LOW-NOISE SIGNAL AMPLIFYING CIRCUIT AND METHOD THEREOF

摘要

A signal amplifying circuit includes: a first transistor having a first connecting terminal coupled to an input signal, and a controlling terminal coupled to a first reference voltage; an adjustable resistive circuit having a first terminal coupled to a second connecting terminal of the first transistor; and a second transistor having a first connecting terminal coupled to a second terminal of the adjustable resistive circuit, a controlling terminal coupled to a second reference voltage, and a second connecting terminal for outputting an output signal corresponding to the input signal; wherein a resistance of the adjustable resistive circuit is adjusted to make an input impedance looking into the first transistor from the first connecting terminal equal a predetermined impedance.