| 摘要 |
A substrate back bias voltage generator of a dynamic type RAM is provided with a first voltage generator having a relatively large current supply capacity, a second voltage generator having a relatively small current supply capacity, and a substrate back bias voltage detecting circuit for controlling operation of the first voltage generator. For example, when the dynamic type RAM is in a &upbar& C before &upbar& R refresh mode, the operation of the first voltage generator is limited selectively, and the operation of the second voltage generator and the substrate back bias voltage detecting circuit is stopped selectively.
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