Patent ID: 8149049

Claim:
A low noise receiving apparatus comprising: an amplifier which amplifies a received input signal; an output matching circuit connected between the amplifier and an output terminal which matches an impedance of an output side of the amplifier; a bypass circuit which bypasses the amplifier and has an output connected to an output side of the output matching circuit; and a switching circuit which switches whether or not to connect an output of the amplifier to an alternating current ground, the switching circuit having one end connected between the amplifier and the output matching circuit and another end connected to the alternating current ground; wherein the low noise receiving apparatus has an amplification mode in which the input signal is output to the output terminal via the amplifier and a bypass mode in which the amplifier is bypassed to output the input signal to the output terminal via the bypass circuit, in the amplification mode, the switch circuit separates the output of the amplifier from the alternating current ground so that an impedance of the output side of the amplifier is matched by the output matching circuit, and in the bypass mode, the switching circuit connects the output of the amplifier to the alternating current ground so that an impedance of the output matching circuit viewed from the output terminal side becomes lower than in the amplification mode.