US Patent 7505311 Semiconductor memory device

A semiconductor memory device includes a memory cell array with electrically rewritable and non-volatile memory cells arranged therein, and a bit line control circuit connected to a bit line of the memory cell array to control and detect the bit line voltage in accordance with operation modes, wherein the bit line control circuit comprises a first transistor and a second transistor with a breakdown voltage higher than that of the first transistor, the second transistor being disposed between the first transistor and a bit line in the memory cell array to be serially connected to the first transistor, and wherein a connection node between the first and second transistors is fixed in potential at a data erase time.