International Business Machines Corporation

Robert J Bucki

Kerry Bernstein

Jagreet S Atwal

Joseph S Barnes

Sang Hoo Dhong

Joel Abraham Silberman

Osamu Takahashi

Eric Francis Robinson

Jeffrey Herbert Fischer

Jason Alan Cox

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

A method of designing a logic circuit includes providing a leaf cell having at least one transistor. The leaf is suitable for use as a 1-cell or a 0-cell in the logic circuit. A first array of abutting leaf cells is tiled using at least one 1-cell and at least one 0-cell to define at least one logical expression by the relative positions of the array cells. Length optimized interconnects are added to the array. Each length optimized interconnect terminates at a last leaf cell in the array to which the interconnect makes contact. The leaf cell may be a floating leaf cell in which any pair of abutting cells are electrically isolated from one another until the length optimized interconnects are added to the design. The leaf cell array likely includes a set of rows and a set of columns in which the leaf cells in each row and the set of columns each correspond to an input of the logical expression.

Wire trimmed programmable logic array

A dynamic node keeper device for a dynamic strobe circuit is controlled by the signal at the intermediate node, that is, the signal at the output of the strobe component. By controlling the dynamic node keeper device through the strobe component output, the keeper device is active or conductive only when necessary to protect against noises in the pull down network for the strobe circuit. At all other times in the course of operation of the dynamic strobe circuit, the dynamic node keeper device according to the invention is nonconductive or inactive. Thus, the dynamic strobe circuit according to the invention reduces power consumption.

Strobe circuit keeper arrangement providing reduced power consumption

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Cary, NC, United States of America

Robert J Bucki