Semiconductor memory device employing an improved layout of sense

Abstract

A memory device according to the invention has a first pair of bit lines, having first and second bit lines, coupled to a first memory cell which cause a first potential difference between the first and second bit lines; a second pair of bit lines, having third and fourth bit lines, coupled to a second memory cell which causes a second potential difference between the third and fourth bit lines; a first sense amplifier having first and second transistors each of which is a first conductivity type, the gate electrode of said first transistor being connected to said first bit line, the first electrode of the first transistor being connected to the second bit line, the gate electrode of the second transistor being connected to the second bit line, the first electrode of the second transistor being connected to the first bit line; a second sense amplifier having third and fourth transistors each of which is the first conductivity type, the gate electrode of the third transistor being connected to the third bit line, the first electrode of the third transistor being connected to the fourth bit line, the gate electrode of the fourth transistor being connected to the fourth bit line, the first electrode of the fourth transistor being connected to the third bit line; and the second electrodes of said first, second, third and fourth transistors constituting a first common diffusion region formed in a first area of the major surface.