| 摘要 |
PURPOSE:To prevent an unsatisfactory writing of a data to a memory cell by reducing a leak current during cutting off of a polysilicon type MOSFET. CONSTITUTION:In a writing circuit WD, when either one of an input signal (a) or di is low level, a node n1 of a pre-stage gate circuit G1 is charged up to an electric potential such as 12.5V near to a writing voltage Vpp through a depression type MOSFETQd. Therefore, a voltage between a gate and a source of a next stage polysilicon type MOSFETQp receiving the electric potential of the node n1 to a gate terminal goes to below 5V to obtain a complete cutting off condition. As a result, the leak current of the MOSFETQp is lowered to about 1/100, so that a level lowering of a high voltage Vpp1 is scarcely produced. Thereby, a generation a writing failure of a data to a memory cell is prevented. |
