Local bit select circuit with slow read recovery scheme
First Claim
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1. A domino SRAM comprising in combination:
- a local bit line amplifier connected across a local bit line pair;
a transistor switch coupled to said amplifier, said switch in one state rendering said amplifier operative to amplify a voltage difference between said local bit line pair and in another state rendering said amplifier dormant;
means to place said switch in said one state during a read operation if a cell serviced by said local bit line pair has been determined to be a slow to read cell.
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Abstract
Local bit line pairs in a domino SRAM include an amplifier to amplify the voltage differential across the bit lines during a read operation if a cell in the local group of cells has been identified as a slow to read cell. The amplifier includes a transistor switch that is turned on by a timing pulse during the read operation, but only if the Array Built In Self-Test (ABIST) has detected a slow to read cell in the local group. If there is no slow cell, the amplifier is not activated, and the domino read operation is carried out. The amplifier can be used globally across the SRAM or selectively in certain sub-arrays.
43 Citations
20 Claims
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1. A domino SRAM comprising in combination:
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a local bit line amplifier connected across a local bit line pair; a transistor switch coupled to said amplifier, said switch in one state rendering said amplifier operative to amplify a voltage difference between said local bit line pair and in another state rendering said amplifier dormant; means to place said switch in said one state during a read operation if a cell serviced by said local bit line pair has been determined to be a slow to read cell. - View Dependent Claims (3, 4, 5, 6, 7, 8)
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2. A method for operating a domino SRAM including the steps of:
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detecting a slow to read cell in an SRAM array serviced by a local bit line pair; amplifying the voltage between said local bit line pair during a read operation in response to said detecting step. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A domino SRAM system comprising in combination:
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means to amplify a voltage difference across a local bit line pair; means to detect a slow to read cell in an SRAM array serviced by said local bit line pair; means to enable said means to amplify in response to detection of a slow to read cell. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification