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 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 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: 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 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: 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: A transmitting apparatus of the present invention includes an orthogonal modulator for generating a modulated signal by using an input signal; a polar-modulation-mode transmission circuit which includes a first power amplifier whose input terminal receives a phase component of the modulated signal generated by the orthogonal modulator and whose power supply terminal receives an amplitude component of the modulated signal generated by the orthogonal modulator, and which polar-modulates the modulated signal; an orthogonal-modulation-mode transmission circuit which includes a second power amplifier whose input terminal receives the modulated signal generated by the orthogonal modulator and whose power supply terminal receives a constant voltage, and which transmits the modulated signal; and a switch for connecting an output of the orthogonal modulator with an input of the polar-modulation-mode transmission circuit at the time of a high output, and for connecting the output of the orthogonal modulator and an inpu

Abstract: A radio frequency power amplifier 1 includes a former-stage transistor 2, a latter-stage transistor 3, and an inter-stage matching circuit 4 for connecting the former-stage transistor 2 and the latter-stage transistor 3. The inter-stage matching circuit 4 includes a high-pass filter circuit including a transfer line m1, a capacitor C1 and a capacitor C2; and a transfer line m2 with which a passage phase of a secondary harmonic signal is 15 degrees or greater.

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 signal RF is input to a base of each of transistors TR1 through TRn via a corresponding capacitor among capacitors C1 through Cn, is amplified, and is output from a collector of each of the transistors TR1 through TRn. An emitter of each of the transistors TR1 through TRn is grounded. A bias voltage DC given from a bias circuit Bias is supplied to the base of each of the transistors TR1 through TRn via a corresponding resistor among resistors Ra1 through Ran. A signal line for the bias voltage DC is connected to an input line for the radio frequency signal RF via the bridge resistor R in a direct current manner.

Abstract: A high-frequency power amplifier with a temperature compensation function for power amplifying a high-frequency signal, includes: a power amplifying transistor having an emitter grounded; a high power output bias circuit that supplies a high power output current corresponding to a high power output of the high-frequency power amplifier to the power amplifying transistor; and a low power output bias circuit that supplies a low power output current corresponding to a low power output of the high-frequency power amplifier to the power amplifying transistor.

Abstract: The transistor circuit 1 includes a plurality of transistor cells 10 each having a transistor 11, a base ballast resistor 12, a capacitor 13, and an inductor 14. The transistors 11 have the respective collectors commonly connected to a collector terminal 1c of the transistor circuit 1 and the respective emitters commonly connected to an emitter terminal 1e thereof. Each base ballast resistor 12 is connected to bases of the transistor 11 at one end and to a base terminal 1b of the transistor circuit 1 at the other end. The capacitor 13 is serially connected to the inductor 14, thus to form a serial resonant circuit 15, which is connected in parallel with the base ballast resistor 12 and provided between the bases of the transistor 11 and the base terminal 1b of the transistor circuit 1 and connected thereto.

Abstract: A high-frequency power amplifier with a temperature compensation function for power amplifying a high-frequency signal, includes: a power amplifying transistor having an emitter grounded; a high power output bias circuit that supplies a high power output current corresponding to a high power output of the high-frequency power amplifier to the power amplifying transistor; and a low power output bias circuit that supplies a low power output current corresponding to a low power output of the high-frequency power amplifier to the power amplifying transistor.

Abstract: A radio frequency power amplifier 1 includes a former-stage transistor 2, a latter-stage transistor 3, and an inter-stage matching circuit 4 for connecting the former-stage transistor 2 and the latter-stage transistor 3. The inter-stage matching circuit 4 includes a high-pass filter circuit including a transfer line m1, a capacitor C1 and a capacitor C2; and a transfer line m2 with which a passage phase of a secondary harmonic signal is 15 degrees or greater.

Abstract: A radio frequency signal RF is input to a base of each of transistors TR1 through TRn via a corresponding capacitor among capacitors C1 through Cn, is amplified, and is output from a collector of each of the transistors TR1 through TRn. An emitter of each of the transistors TR1 through TRn is grounded. A bias voltage DC given from a bias circuit Bias is supplied to the base of each of the transistors TR1 through TRn via a corresponding resistor among resistors Ra1 through Ran. A signal line for the bias voltage DC is connected to an input line for the radio frequency signal RF via the bridge resistor R in a direct current manner.

Abstract: The transistor circuit 1 includes a plurality of transistor cells 10 each having a transistor 11, a base ballast resistor 12, a capacitor 13, and an inductor 14. The transistors 11 have the respective collectors commonly connected to a collector terminal 1c of the transistor circuit 1 and the respective emitters commonly connected to an emitter terminal 1e thereof. Each base ballast resistor 12 is connected to bases of the transistor 11 at one end and to a base terminal 1b of the transistor circuit 1 at the other end. The capacitor 13 is serially connected to the inductor 14, thus to form a serial resonant circuit 15, which is connected in parallel with the base ballast resistor 12 and provided between the bases of the transistor 11 and the base terminal 1b of the transistor circuit 1 and connected thereto.