| 摘要 |
PURPOSE:To improve a quick access and a write margin by providing two types of driver circuits and a changeover switch circuit for a potential supply means and individually driving a word line at a VDD level and at a boosting level. CONSTITUTION:In an initial status where drivers A, B and C individually supply a VSS potential, the potential of the word line and the charge amount of a boosting capacitor stand at zero. For driving the word line, a MOSFETQN1 is turned OFF, and a potential at the VDD level is supplied to the word line and the boosting capacitor through the use of the drives A and B. Since the QN1 is turned OFF in that state, different system drivers quickly drive the word line and charge a boosting capacitor D. After the boosting capacitor D is charged, the QN1 is turned ON, the VDD potential is supplied to the boositing capacitor from the drive C with the drivers A and B at a high impedance. Therefore the word line can be driven at the higher boosting level than the VDD level.
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