Abstract: A high frequency power amplifier comprises: a multi-finger transistor with transistor cells electrically connected in parallel; an input side matching circuit connected to gate electrodes of the transistor cells; and resonant circuits respectively connected between the gate electrode of a transistor cell and the input side matching circuit. The resonant circuit resonates at a second harmonic of the operating frequency of the transistor or within a predetermined range of frequencies having a center at the second harmonic of the operating frequency, and becomes a high-impedance load at the second harmonic, or an open load.

Abstract: A high frequency power amplifier comprises: a multi-finger transistor with transistor cells electrically connected in parallel; an input side matching circuit connected to gate electrodes of the transistor cells; and resonant circuits respectively connected between the gate electrode of a transistor cell and the input side matching circuit. The resonant circuit resonates at a second harmonic of the operating frequency of the transistor or within a predetermined range of frequencies having a center at the second harmonic of the operating frequency, and becomes a high-impedance load at the second harmonic, or an open load.

Abstract: A high-frequency power amplifier has an FET element having a unit FETs in multifinger form, and having a gate pad through which a signal is input, a source pad that is grounded, and a drain pad through which a signal is output. A high-frequency processing circuit includes series resonance circuits shunt-connected between the gate pads of the unit FETs and grounding ends. Two of the series resonance circuits have respective different resonance frequencies which correspond to second and higher harmonics of a frequency included in the operating frequency band of the FET element.

Abstract: At least one of wiring areas divided by substrate dividing slits includes a region on which none of the strip conductors is located, the region having a U-shape as viewed in plan and enclosing one of the strip conductors on three sides. The length of the enclosed strip conductor is set such that, at a harmonic of a fundamental frequency, the strip line, including the enclosed strip conductor, exhibits very low impedance and acts as a short circuit. The length of the enclosed strip conductor may be set substantially equal to 1/(4n) times the wavelength corresponding to a fundamental frequency, to short circuit the nth harmonic, where n is an integer. Both ends of the U-shaped region are preferably disposed on the side of the surface of the matching circuit substrate closest to a transistor.

Abstract: A high-frequency power amplifier has an FET element having a unit FETs in multifinger form, and having a gate pad through which a signal is input, a source pad that is grounded, and a drain pad through which a signal is output. A high-frequency processing circuit includes series resonance circuits shunt-connected between the gate pads of the unit FETs and grounding ends. Two of the series resonance circuits have respective different resonance frequencies which correspond to second and higher harmonics of a frequency included in the operating frequency band of the FET element.

Abstract: A high frequency power amplifier includes: a multi-finger transistor including transistor cells electrically connected in parallel; an input side matching circuit connected to gate electrodes of the transistor cells; and resonant circuits, each resonant circuit being connected between a gate electrode of a respective one of the transistor cells and the input side matching circuit. The resonant circuits resonate at a second harmonic of the operational frequency of the transistor or at a frequency within a predetermined range centered at the second harmonic and act as a short circuit or exhibit low impedance as seen from the gate electrode.

Abstract: In a power amplifier a Doherty amplifier is provided with an output higher harmonic reflection circuit that is connected to the output terminal of a first FET chip and sets an even-numbered higher harmonic load of an output signal at the output terminal to be a short-circuit, or at a low impedance approximating a short-circuit, and sets an odd-numbered higher harmonic load of an output signal at the output terminal to be an open-circuit, or a high impedance approximating an open-circuit.

Abstract: A high frequency power amplifier includes: a multi-finger transistor including transistor cells electrically connected in parallel; an input side matching circuit connected to gate electrodes of the transistor cells; and resonant circuits, each resonant circuit being connected between a gate electrode of a respective one of the transistor cells and the input side matching circuit. The resonant circuits resonate at a second harmonic of the operational frequency of the transistor or at a frequency within a predetermined range centered at the second harmonic and act as a short circuit or exhibit low impedance as seen from the gate electrode.

Abstract: At least one of wiring areas divided by substrate dividing slits includes a region on which none of the strip conductors is located, the region having a U-shape as viewed in plan and enclosing one of the strip conductors on three sides. The length of the enclosed strip conductor is set such that, at a harmonic of a fundamental frequency, the strip line, including the enclosed strip conductor, exhibits very low impedance and acts as a short circuit. The length of the enclosed strip conductor may be set substantially equal to 1/(4n) times the wavelength corresponding to a fundamental frequency, to short circuit the nth harmonic, where n is an integer. Both ends of the U-shaped region are preferably disposed on the side of the surface of the matching circuit substrate closest to a transistor.

