Patent ID: 7541894

Claim:
A phase-shifting circuit comprising: an input terminal of a high frequency signal; an output terminal of the high frequency signal; a first parallel circuit which is connected across said input terminal and said output terminal, which is composed of a first inductor and a first switching element that exhibits a through state or resistive property in an ON state and a capacitive property in an OFF state, and which produces parallel resonance at a prescribed frequency when said first switching element is in the OFF state; a series circuit which is connected in parallel with said first parallel circuit, and which is composed of a second inductor and a third inductor that have a reactance sufficiently larger than a resistance of said first switching element in the ON state; a capacitor having its first terminal connected to a point of connection of said second inductor and said third inductor; a second parallel circuit which is connected across a second terminal of said capacitor and a ground, which is composed of a fourth inductor and a second switching element that exhibits a through state or resistive property in an ON state and a capacitive property in an OFF state, and which produces parallel resonance at a prescribed frequency when said second switching element is in the OFF state; and applying means of control signals for establishing a first operation mode and a second operation mode by switching between them, said first operation mode setting said first switching element at the ON state and said second switching element at the OFF state, and said second operation mode setting said first switching element at the OFF state and said second switching element at the ON state.