SEMICONDUCTOR DEVICE

摘要

PURPOSE:To make it possible to increase the time unit redundant signal reverses against stored charge reduction of FAMOS transistor by forming power electronic switch with P-channel type and N-channel type MOS transistors to lower electric potential at reading by a certain amount less than external applied reading voltage. CONSTITUTION:At reading, the level of external applied power source 1 for writing is made the same as that of external applied power source 2 for reading and control signal 3 is made 'H' level thus making a P-type MOS transistor 4 nonconductive and an N-type MOS transistor 5 conductive. Since the drain and the gate electric potential are at the same level, lease output potential is lower than the gate potential by threshold voltage of the transistor. Therefore, the level of gate potential of FAMOS transistor 7 at reading is lower than the potential of external power source 2 for reading by threshold voltage of the N-type MOS transistor 5. The drain of the FAMOS transistor 7 is connected to a reading control circuit 9. When the FAMOS transistor 7 is written, it becomes nonconductive when reading gate potential is applied and redundant signal 10 becomes 'H' level.