| 摘要 |
<p>PURPOSE:To select whether or not large stress is given on the tunnel oxide film of a memory transistor at need, by changing a time constant by selecting a capacitor which decides the time constant of the change of a reference voltage in a voltage control circuit out of plural capacitors. CONSTITUTION:The voltage control circuit which changes the output of a high voltage generation circuit 20 following after the reference voltage is provided, and plural capacitors C3 and C5 which decide the time constant of the change of the reference voltages are provided. And since it is possible to change the time constant by selecting the capacitors C3 and C5 appropriately out of the plural capacitors, it is possible to shape the output waveform of the high voltage generation circuit that changes following after the reference voltage at need. For example, the comparatively large leading time constant of the reference voltage to be inputted to the negative input part of a comparator 21 is decided by the synthetic capacity of the capacitors C3 and C5 in an ordinary operation, and at the time of testing a memory cell, a transistor T3 is de-energized, and the comparatively small leading time constant of the reference voltage to be inputted to the negative input part of the comparator 21 is decided.</p> |
