Semiconductor integrated circuit device equipped with substrate biasing system selectively powered from internal and external power sources
AssigneeNEC Corporation
InventorsTadahiko Sugibayashi, Yasuji Koshikawa, Takahiro Hara
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Abstract
A dynamic random access memory device negatively biases the semiconductor substrate, and a substrate bias system incorporated therein produces a negative bias voltage from an external power voltage level for accelerating the negative biassing operation before an internal power voltage is sufficiently developed by an internal step-down circuit incorporated therein; however, after the development, the substrate bias system produces the negative bias voltage from the internal power voltage so as to be less affectable by fluctuation of the external power voltage level.
Claims12
A semiconductor integrated circuit device fabricated on a semiconductor substrate, comprising:
- a) an internal circuit;
- b) a power supply system having a means for distributing an external power voltage supplied from the outside of said semiconductor integrated circuit device, and an internal step-down circuit operative to produce an internal power voltage from said external power voltage and to regulate said internal power voltage to a predetermined reference level internally produced;
- and
- c) a substrate bias system operative to bias said semiconductor substrate to a certain level with a bias voltage, and having a first bias voltage producing circuit for producing said bias voltage from said external power voltage and a second bias voltage producing circuit for producing said bias voltage from said internal power voltage, and first bias voltage producing circuit being activated before said internal power voltage level reaches said predetermined reference level.
Dependencies are inferred from the claim text.