Integrated Device Technology, Inc.

Netlogic Microsystems, Inc

Chau-Chin Wu

Chuen-Der Lien

Ta-Ke Tien

Richard C Li

Kee W Park

Mark W Baumann

James Lin

Tzong-Kwang Henry Yeh

Michael J Miller

John R Mick

Scott Yu-Fan Chu

Wen-Kuan Fang

Kuo-Huei Yen

Chuen Der Lien

A method and apparatus for a CAM with reduced cross-coupling interference have been disclosed.

Method and apparatus for CAM with reduced cross-coupling interference

A CAM array including volatile or non-volatile ternary CAM cells that discharge their associated match line through a special discharge line (e.g., a low match line), instead of through the bit line, is disclosed. Each ternary CAM cell includes a pair of storage elements that are used to store a data bit value, a comparison element that is used to compare the stored value with an applied data value, and a discharge element that is coupled between the discharge line and the match line. During operation, when the applied data value matches the stored value, the discharge element de-couples the discharge line from the match line (i.e., a high voltage on the match line remains high). Conversely, when the applied data value does not match the stored value, the discharge elements couple the discharge line to the match line, thereby discharging the match line to the discharge line. By discharging the match line to the discharge line instead of the bit lines of the CAM array, the size of the CAM array is not limited by the length bit lines. Because the voltage on the match line is sensed to determine the match/no-match condition of a CAM cell, the match line does not need to be completely discharged.

CAM arrays having CAM cells therein with match line and low match line connections and methods of operating same

A charge recycling integrated circuit and a method for integrated circuit charge recycling. In one aspect, a charge storage collector is interposed between a high voltage supply or a low voltage supply and a function block of the integrated circuit. The charge collector is operable to selectively store a charge dissipated in the function block when the logic circuitry of the function block switches between a high voltage value and a low voltage value. The dissipated charge resulting from the switching in the logic circuitry of the function block is selectively stored to the charge collector and the charge collector selectively returns the charge stored on the charge collector to the high voltage supply, the low voltage supply or to another node in the integrated circuit as appropriate.

System and method for integrated circuit charge recycling

A dual-port Static Random Access Memory (SRAM) cell is disclosed that includes a storage element that is operable to store a data bit and a complement data bit. The dual-port SRAM cell further includes read access circuitry dedicated exclusively to a read operation and write access circuitry dedicated exclusively to a write operation. The read operation and the write operation are performed in a staggered manner. With the read operation performed exclusive on one port and the write operation performed exclusively on the other port of the SRAM cell, smaller transistors can be used to reduce the size of the SRAM cell.

Reduced size dual-port SRAM cell

Search engine devices include a content addressable memory (CAM) core having a plurality of CAM array blocks therein and a control circuit. The control circuit, which is electrically coupled to the plurality of CAM array blocks, is configured to perform built-in self repair (BISR) of hard memory defects and/or compare logic defects in the plurality of CAM array blocks concurrently with operations to search entries in the plurality of CAM array blocks.

Content addressable memory (CAM) devices that support background BIST and BISR operations and methods of operating same

A content addressable memory (CAM) cell that includes a static random access memory (SRAM) cell that operates in response to a Vsupply voltage. A first set of bit lines coupled to the SRAM cell are used to transfer data values to and from the SRAM cell. The signals transmitted on the first set of bit lines have a signal swing equal to the Vsupply voltage. A second set of bit lines is coupled to receive a comparison data value. The signals transmitted on the second set of bit lines have a signal swing that is less than the Vsupply voltage. For example, the signal swing on the second set of bit lines can be as low as two transistor threshold voltages. The second set of bit lines is biased with a supply voltage that is less than the Vsupply voltage. A sensor circuit is provided for comparing the data value stored in the CAM cell with the comparison data value. The sensor circuit pre-charges a match scan line prior to a compare operation. If the data value stored in the CAM cell does not match the comparison data value, the match sense line is pulled down. The signal swing of the match sense line is smaller than the Vsupply voltage. For example, the signal swing on the match sense line can be as low as one transistor threshold voltage.

Content addressable memory (CAM) arrays and cells having low power requirements

Content addressable memory (CAM) devices according to embodiments of the present invention include high performance multiple match detection circuits therein. These match detection circuits use 2-to-1 multiple match gates that are small, consume no static power and are hierarchically cascadable. The match detection circuits are also configured so that match signal inputs see small fanouts and high speed operation can be achieved. At each intermediate and final stage of the match detection circuit, the multiple match gates process two pairs of inputs into a single pair of outputs. In particular, a match detection circuit is configured to generate a final multiple match flag (MMF) and a final any match flag (AMF) in response to input match signals, with the match detection circuit including logN stages of 2-to-1 multiple match gates, where N=2and k is a positive integer. The final MMF is set to an active level whenever at least two of the input match signals indicate a match condition and the AMF is set to an active level whenever at least one of the input match signals indicates a match condition.

Content addressable memory (CAM) devices having scalable multiple match detection circuits therein

Content addressable memory (CAM) devices include error detection and correction (EDC) control circuits therein. The EDC control circuit operates to correct soft errors in entries within a plurality of internal CAM array blocks with, at most, limited interruption to other operations performed by the CAM device. The EDC control circuit utilizes a multi-bit check word associated with each entry to detect a soft error and perform one-bit error correction on the entry. The EDC control circuit is configured to be active during a background mode of operation when the CAM array blocks are undergoing search operations in a foreground mode of operation. A CAM array block may also include a column of dual-function check bit cells that are configured to operate as a column of CAM cells when necessary to replace a defective column of CAM cells.

Content addressable memory (CAM) devices having error detection and correction control circuits therein and methods of operating same

Multiple match detection logic and gates for content addressable memory (CAM) devices

A CAM device includes an array of multi-compare port CAM cells therein. The CAM cells are configured to support concurrent search operations between multiple distinct search words and entries within the rows of the CAM array. These concurrent search operations may be performed in-sync with respective clock signals that are asynchronous relative to each other.

Content addressable memory (CAM) devices that utilize multi-port CAM cells and control logic to support multiple overlapping search cycles that are asynchronously timed relative to each other

An integrated circuit having an electrostatic discharge (ESD) protection circuit, a core protection circuit, a sensitive core circuit and peripheral circuitry is provided. The ESD protection circuit is coupled between the V voltage supply terminal and the V voltage supply terminal, and is capable of providing protection to the peripheral circuitry. The ESD protection circuitry requires help from core protection circuit to protect the sensitive core circuit. The core protection circuit and the sensitive core circuit are coupled in series between the V and V voltage supply terminals, with the core protection circuit coupled to the V voltage supply terminal. The sensitive core circuit has a V voltage supply terminal coupled to receive a V supply voltage from the core protection circuit. The core protection circuit is configured to cause the V supply voltage to rise slowly with respect to a rising voltage on the V voltage supply terminal during power-on of the integrated circuit. The core protection circuit is further configured to disconnect the V voltage supply terminal from the V voltage supply when a voltage on the V voltage supply terminal exceeds the nominal V supply voltage by a predetermined amount.

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Cupertino, CA, United States of America

Chau-Chin Wu