Abstract: A power amplifier includes: an amplifier having an input terminal and including an amplifying transistor having a threshold voltage; a transistor supplying a bias to the input terminal of the amplifier according to an on/off signal; a capacitor connected between the input terminal of the amplifier and a grounding point; a resistor connected between the input terminal of the amplifier and the grounding point, in parallel with the capacitor; and a diode connected in series with the resistor. The diode has a threshold voltage that is lower than the threshold voltage of the amplifying transistor.

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 transistor includes: a semiconductor substrate; a first electrode on the semiconductor substrate and having first and second portions; a second electrode on the semiconductor substrate and spaced apart from the first electrode; a control electrode on the semiconductor substrate and disposed between the first electrode and the second electrode; and a first heat sink plate joined to the second portion of the first electrode without being joined to the first portion of the first electrode.

Abstract: A first amplifier is connected between an input terminal and an output terminal. A first junction point is located between the input terminal and an input of the first amplifier. A second junction point is located between the output terminal and an output of the first amplifier. A second amplifier is connected in parallel with the first amplifier, between the first junction point and the second junction point. A third junction point is located between an output of the second amplifier and the second junction point. A first capacitor and a switch are connected in series between the third junction point and ground. The second junction point is the lowest impedance point along a power amplification path that includes the input terminal, the first amplifier, and the output terminal. The switch is turned off/on when the second/first amplifier is turned on.

Abstract: A power amplifier includes an input terminal into which an input signal is input; a first amplification element amplifying the input signal; a second amplification element amplifying an output signal of the first amplification element; an output terminal from which an output signal of the second amplification element is output; a first matching circuit connected between an output of the second amplification element and the output terminal; a first switch connected between an output of the first amplification element and an input of the second amplification element; a second switch having a first end connected to the output of the first amplification element, and a second end; and a second matching circuit having a first end connected to the second end of the second switch, and a second end directly connected to the output of the second amplification element.

Abstract: A power amplifier includes: an amplifier having an input terminal and including an amplifying transistor having a threshold voltage; a transistor supplying a bias to the input terminal of the amplifier according to an on/off signal; a capacitor connected between the input terminal of the amplifier and a grounding point; a resistor connected between the input terminal of the amplifier and the grounding point, in parallel with the capacitor; and a diode connected in series with the resistor. The diode has a threshold voltage that is lower than the threshold voltage of the amplifying transistor.

Abstract: A power amplifier includes: an input terminal at which an input signal is input; a first amplifier element amplifying the input signal; a second amplifier element amplifying an output signal of the first amplifier element; an output terminal from which an output signal of the second amplifier element is output; a matching circuit connected between an output of the second amplifier element and the output terminal; a first switch connected between an output of the first amplifier element and an input of the second amplifier element; and a second switch having a first end connected to the output of the first amplifier element, and a second end. The matching circuit includes a first inductor and a first capacitor connected in series between the output of the second amplifier element and a grounding point. The second end of the second switch is connected to a connecting point of the first inductor to the first capacitor.

Abstract: A transistor includes: a semiconductor substrate; a first electrode on the semiconductor substrate and having first and second portions; a second electrode on the semiconductor substrate and spaced apart from the first electrode; a control electrode on the semiconductor substrate and disposed between the first electrode and the second electrode; and a first heat sink plate joined to the second portion of the first electrode without being joined to the first portion of the first electrode.

Abstract: A power amplifier includes an input terminal into which an input signal is input; a first amplification element amplifying the input signal; a second amplification element amplifying an output signal of the first amplification element; an output terminal from which an output signal of the second amplification element is output; a first matching circuit connected between an output of the second amplification element and the output terminal; a first switch connected between an output of the first amplification element and an input of the second amplification element; a second switch having a first end connected to the output of the first amplification element, and a second end; and a second matching circuit having a first end connected to the second end of the second switch, and a second end directly connected to the output of the second amplification element.

Abstract: A power amplifier includes: an input terminal at which an input signal is input; a first amplifier element amplifying the input signal; a second amplifier element amplifying an output signal of the first amplifier element; an output terminal from which an output signal of the second amplifier element is output; a matching circuit connected between an output of the second amplifier element and the output terminal; a first switch connected between an output of the first amplifier element and an input of the second amplifier element; and a second switch having a first end connected to the output of the first amplifier element, and a second end. The matching circuit includes a first inductor and a first capacitor connected in series between the output of the second amplifier element and a grounding point. The second end of the second switch is connected to a connecting point of the first inductor to the first capacitor.

Abstract: Amplification transistors respectively amplify an input signal. The output terminals of the amplification transistors are connected in series through respective transmission lines. A harmonic processing circuit is connected to an end of the array of collectors (output terminals) of the amplification transistors. The harmonic processing circuit suppresses harmonics included in output voltages of the amplification transistors. A transmission line and an MIM capacitor form a shorting circuit which establishes a short-circuit for the harmonics between the collector of the amplification transistor nearest to the harmonic processing circuit and the collector of the amplification transistor farthest from the harmonic processing circuit.

