NONVOLATILE SEMICONDUCTOR MEMORY

摘要

PROBLEM TO BE SOLVED: To speed up reading and prevent wrong reading by carrying out a precharge control by two systems to make different a precharge term of a read line group and a precharge term of a reference cell group. SOLUTION: In selecting a read cell of a first cell array part and a reference cell of a second cell array part, a precharge control circuit 600 makes a precharge signal PR(2) bar overlap with a precharge signal PR(1) bar and surely increases a charge quantity of the second cell array part. On the contrary, in selecting a read cell of the second cell array part and a reference cell of the first cell array part, the precharge control circuit 600 makes the precharge signal PR(1) bar overlap with the precharge signal PR(2) bar. When a precharge control is carried out 111 two systems, the precharge signal at the side of the reference cell is always overlapped to the precharge signal at the side of the read cell.