NONVOLATILE SEMICONDUCTOR STORAGE DEVICE

摘要

PURPOSE:To increase the read margin of a nonvolatile semiconductor storage device by specifying a comparison potential for detecting data. CONSTITUTION:A potential equivalent to a potential impressed to a row line driving selectively a memory element is impressed to a control gate of a dual gate transistor (TR)Mc the same as a memory element of one potential generating circuit 30 of a comparison potential generating circuit 20. Thus, a potential VBc of an output point Bc of the circuit 30 becomes a value coresponding to ''0'' of the storage content of the memory element to be changed with a power supply voltage Vc. A control gate of a TRMd being the same as the TRMc of the other similar potential generating circuit 40 of the circut 20 is connected to a bias generating circuit 50, the potential at an output point Bd is changed similarly together with the power supply voltage, the inclination is changed and reaches a potential VBd corresponding to ''1'' of the storage content of the memory element. A coupling point D between the circuits 30 and 40 becomes an intermediate potential VD of the potentials VBd and VBc and this potential is applied to a sense amplifier as a comared potential. Thus, the read margin is increased independently of the power supply potential.