Multi-bit PROM memory cell
AssigneeHewlett-Packard Development Company, L.P.
InventorsCraig M. Perlov, Ping Mei
Life of this patent
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Abstract
A memory cell comprises at least two antifuses in series with a diode. Each antifuse expresses a different resistance from the others when blown, and each requires an escalating programming voltage over the last to be programmed. The antifuse structures differ in their respective geometries and materials so that a low programming voltage will blow the more sensitive fuse first, and a higher voltages will program the lesser sensitive fuses thereafter.
Claims14
A multi-bit memory cell, comprising:
- a first antifuse providing for programming to a lower first resistance when a programming voltage exceeding a first programming voltage level is exceeded;
- and
- a second antifuse in electrical series with the first antifuse and providing for programming to a lower second resistance when said programming voltage exceeds a second programming voltage level.
A method for storing multi-bit binary values in a single memory cell, the method comprising the steps of:
- arranging dissimilar antifuse devices in electrical series with one another, wherein the dissimilarity is such that differing programming voltage levels are required to uniquely program particular ones of said antifuse devices;
- programming particular ones of said antifuse devices by applying a programming voltage level that represents an encoding of a multi-bit binary value;
- and
- reading back said multi-bit binary value by sensing how many of said dissimilar antifuse devices have reacted to said programming voltage level.
A multi-bit memory cell, comprising:
- a first fuse providing for programming to a higher first resistance when a programming current exceeding a first programming current level is exceeded;
- and
- a second fuse in electrical series with the first fuse and providing for programming to a different higher second resistance when said programming current exceeds a second programming current level.
A method for storing multi-bit binary values in a single memory cell, the method comprising the steps of:
- arranging dissimilar fuse devices in electrical series with one another, wherein the dissimilarity is such that differing programming current levels are required to uniquely program particular ones of said fuse devices;
- programming particular ones of said fuse devices by applying a programming current level that represents an encoding of a multi-bit binary value;
- and
- reading back said multi-bit binary value by sensing how many of said dissimilar fuse devices have reacted to said programming current level.
Dependencies are inferred from the claim text.