltage supplying unit which supplies a collector voltage to the power amplifier; a current supplying unit which supplies a bias current to the power amplifier; and a bias current detecting unit which detects the bias current. The voltage supplying unit has a control unit which sets the power supply voltage at: a first voltage when the detected bias current is lower than a bias-current reference value; and a second voltage lower than the first voltage when the detected bias current is higher than the bias-current reference value.

Abstract: A first FET is inserted in a series position between a signal input terminal and a signal output terminal, while second and third FETs are inserted in a shunt position respectively between the signal input terminal and a ground terminal and between the signal output terminal and a ground terminal. First and second reference voltage terminals and a control terminal are provided. A first reference voltage and a control voltage are applied to the first FET, while a second reference voltage and a control voltage are applied respectively to the second and third FETs, so that the first, second, and third FETs serve as variable resistors. As such, a gain control circuit is constructed. Further, a first resistor is provided in parallel to the first FET, while second and third resistors are provided respectively in series to the second and third FETs.

Abstract: To provide a multiband RF power amplifier which operates with improved isolation at multiple bands and in multiple modes in each of the bands. An RF power amplifier according to an implementation of the present invention includes a first power amplifying circuit, a second power amplifying circuit, a third power amplifying circuit, and a fourth power amplifying circuit, and the first to the fourth power amplifying circuits each include, on a semiconductor substrate, an input pad for wire bonding, an input line, a power amplifier, an output line, and an output pad, and such input lines do not cross each other on chips, and such output lines do not cross each other on the chips.

Abstract: An RF power amplifier according to an implementation of the present invention includes: a first power amplifier which linearly amplifies a first RF signal of a first frequency band; a second power amplifier which linearly amplifies a second RF signal of a second frequency band lower than the first frequency band; a third power amplifier which nonlinearly amplifies a third RF signal of the first frequency band; a fourth power amplifier which nonlinearly amplifies a fourth RF signal of the second frequency band, and input lines of the respective power amplifiers do not cross each other on semiconductor substrates, and the output lines of the respective power amplifiers do not cross each other on the semiconductor substrates.

Abstract: A semiconductor device which detects a power level of a radio-frequency signal includes: a switch FET including: a semiconductor layer; a source electrode and a drain electrode; a first gate electrode; a second gate electrode formed between the first gate electrode and the drain electrode and on the semiconductor layer, each of the first gate electrode and the second gate electrode being in Schottky contact with the semiconductor layer, and the source electrode receiving the radio-frequency signal; a resistor having one end electrically connected to the first gate electrode and an other end electrically connected to the drain electrode via a capacitor; and a power detection terminal electrically connected to a connecting point between the resistor and the capacitor.

Abstract: A semiconductor device and a radio frequency circuit which are appropriate for multiband, multimode performance can be realized as a semiconductor device including a field-effect transistor formed on a semiconductor substrate, and include: ohmic electrodes serving as source and drain electrodes of the field-effect transistor, first and second Schottky electrodes provided between the ohmic electrodes and serving as gate electrodes of the field-effect transistor, and a third Schottky electrode provided and grounded between the first and second Schottky electrodes.

Abstract: An RF power amplifier according to the present invention includes: an RF power amplifying element, a first switch provided in a first transmission path for transmitting a first RF signal output from the RF power amplifying element, a second transmission unit which transmits a second RF signal of higher frequency than the first RF signal output from the RF power amplifying element, and a second second-order harmonic trap circuit connected to an output terminal, and the second transmission unit includes a grounded capacitor, a second transmission path, a Band-I matching circuit, a second switch connected in series to the second transmission path, and the second switch connects the second transmission path to the grounded capacitor when the first RF signal is amplified, and connects the second transmission path to the Band-I matching circuit when the second RF signal is amplified.

Abstract: A radio frequency signal is input to the bases of transistors via respective capacitors, is amplified, and is output from the collectors of the transistors. The emitter of each transistor is grounded. A bias current input from a bias circuit is supplied to the bases of the transistors via respective resistors both during low-output operation and during high-output operation. The collectors of the transistors are connected via an impedance circuit to a bias voltage input terminal. Therefore, during high-output operation, a direct current offset voltage is generated by the impedance circuit based on a portion of a radio frequency signal output from the collectors, thereby further increasing the bias current.

Abstract: A radio-frequency power amplifier device includes an input terminal for which a first radio-frequency signal for a CDMA mode within a first frequency band and a third radio-frequency signal for a TDMA mode within the first frequency band are selectively provided, a second input terminal for which a second radio-frequency signal for a CDMA mode within a second frequency band and a fourth radio-frequency signal for a TDMA mode within the second frequency band are selectively provided, a first power amplifier unit which to amplifies the provided first radio-frequency signal, a second power amplifier unit which amplifies the provided second radio-frequency signal, a third power amplifier unit which amplifies the provided third radio-frequency signal, and a fourth power amplifier unit which amplifies the provided fourth radio-frequency signal. These power amplifier units are arranged in order of the first power amplifier unit to the fourth power amplifier unit.