Abstract: Amplification transistors respectively amplify an input signal. The output terminals of the amplification transistors are connected in series through respective transmission lines. A harmonic processing circuit is connected to an end of the array of collectors (output terminals) of the amplification transistors. The harmonic processing circuit suppresses harmonics included in output voltages of the amplification transistors. A transmission line and an MIM capacitor form a shorting circuit which establishes a short-circuit for the harmonics between the collector of the amplification transistor nearest to the harmonic processing circuit and the collector of the amplification transistor farthest from the harmonic processing circuit.

Abstract: In a high-frequency power amplifier, gate feed portions are formed by dividing a gate feed which connects transistor gate electrodes in parallel, and each of the gate feed portions includes a given number of gate electrodes connected in parallel. Each of transistor cell elements includes a set of the gate electrodes connected in parallel. A resistance wire is interposed between the transistor cell elements to isolate each transistor cell element. The resistance wire and the gate electrodes are made of the same metal material and formed by the same process. Thus, closed loop oscillation of transistors is suppressed with no increase in chip size.

Abstract: A transistor cell is designed by combining a transistor with passive elements such as a resistor, a capacitor, and an inductor. The parameters of the passive elements are determined so that the transistor cell has a maximum available gain characteristic that is flat in a desired frequency range. Matching circuits for input/output impedance matching for the transistor cell are designed so that loss occurring in the matching circuits has a flat frequency characteristic. A semiconductor integrated circuit is designed by combining the transistor cell and the matching circuits thus designed.

Abstract: In a high-frequency power amplifier, gate feed portions are formed by dividing a gate feed which connects transistor gate electrodes in parallel, and each of the gate feed portions includes a given number of gate electrodes connected in parallel. Each of transistor cell elements includes a set of the gate electrodes connected in parallel. A resistance wire is interposed between the transistor cell elements to isolate each transistor cell element. The resistance wire and the gate electrodes are made of the same metal material and formed by the same process. Thus, closed loop oscillation of transistors is suppressed with no increase in chip size.

Abstract: A high-frequency circuit device includes a distribution circuit (16) for distributing a signal inputted from a signal input terminal (20) to a plurality of first lines (16b) through a branch portion (16a), a synthetic circuit (18) for combining signals inputted from a plurality of second lines (18b) into one through a combined portion (18a) as an output signal and outputting it from a signal output terminal (22), transistors (14) respectively placed between the first lines (16b) of the distribution circuit (16) and the second lines (18b) of the synthetic circuit (18), and Isolators (24) respectively connected between the transistors (14) and the signal input terminal (20) and between the transistors (14) and the signal output terminal (22).

Abstract: In order to stabilize a phase of an output signal of a transistor, a phase correction circuit includes: a) a circuit element connected in parallel to a gate of the transistor, an impedance including a reactance changing in response to a potential difference; and b) a voltage control circuit to decrease the reactance component in response to the increase in potential of the gate, wherein total reactance component of the circuit element and the transistor is maintained to a predetermined value. Because of the function of the phase correction circuit, another circuit using the output signal of the transistor can work correctly.

Abstract: In order to stabilize a phase of an output signal of a transistor, the phase correction circuit comprises: a) a circuit element connected in parallel to a gate of the transistor, an impedance including reactance component of the circuit element being changed by its potential difference; and b) a voltage control circuit to decrease the reactance component in response to the increase in potential of the gate, wherein a value of total reactance component of the circuit element and the transistor maintaining to the predetermined value. By the function of the phase correction circuit, another circuit using the output signal of the transistor can work correctly.

Abstract: It is intended to make it possible to design, easily without imposing undue load on a designer, a semiconductor integrated circuit that operates stably in a wide frequency range, to thereby provide a high-quality, low-cost semiconductor device capable of operating in a wide frequency range. A transistor cell is designed by combining a transistor with passive elements such as a resistor, a capacitor, and an inductor. The passive elements are so determined that the transistor cell has a maximum available gain characteristic that is flat in a desired frequency range. Matching circuits to serve for input/output impedance matching for the transistor cell are designed so that a loss occurring in the matching circuits has a flat frequency characteristic. A semiconductor integrated circuit is designed by combining the transistor cell and the matching circuits thus designed.

Abstract: A high-frequency circuit device includes a distribution circuit (16) for distributing a signal inputted from a signal input terminal (20) to a plurality of first lines (16b) through a branch portion (16a), a synthetic circuit (18) for combining signals inputted from a plurality of second lines (18b) into one through a combined portion (18a) as an output signal and outputting it from a signal output terminal (22), transistors (14) respectively placed between the first lines (16b) of the distribution circuit (16) and the second lines (18b) of the synthetic circuit (18), and Isolators (24) respectively connected between the transistors (14) and the signal input terminal (20) and between the transistors (14) and the signal output terminal (22).