Sense amplifier for semiconductor memory device

Abstract

A direct sense amplifier of the present invention incorporates and isolates: an MOS transistor serving as a differential pair and having a gate connected to a bit line; and an MOS transistor controlled by a column select line wired between RLIO lines in a bit-line direction, and further connects a source of the MOS transistor serving as the differential pair to a common source line wired in the word-line direction. Since the direct sense amplifier only in a select map is activated by the column select line and the common source line during an read operation, power consumption is significantly reduced during the read operation. Also, since a parasitic capacitance of the MOS transistor serving as the differential pair is separated from the local IO line, a load capacity of the local IO line is reduced and the read operation is speeded up. In addition, during the read operation, a data pattern dependency of the load capacity of the local IO line is reduced and a post-manufacture test is easily made.