| 摘要 |
PURPOSE: To execute a refresh operation corresponding to an element temperature by sensing the charging voltage of a reference memory cell and generating a refresh request signal only when that voltage becomes lower than a reference. CONSTITUTION: A structural leaked current exists at a capacitor 2 of a reference memory cell 51, the capacitor 2 is discharged by this leaked current, and a voltage Vs is gradually decreased. Then, the resistance of a transistor 4 of a voltage sensor 52 is increased, a voltage Vd of an output node 6 is gradually decreased corresponding to the voltage Vs as a well and when the voltage Vd becomes lower than a reference voltage Vref , a voltage Vc of an output node 12 of a comparator 53 is turned to low level. This voltage Vc turns on a transistor 13 of an output terminal 54 and turns off a transistor 14, a voltage Vcc of an output node 15 is turned to high level, and a refresh request signalϕrrs is outputted.
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