Abstract: In a power amplifier a Doherty amplifier is provided with an output higher harmonic reflection circuit that is connected to the output terminal of a first FET chip and sets an even-numbered higher harmonic load of an output signal at the output terminal to be a short-circuit, or at a low impedance approximating a short-circuit, and sets an odd-numbered higher harmonic load of an output signal at the output terminal to be an open-circuit, or a high impedance approximating an open-circuit.

Abstract: A high power semiconductor device including gate electrodes also includes an active region of an approximately rectangular shape, located on a semiconductor substrate; a drain electrode located on the active region; and first and second source electrodes which are disposed on opposite sides to the drain electrode so that the first and second source electrodes face each other across at least some of the gate electrodes. The directions of currents carried by the first and second source electrodes are opposite to each other.

Abstract: A power amplifier includes a first amplifier acting as an inverse Class F amplifier and having a first transistor and a first two-tenuinal network, a second amplifier acting as a Class F amplifier and having a second transistor and a second two-terminal network, a power distribution circuit for distributing an input signal to the first transistor and the second transistor such that a phase difference between signals supplied to the first transistor and the second transistor reaches about 90 degrees, a distributed line for controlling an output load of the first transistor through an impedance transformation based on an operating state of the second transistor, and a bias circuit for biasing the first transistor and the second transistor such that different harmonic processing conditions are set in the first amplifier and the second amplifier.

Abstract: A high power semiconductor device including gate electrodes also includes an active region of an approximately rectangular shape, located on a semiconductor substrate; a drain electrode located on the active region; and first and second source electrodes which are disposed on opposite sides to the drain electrode so that the first and second source electrodes face each other across at least some of the gate electrodes. The directions of currents carried by the first and second source electrodes are opposite to each other.

Abstract: A high frequency power amplifier that can improve efficiency of an operation of a transistor without limiting any input-side higher harmonic load of an impedance matching circuit to a short-circuit load, and can increase reflection of higher harmonics. By adjusting line lengths and line widths of signal lines, a 2nd harmonic can be adjusted to be an open load (a reflected phase angle of &Ggr;in: 0-90°, the quantity of reflection: 0.6-1.0), and a 3rd harmonic is adjusted to be a short-circuit load (the reflected phase angle of &Ggr;in: 110-270°, the quantity of reflection: 0.6-1.0). With this input-side higher harmonic load of the impedance matching circuit, efficiency of transistor operation can be improved. By disposing a higher harmonic processing circuit closer to a transistor, a high frequency power amplifier with a shortened line length between the higher harmonic processing circuit and the transistor, and increased quantity of reflection of higher harmonics is produced.

Abstract: A high-frequency power amplifier includes a first amplifier acting as an inverse Class F amplifier and having a first transistor and a first two-terminal network, a second amplifier acting as a Class F amplifier and having a second transistor and a second two-terminal network, a power distribution circuit for distributing an input signal to the first transistor and the second transistor such that a phase difference between the first transistor and the second transistor reaches about 90 degrees, a distributed line for controlling an output load of the first transistor through impedance transformation based on an operating state of the second transistor and a bias circuit provided for the first transistor and the second transistor such that different harmonic processing conditions are set in the first amplifier and the second amplifier.

Abstract: A high frequency power amplifier that can improve an efficiency of an operation of a transistor without limiting any input-side higher harmonic load of an impedance matching circuit to a short-circuit load, and can increase a quantity of reflection of higher harmonics. By adjusting line lengths L1 to L5 and line widths W1 to W5 of the signal lines 1 to 5, a 2nd higher harmonic can be adjusted to be an open load (a reflected phase angle of &Ggr;in: 0-90°, the quantity of reflection: 0.6-1.0), and a 3rd higher harmonic is adjusted to be a short-circuit load (the reflected phase angle of &Ggr;in:110-270°, the quantity of reflection: 0.6-1.0). By this optimization of an input-side higher harmonic load of the impedance matching circuit, an efficiency of transistor operation can be improved.

Abstract: A semiconductor amplifier circuit receiving a high frequency signal and amplifying and outputting the signal includes a transistor for receiving the high frequency signal; and a waveform control connected to an input terminal of the transistor and controlling a negative value of the high frequency signal to be less than the gate breakdown voltage of the transistor and not below a negative threshold voltage. Therefore, a low distortion characteristic is available even when a transistor with a large magnitude of the gate breakdown voltage is manufactured. As a result, accuracy in controlling the value of the gate breakdown voltage during manufacturing is not required to be as high as in conventional manufacturing, resulting in a lower processing cost as well as improved yield.