A sense amplifier includes a sensing circuit and an equalizing circuit. The sensing circuit is configured to supply one or more output signals according to one or more input signals. The equalizing circuit is configured to bring the sensing circuit to a metastable state from which the sensing circuit switches to an inverting state in response to a potential of the one or more input signals. Each transistor in the sensing circuit may switch to logic 0 or logic 1 faster and die-to-die PVT variations may be compensated, thereby providing high speed and low offset read operation.