Texas Instruments Corporation

Santhosh Narayanaswamy

Rashmi Sachan

Bryan David Sheffield

Sharad Kumar Gupta

Robert J Landers

George B Jamison

Lakshmikantha V Holla

Nisha Padattil Kuliyampattil

Memory circuit and a tracking circuit thereof. The tracking circuit includes a dummy bit line (DBL). The tracking circuit further includes a first circuit to discharge the dummy bit line in response to a first signal and a wordline activation signal. The wordline activation signal causes activation of a memory cell. The tracking circuit also includes a second circuit which is responsive to discharge of the dummy bit line to enable access to the memory cell.

Memory circuit and a tracking circuit thereof

A technique that provides width expansion of two CAMs of varying widths by combining match results from two CAMs by integrating the two CAMs. In one embodiment, a synchronizer circuit triggers the operation of an External Priority Encoder module which can be used to cascade two CAMs to form a wider CAM. When the External Priority Encoder module is used with the CAM, the External Priority Encoder module will receive MATCH signals and control signals from individual CAMs residing on either side, and will be triggered by the last arriving signal between two ports associated with two CAMs. In case one of the ports is disabled the External Priority Encoder module relies totally on the control signal from the other port for operation. The synchronizer circuit has the ability to handle mismatches between the CAMs as well as differentiating valid and invalid combinations between the CAMs.

Technique for CAM width expansion using an external priority encoder

A technique that provides highly scalable width expansion architecture for cascading CAMs to facilitate searching of increased wordlengths. In one example embodiment, this is achieved by combining a plurality of CAM devices in a serial cascade arrangement. Each CAM device of the serial cascade arrangement receives a portion of the search word. Each of the CAM devices in the serial cascade arrangement includes a CAM, a plurality of GMAT lines, a dummy match line, and a GMAT interface circuitry. The GMAT interface circuitry facilitates driving the match signals from a substantially previous CAM to a substantially adjacent CAM. The last CAM device is coupled to a match latch and a priority encoder. The first CAM device provides a single mismatch signal on an associated dummy match line for coordinating match signals associated with the plurality of GMAT lines of each of the plurality of CAM devices and to transfer the match signals from the last CAM device to the match latch circuit and the priority encoder and to output a combined search result.

High performance and scalable width expansion architecture for fully parallel CAMs

An area efficient stacked TCAM cell for fully parallel search. The TCAM cell includes a top half circuit portion interconnected with a replicated bottom half circuit portion such that there is a shared match line between each of the half circuit portions. Each TCAM cell includes a pair of memory elements that is connected to a pair of associated compare circuits such that the interconnections between the memory elements and the compare circuits are substantially vertical in active MOS layers and substantially horizontal in metal layers. The memory elements and the compare circuits are connected such that they facilitate shorter interconnections and sharing of terminals at the boundary of adjacent cells. The resulting stacked TCAM cell provides shorter match lines, shared bit lines, and reduced silicon area to facilitate improved routing and performance.

Area efficient stacked TCAM cell for fully parallel search

A technique to enhance performance and reduce silicon area for a TCAM system which includes a plurality of CAM blocks that are organized into at least one rectangular array having rows each having a plurality of CAM blocks, a group of TCAM cells and associated read/write bit lines connecting the group of CAM cells to search bit lines. Each TCAM cell in the TCAM architecture includes a pair of memory elements that is connected to a pair of associated compare circuits such that the interconnections between the memory elements and the compare circuits are substantially vertical in active MOS layers and substantially horizontal in the metal layers to facilitate sharing of adjacent cells thereby providing reduced silicon area and a short aspect ratio.

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Bengaluru, India

Santhosh Narayanaswamy