To provide a low noise amplifier and a radio communication device that can obtain a stable reception performance without causing an input impedance to change even if gain is switched.
A reception side low noise amplifier 20 comprises: an amplifying unit 201 comprising a gain switching function; an impedance element 202 with which the input impedance of the low noise amplifier 20 when the amplifying unit 201 is set to a low gain matches the input impedance when the amplifying unit 201 is set to a high gain; and a switch 203 which connects/disconnects the impedance element 202 to/from the input terminal of the amplifying unit 201. When the amplifying unit 201 is set to the low gain, the impedance element 202 is connected to the input terminal of the amplifying unit 201. This allows the input impedance of the low noise amplifier 20 to be kept constant even if the gain of the amplifying unit 201 is switched.
Ryuichiro Mori
Naoki Matsuo