Abstract: A concurrent-type multiband amplifier (or a dual-band amplifier) which amplifies multiband signals concurrently using a plurality of (N) amplifier circuits which each independently amplify signals in a plurality of (N) frequency bands. An n-th (n=any of 1 to N) amplifier circuit is provided with a circuit for blocking signals in frequency bands other than the n-th frequency band so as to amplify and output only the n-th frequency band signal. The n-th amplifier circuit is designed so as to consist of its input/output impedance matching circuit for the n-th an amplifier element at the n-th frequency band.

Abstract: A concurrent-type multiband amplifier (or a dual-band amplifier) which amplifies multiband signals concurrently using a plurality of (N) amplifier circuits which each independently amplify signals in a plurality of (N) frequency bands. An n-th (n=any of 1 to N) amplifier circuit is provided with a circuit for blocking signals in frequency bands other than the n-th frequency band so as to amplify and output only the n-th frequency band signal. The n-th amplifier circuit is designed so as to consist of its input/output impedance matching circuit for the n-th an amplifier element at the n-th frequency band.

Abstract: An amplifier circuit operating at a fundamental angular frequency •0, includes: a transistor which is represented by an equivalent circuit which includes: an equivalent output current source, a drain-source capacitor as a parallel parasitic capacitor to an output node of the equivalent output current source, and a drain inductor as serial parasitic inductor connected between the equivalent output current source and a drain output node; a harmonic frequency processing circuit which includes an input node connected with the drain output node and an output node; a resonant circuit section provided between the output node of the harmonic frequency processing circuit and a ground node and comprising (2n+1) resonators which have resonance frequencies different from each other; and a load resistance provided in a back stage of the harmonic frequency processing circuit.

Abstract: An amplifier circuit operating at a fundamental angular frequency •0, includes: a transistor which is represented by an equivalent circuit which includes: an equivalent output current source, a drain-source capacitor as a parallel parasitic capacitor to an output node of the equivalent output current source, and a drain inductor as serial parasitic inductor connected between the equivalent output current source and a drain output node; a harmonic frequency processing circuit which includes an input node connected with the drain output node and an output node; a resonant circuit section provided between the output node of the harmonic frequency processing circuit and a ground node and comprising (2n+1) resonators which have resonance frequencies different from each other; and a load resistance provided in a back stage of the harmonic frequency processing circuit.

Abstract: By simultaneously supplying input and output terminals of a microwave transistor with input and incident signals from a divided (branched) microwave signal, equivalent load-pull characterization is carried out without using an output impedance tuner. The amplitude and phase of the incident signal may be varied to equivalently vary the admittance or impedance looking into the output terminals on the entire admittance or impedance plane.