US Patent 7474556 Phase-change random access memory device

A phase-change random access memory device is provided. The phase-change random access memory device includes a plurality of memory blocks, a main word line, a plurality of local word lines and a plurality of section word line drivers connected between the main word line and each of the plurality of local word lines and adapted to adjusting voltage levels of the plurality of local word lines in response of voltages applied to the main word line and block information. The plurality of section word line drivers include at least one first section word line driver and at least one second section word line driver. The first section word line drivers include pull-down devices while not including pull-up devices.