A circuit includes a first amplifying stage, a noise extraction circuit and a noise cancellation circuit. The first amplifying stage is arranged for receiving an input signal to generate an amplified input signal. The noise extraction circuit is coupled to the first amplifying stage, and is arranged for receiving at least the amplified input signal to generate a noise signal associated with noise components of the amplified input signal. The noise cancellation circuit is coupled to the first amplifying stage and the noise extraction circuit, and is arranged for cancelling noise components of the amplified input signal by using the noise signal generated by the noise extraction circuit, to generate a noise-cancelled amplified input signal.