Patent ID: 7002866

Claim:
A sense amplifier circuit for amplifying a voltage difference between a pair of complementary bit lines of a semiconductor memory device, the sense amplifier comprising: a first transistor, formed in an active region, having a first gate disposed straight along a bit line direction, a first drain coupled to a first bit line, and a common source; and a second transistor, formed in the active region, having a second gate disposed in parallel to the first gate, a second drain coupled to a second bit line, and the common source shared with the first transistor, wherein the first gate is coupled to the second drain and the second gate is coupled to the first drain to form a latch circuit, and wherein each of the first and the second gates have a first portion, at a first edge of the active region, having a first gate length along a perpendicular direction that is perpendicular to the bit line direction, a second portion, at a second edge opposing the first edge, having the first gate length along the perpendicular direction, and a third portion, between the first and second portions, having a second gate length along the perpendicular direction, the first gate length being longer than the second gate length.