A sensing-amplifier device includes a first input terminal, a second input terminal, a reference unit, and a sense amplifier. The reference unit is configured to provide a reference signal. The switching unit is selectively coupled to the first input terminal, the second input terminal, and a reference unit. The sense amplifier includes two terminals. The two terminals of the sense amplifier are coupled to the first input terminal and the second input terminal respectively by switching of the switching unit so as to operate in a twin memory unit mode, or one terminal of the sense amplifier is coupled to the first input terminal or the second input terminal and the other terminal of the sense amplifier is coupled to the reference unit by switching of the switching unit so as to operate in a single memory unit mode.