Sense amplifier

Abstract

A flip-flop type sense amplifier for a semiconductor memory device is disclosed, the sense amplifier comprising a pair of CMOS inverters cross-coupled with each other to form a CMOS flip-flop circuit having a pair of buffer circuits, for receiving the read-out voltage signals from multi-level memory cells and a predetermined reference voltage, respectively, and a pair of switching circuits for inverting a power source voltage across the flip-flop circuit through common sources of the flip-flop circuit, in response to the transition between a stand-by sequence and a latching operating. The common source of the p-channel transistors of the CMOS flip-flop circuit is connected to a negative potential source, and the common source of the n-channel transistors is connected to a positive potential source during a stand-by sequence, and vice versa, during a latching operation. This unique potential supply method enhances operational speed of the sense amplifier. In a multi-level memory device, a plurality of the sense amplifiers are connected in parallel for the discrimination of the read-out signals changing in a range of a few volts.