| 摘要 |
PURPOSE:To improve the reliability by detecting a change with lapse of time of a threshold value of an MOS type nonvolatile memory transistor so as to grasp completely a memory storage characteristics. CONSTITUTION:A voltage turning on an MOSFET5 and turning off an MOSFET 3 is applied to its gate by adjusting a resistor 2 and an impedance of the MOSFET5 so that a voltage of a memory readout constant voltage source 1 is not applied to the gate of an MOS nonvolatile memory FET4 from the source of the MOSFET3 and applying a voltage to an input section VIN1 at the same time as the application of voltage to an input section VUN2. Then, a threshold value of the FET4 changed with lapse of time is detected accurately by giving optionally the gate voltage of the FET4 externally. |
