An amplifier, comprising: a plurality of amplification stages (Amp1, Amp2,...AmpN), cascaded between an input terminal and an output terminal of the amplifier, wherein an output stage (AmpN) among the plurality of amplification stages is switched between a normal mode and an attenuation mode; a controller, operable to switch the output stage from the normal mode to the attenuation mode in response to an amplifier input signal at the input terminal being lower than a threshold; a feedback circuit formed by: a first feedback resistor and a first switch, connected in series; and a second feedback resistor and a second switch, connected in series, wherein the amplifier is so configured that: when the output stage (AmpN) is in the normal mode, the first switch is closed and the second switch is open, and the output terminal of the amplifier is coupled to an input stage among the plurality of amplification stages via the first feedback resistor; in the attenuation mode, the output stage (AmpN) provides an attenuation resistor coupled in series with a load resistor of the amplifier; and when the output stage (AmpN) is in the attenuation mode, the second switch is closed and the first switch is open, and a first terminal of the attenuation resistor is coupled to the input stage via the second feedback resistor while a second terminal of the attenuation resistor is coupled to the load resistor. a plurality of amplification stages (Amp1, Amp2,...AmpN), cascaded between an input terminal and an output terminal of the amplifier, wherein an output stage (AmpN) among the plurality of amplification stages is switched between a normal mode and an attenuation mode; a controller, operable to switch the output stage from the normal mode to the attenuation mode in response to an amplifier input signal at the input terminal being lower than a threshold; a feedback circuit formed by: a first feedback resistor and a first switch, connected in series; and a second feedback resistor and a second switch, connected in series, wherein the amplifier is so configured that: when the output stage (AmpN) is in the normal mode, the first switch is closed and the second switch is open, and the output terminal of the amplifier is coupled to an input stage among the plurality of amplification stages via the first feedback resistor; in the attenuation mode, the output stage (AmpN) provides an attenuation resistor coupled in series with a load resistor of the amplifier; and when the output stage (AmpN) is in the attenuation mode, the second switch is closed and the first switch is open, and a first terminal of the attenuation resistor is coupled to the input stage via the second feedback resistor while a second terminal of the attenuation resistor is coupled to the load resistor. a first feedback resistor and a first switch, connected in series; and a second feedback resistor and a second switch, connected in series, wherein the amplifier is so configured that: when the output stage (AmpN) is in the normal mode, the first switch is closed and the second switch is open, and the output terminal of the amplifier is coupled to an input stage among the plurality of amplification stages via the first feedback resistor; in the attenuation mode, the output stage (AmpN) provides an attenuation resistor coupled in series with a load resistor of the amplifier; and when the output stage (AmpN) is in the attenuation mode, the second switch is closed and the first switch is open, and a first terminal of the attenuation resistor is coupled to the input stage via the second feedback resistor while a second terminal of the attenuation resistor is coupled to the load resistor. when the output stage (AmpN) is in the normal mode, the first switch is closed and the second switch is open, and the output terminal of the amplifier is coupled to an input stage among the plurality of amplification stages via the first feedback resistor; in the attenuation mode, the output stage (AmpN) provides an attenuation resistor coupled in series with a load resistor of the amplifier; and when the output stage (AmpN) is in the attenuation mode, the second switch is closed and the first switch is open, and a first terminal of the attenuation resistor is coupled to the input stage via the second feedback resistor while a second terminal of the attenuation resistor is coupled to the load resistor.