| 摘要 |
PURPOSE: To perform stable refresh operation even if leakage is caused from a bias nodal point, in a DRAM having such constitution that a bias circuit is intermittently operated in a self refresh mode and a current is reduced. CONSTITUTION: When one shot signal appears in a refresh indicating signalϕ3 during a self refresh mode period. First, only a bias means activating signalϕA is made ENABLE, and a power supply group circuits are activated. Next, after a detecting circuit output signalϕB of substrate bias voltage is made NON-ENABLE, that is, after the substrate bias voltage reaches the prescribed value,ϕRAS being an internal RAS signal is generated and refresh is performed. Since substrate bias voltage at the time of refresh is surely made the prescribed value, a delay time of a delay circuit never be mismatch.
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