Amplifier circuit
View Patent ↗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. The resonance frequencies of the (2n+1) resonators are coincident with frequencies of (n+1) poles and n zeros formed between the drain output node and the ground node in the transistor when the output node of the harmonic frequency processing circuit is short-circuited to the ground node.
1. An amplifier circuit operating at a fundamental angular frequency ω 0 , comprising:
a transistor which is represented by an equivalent circuit which comprises:
an equivalent output current source;
a drain-source capacitor as a parallel parasitic capacitor to an output node of said equivalent output current source; and
a drain inductor as serial parasitic inductor connected between said equivalent output current source and a drain output node;
a harmonic frequency processing circuit which comprises:
an input node connected with said drain output node;
an output node;
a ladder circuit of n (n=1, 2, 3, . . . ) stages provided between said input node and said output node, wherein each of said n stages comprises a parallel capacitor and a serial inductor;
a resonant circuit section provided between the output node of said harmonic frequency processing circuit and a ground node and comprising (2n+1) resonators which have resonance frequencies different from each other; and
a load resistor provided in a back stage of said harmonic frequency processing circuit,
wherein the resonance frequencies of said (2n+1) resonators correspond with frequencies of (n+1) poles and n zeros formed between said drain output node and said ground node in said transistor when said output node of said harmonic frequency processing circuit is short-circuited to said ground node, and
wherein the resonant frequencies of 2n resonators of said (2n+1) resonators coincident correspond with a frequency (2ω 0 ) of second harmonic wave to a frequency of (2n+1) th harmonic wave ((2+1)ω 0 ), respectively.
2. The amplifier circuit according to claim 1 , wherein said (2n+1) resonators comprises a capacitor and an inductor which are connected in series,
wherein said (2n+1) resonators are short-circuited in the frequencies of the (n+1) poles and the n zeros formed between said output node of said equivalent output current source and said ground node, when said output node of said harmonic frequency processing circuit is short-circuited.
3. The amplifier circuit according to claim 1 , wherein said resonant circuit section comprises as said (2n+1) resonators, (2n+1) tip-opened stubs having ¼ of wavelengths of said resonance frequencies and short-circuited in the frequencies of the (n+1) poles and the n zeros formed between said output node of said equivalent output current source and said ground node, when said output node of said harmonic frequency processing circuit is short-circuited.
4. The amplifier circuit according to claim 1 , further comprising:
a matching circuit provided between a back stage of said harmonic frequency processing circuit and a front stage of said load resistor and corresponding to the fundamental angular frequency ω 0 .