A sense amplifier comprises a cell current generator, a reference current generator, a first and a second charge/discharge elements, a first and a second voltage trigger circuits, and a data holder. The cell current generator is used to output a cell current of a memory cell. The reference current generator is used to output a duplicated reference current. The first and the second charge/discharge elements are used to convert the cell current and the duplicated reference current to voltage signals respectively. The first voltage trigger circuit is used to output a data signal according to a voltage signal outputted from the first charge/discharge element. The second voltage trigger circuit is used to output a hold control signal according to a voltage signal outputted from the second charge/discharge element. The data holder is used to hold a voltage level of the data signal according to the hold control signal.