International Business Machines Corporation

Jagreet S Atwal

Kerry Bernstein

Robert J Bucki

Joseph S Barnes

Eric Francis Robinson

Jason Alan Cox

Thoai Thai Le

An improved multi-port register file system and method of operating. The multi-port register file memory system comprises: n single memory bit cells each storing a data value and having a single bit cell write port and a single read port connecting a respective local bit line, wherein corresponding parallel activated single bit cells output a stored data value in parallel at n read port outputs to a respective local bit line of n local bit lines, each single bit cell accessed in parallel according to a decoded read address signal. A receiver device is provided implementing n selection logic devices corresponding to n read ports, each selection logic device receiving each the n local bit line output values from the n single bit cells, and implementing logic based directly on the decoded read address signal to select a respective local bit line output as a global output bit.

Multiple read port memory system with a single port memory cell

A multi-wafer CAM cell in which the negative effects of increased travel distance have been substantially reduced is provided. The multi-wafer CAM cell is achieved in the present invention by utilizing three-dimensional integration in which multiple active circuit layers are vertically stack and vertically aligned interconnects are employed to connect a device from one of the stacked layers to another device in another stack layer. By vertically stacking multiple active circuit layers with vertically aligned interconnects, each compare port of the inventive CAM cell can be implemented on a separate layer above or below the primary data storage cell. This allows the multi-wafer CAM structure to be implemented within the same area footprint as a standard Random Access Memory (RAM) cell, minimizing data access and match compare delays.

Multi-wafer 3D CAM cell

A multi-ported CAM cell in which the negative effects of increased travel distance have been substantially reduced is provided. The multi-ported CAM cell is achieved in the present invention by utilizing three-dimensional integration in which multiple active circuit layers are vertically stack and vertically aligned interconnects are employed to connect a device from one of the stacked layers to another device in another stack layer. By vertically stacking multiple active circuit layers with vertically aligned interconnects, each compare port of the multi-port CAM can be implemented on a separate layer above or below the primary data storage cell. This allows the multi-port CAM structure to be implemented within the same area footprint as a standard Random Access Memory (RAM) cell, minimizing data access and match compare delays. Each compare match line and data bit line has the length associated with a simple two-dimensional Static Random Access Memory (SRAM) cell array.

Compact multi-port CAM cell implemented in 3D vertical integration

Compact multi-port cam cell implemented in 3D vertical integration

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Carrboro, NC, United States of America

Jagreet S Atwal