A sense amplifier comprises a sense node, a reference node, a memory input stage circuit, a reference input stage circuit, an output stage circuit, and a shielding circuit. The memory input stage circuit comprises first input node for maintaining a first sense voltage established by a cell current and establishes a second sense voltage on the sense node in response to the first sense voltage. The reference input stage circuit comprises an output node and a second input node, which is for maintaining a first reference voltage established by the reference current and establishes a second reference voltage on the reference node in response to the first reference voltage. The output stage circuit obtains a sense result in response to the second reference voltage and the second sense voltage. The first shielding circuit shields the output node from being interfered with the second reference voltage on the reference node.