Reference setting circuit for determining written-in content in nonvolatile semiconductor memories

摘要

A nonvolatile semiconductor memory according to this invention is so constructed that different data readout references are used in an ordinary readout mode and in a program verification mode. The different read-out references can be set by changing reference input potential VREF supplied to a differential sense amplifier for amplifying a potential derived onto a bit line from a memory cell, or by changing an input threshold level of a circuit for sensing the potential on the bit line. In this case, the readout reference in the program verification mode is set severe, or high, in comparison with that in the ordinary readout mode.