semiconductor memory device of enhancing bitline precharge time

PURPOSE: A semiconductor memory device is provided to minimize or shorten a bit line precharge time, and to achieve a high speed operation by controlling an isolation transistor more efficiently. CONSTITUTION: According to the semiconductor memory device, an isolation part connects or isolates electrically a memory cell and a sense amp connected through a bit line pair, and an equalization part precharges the bit line pair connected to the memory cell to an equal voltage level during a precharge mode. And an isolation control part applies a driving control signal to drive the isolation part during the precharge mode as an internal power supply voltage level lower than a high voltage level, after a constant time period from the start of a precharge operation of the equalization part.