Abstract: A low-noise amplifier which is equipped with at least one redundancy circuit which is connected in parallel to an amplifying circuit, so that the low-noise amplifier operates without a significant signal loss even when an abnormality takes place in the amplifying circuit and the amplifying circuit is not replaced or troubleshooted. The low-noise amplifier includes a redundancy circuit (30) effectively operable instead of an amplifying circuit (24) when the amplifying circuit (24) is in an abnormal condition, and at least one switch (22) activates the redundancy circuit (30) when the amplifying circuit (24) is abnormal. In a preferred embodiment, the redundancy circuit (30) includes a transmission line (32) for bypassing an input RF signal when the amplifying circuit (24) is in an abnormal condition. In an alternative, the redundancy circuit (30) includes a redundant amplifying circuit (34), so that the redundant amplifying circuit (34) can amplify the input RF signal in place of the amplifying circuit (24).