Abstract: A bias circuit operable to supply a bias current to a first transistor includes: a second transistor having a collector terminal connected to a first power supply; a first resistance element having one end connected to an emitter terminal of the second transistor and having the other end connected to a base terminal of the first transistor; a second resistance element having one end connected to the emitter terminal of the second transistor and having the other end connected to ground potential; at least one third resistance element provided between a base terminal of the second transistor and a second power supply; and a plurality of temperature compensation circuits connected to the base terminal of the second transistor which are operable to control a base potential of the second transistor so that the potential falls as a temperature rises.

Abstract: In a multi-stage amplifier, a power supply circuit and a multiplier perform control so that, when there are manufacturing variations in, for example, inter-stage capacitance, a collector voltage of a stage immediately preceding a final stage is smaller than a collector voltage of the final stage, thereby suppressing variations in AM-PM characteristics.

Abstract: A small, high performance high frequency power amplifier enables easily adjusting and switching the impedance. The high frequency power amplifier module includes a first semiconductor chip including one or a plurality of high frequency amplification devices, and a second semiconductor chip including one or more high frequency matching circuit devices and one or more switching devices. The second semiconductor chip includes the matching circuit for a high frequency amplifier device. The second semiconductor chip also includes a circuit composed of a capacitance and a switching device connected in series or parallel to the capacitance. The switching device switches on or off so that the capacitance is connected or is not connected as a part of the matching circuit.

Abstract: A radio frequency signal is input to the bases of transistors via respective capacitors, is amplified, and is output from the collectors of the transistors. The emitter of each transistor is grounded. A bias current input from a bias circuit is supplied to the bases of the transistors via respective resistors both during low-output operation and during high-output operation. The collectors of the transistors are connected via an impedance circuit to a bias voltage input terminal. Therefore, during high-output operation, a direct current offset voltage is generated by the impedance circuit based on a portion of a radio frequency signal output from the collectors, thereby further increasing the bias current.

Abstract: A radio-frequency power amplifier for preventing a final-stage HBT from being destroyed is provided. To this end, a radio-frequency multistage power amplifier of the present invention includes: a first amplification stage having a first hetero bipolar transistor of which collector output is detected; a second amplification stage which is prior to the first amplification stage and which has a second hetero bipolar transistor in which the detection result is reflected; a first resistor provided between a collector of the second hetero bipolar transistor and a power supply; and a protection circuit which is connected between a collector of the first hetero bipolar transistor and the collector of the second hetero bipolar transistor, detects output from the collector of the first hetero bipolar transistor, and reduces a voltage of the collector of the second hetero bipolar transistor in accordance with the detected output.

Abstract: A radio frequency circuit according to the present invention, is a radio frequency circuit for amplifying a radio frequency signal, the radio frequency circuit comprising: an amplifier circuit for amplifying the radio frequency signal and outputting an amplified signal obtained by the amplification of the radio frequency signal; a load circuit connected to an output of the amplifier circuit; a plurality of transmission lines; a selection circuit for selecting a transmission line among the plurality of transmission lines in accordance with a predetermined parameter of the amplified signal so as to connect the selected transmission line to an output of the load circuit; and a conversion circuit for converting, into a predetermined load impedance, a load impedance looking from the amplifier circuit toward an output side of the amplifier circuit, the conversion being performed in the transmission line selected by the selection circuit.

Abstract: Provided is a matching circuit, radio-frequency power amplifier, and mobile phone whereby the second harmonic can be suppressed and the loss of fundamental due to the self resonant frequency of components can be reduced. The output matching circuit includes: a transmission line through which a radio-frequency signal is transmitted; and resonators each of which includes a capacitor. The resonators respectively have (i) first terminals connected to substantially a same connecting point on the transmission line and (ii) second terminals that are grounded.

Abstract: A small, high performance, multifunctional high frequency circuit that is multiband and multimode compatible reduces loss from a switch formed on the output side of a final stage amplification unit. The final stage amplification unit power amplifies an input signal and outputs an amplified signal. A first matching circuit impedance converts the amplified signal input thereto at a first input impedance, and outputs a first impedance-converted signal at a first output impedance. A control unit that generates a control signal denoting signal path selection information. A switch unit selects one of at least two signal paths based on the control signal, passes the first impedance-converted signal at an on impedance through the selected path, and outputs the pass signal. A second matching circuit impedance converts a pass signal input thereto at a second input impedance, and outputs a second impedance-converted signal at a second output.

Abstract: A first FET is inserted in a series position between a signal input terminal and a signal output terminal, while second and third FETs are inserted in a shunt position respectively between the signal input terminal and a ground terminal and between the signal output terminal and a ground terminal. First and second reference voltage terminals and a control terminal are provided. A first reference voltage and a control voltage are applied to the first FET, while a second reference voltage and a control voltage are applied respectively to the second and third FETs, so that the first, second, and third FETs serve as variable resistors. As such, a gain control circuit is constructed. Further, a first resistor is provided in parallel to the first FET, while second and third resistors are provided respectively in series to the second and third FETs.