Abstract: A content addressable memory (CAM) device includes a CAM array and a configuration circuit. The CAM array has a plurality of rows of CAM cells, each row segmented into a plurality of row segments, each row segment including a plurality of CAM cells coupled to a corresponding match line segment, and a match line control circuit having an input coupled to the corresponding match line segment, an output coupled to the match line segment in a next row segment, and a control terminal to receive a corresponding enable signal. The configuration circuit has an input to receive configuration information indicative of a width and depth configuration of the CAM array and having outputs to generate the enable signals.

Abstract: A CAM column structure includes an interface that drives search data to a plurality of CAM cells via a search line pair. The CAM cells are divided into sections, each section including: a set of CAM cells, a bit line pair coupled to the set of CAM cells, a sense amplifier coupled to the bit line pair, a tri-state read buffer configured to drive read data from the sense amplifier to the search line pair, and a pair of tri-state write buffers configured to drive write data from the search line pair to the bit line pair. In one embodiment, the pair of tri-state write buffers is replaced by a pair of switches that couple the search line pair to the sense amplifier. The search line pair may be segmented by tri-state buffers, which are controlled to drive the search, read and write data along the search line pair.

Abstract: A CAM device includes a CAM array coupled to a programmable priority encoding (PPE) logic circuit. The CAM array concurrently compares multiple input data with stored data to generate corresponding match results that are provided to the PPE logic circuit. The PPE logic circuit selectively favors the match results of a selected flow over the match results of the other flows in response to a flow select signal, which can be toggled to alternately select the match results of various flows. In this manner, the match results of the selected flow are generated and output even if the HPM index of the selected flow is of a lower priority than those of the non-selected flows, thereby ensuring an even distribution of match results reporting between different flows.

Abstract: The present invention discloses a butterfly match-line structure and a search method implemented thereby, wherein the parallelism of the match lines is increased to shorten the search time, and a butterfly-type connection is used to reduce the power consumption and achieve the best energy efficiency. Via the butterfly-type connection, information can be reciprocally transmitted between the parallel match lines, which are independent originally. When a miss case occurs, more succeeding memory cells will not be compared but will be turned off. Thereby, the power consumption is reduced. Further, XOR-based conditional keepers are used to reduce the matching time and the power consumption. Besides, such a circuit is also used to shorten the delay time of the butterfly-type connection.

Abstract: The present invention is directed to reduce array area and power consumption in a content addressable memory. A comparator for performing a match determination and a size determination is provided commonly for plural entries each storing data to be retrieved. Each entry includes data storage cells for storing data and mask cells for storing mask bits. The number of mask cells is smaller than that of the data storage cells. Search data is transmitted to the comparator via a search data bus. One of the entries is selected according to a predetermined rule. The comparator decodes the mask bits, generates a mask instruction signal, and performs match comparison and size comparison between the search data and data to be retrieved which is stored in the selected entry.

Abstract: Aspects of the disclosure provide a CAM module that can be used independent of a defective entry line. The CAM module can include at least a CAM array having at least X CAM entry lines, and an additional CAM entry line. Each CAM entry line may include a selection line for enabling the CAM entry line for writing and/or reading and an entry output for indicating matching to a search key. Further, the CAM module can include a decoder unit that can decode an address to enable one out of X word-lines, and an encoder unit that can encode X matching outputs to a matching address according to a predetermined priority sequence. Additionally, the CAM module can include a switching unit coupling the CAM array with the decoder unit and the encoder unit.

Abstract: The present invention provides a content addressable memory capable of higher frequency operation than conventional. When a search enable signal supplied from a search control circuit is asserted, each of search line drivers transfers search data to each CAM cell of a CAM memory array via a search line pair. The search line enable signal is transmitted to the search line drivers via a single control signal line coupled to the search control circuit. The control signal line is coupled to the search line drivers in such a manner that the search line enable signal passes through coupling nodes between the search line drivers and the control signal line in an arrangement order of the search line drivers from the side far away as viewed from match amplifiers.

Abstract: A read operation and a search operation are performed during the same cycle within a CAM system including a CAM array by: (1) forcing a non-matching condition to exist in the row of the CAM array selected for the read operation, (2) comparing the read data value with the search data value outside of the CAM array to determine whether a match exists, and (3) prioritizing the results of the search operation performed within the CAM array and the results of the comparison performed outside of the CAM array to provide a final search result.

Abstract: A content addressable memory (CAM) device includes a CAM array, a programmable interconnect structure, and a priority encoder. The CAM array includes a plurality of CAM rows, each row including a number of CAM cells for storing a data word and coupled to a match line that indicates a match result for the CAM row. The programmable interconnect structure is coupled to each CAM row and a plurality of CAM rows, each row including a number of CAM cells for storing a data word and coupled to a match line that indicates match results for the row. The programmable interconnect structure coupled to each CAM row, and is configured to logically connect any number N of selected CAM rows together to form a data word chain spanning N rows, regardless of whether the selected CAM rows are contiguous.

Abstract: An arbitration logic including one or more modular priority encoders. Each modular priority encoder includes a first logic circuit, a comparator circuit, a second logic circuit, and an encoder circuit. The first logic circuit may be configured to generate a first output signal in response to a plurality of request signals. The comparator circuit may be configured to compare all possible pairs of a plurality of priority signals. The second logic circuit may be configured to generate a control signal in response to (i) the plurality of request signals and (ii) a result of comparing all possible pairs of the plurality of priority signals. The encoder circuit may be configured to generate a second output signal in response to the control signal.

Abstract: Systems, devices, and methods, including executable instructions are provided for content addressable memory (CAM). One method includes defining the CAM into an array of data words having M rows and N columns, with each of N and M being greater than one. The data words of the CAM are arranged according to a 2-dimensional priority scheme. Data words outside a selected 1×M column are masked to be ignored in determining a match, and the CAM is searched. Each search includes N compare cycles and each compare cycle having a different 1×M column selected. A highest priority match per compare cycle is pipelined from a priority encoder with the pipelined matches arranged to communicate a priority order in a first dimension of the 2-dimensional priority scheme.

Abstract: A search engine device includes a lookup circuit, such as a content addressable memory (CAM) array. This lookup circuit is configured to generate multiple active match signals in response to detecting multiple matches between a search operand applied to said lookup circuit and multiple entries therein, during a search operation. A priority sequencer circuit is also provided. This priority sequencer circuit, which is electrically coupled to outputs of the lookup circuit, is configured to sequentially encode each of the multiple active match signals according to priority.

Abstract: A read operation and a search operation are performed during the same cycle within a CAM system including a CAM array by: (1) forcing a non-matching condition to exist in the row of the CAM array selected for the read operation, (2) comparing the read data value with the search data value outside of the CAM array to determine whether a match exists, and (3) prioritizing the results of the search operation performed within the CAM array and the results of the comparison performed outside of the CAM array to provide a final search result.

Abstract: For receiving an input data, a pattern data and a data clock signal and outputting a hit signal and an address signal, a content addressable memory is disclosed to include a plurality of content addressable memory units connected in series, each content addressable memory unit being adapted to receive the input data and the data clock signal and to output a comparison result signal, and an encoder coupled to the comparison result signal of each content addressable memory unit and adapted for outputting a hit signal and a memory address signal subject to the comparison result signal received.

Abstract: Systems, devices, and methods, including executable instructions are provided for resolving content addressable memory (CAM) match address priority. One method includes retaining a first match address as the best match address. Subsequent match addresses are compared to the retained best match address, each match address being associated with a compare cycle during which a selected columnar portion of each CAM entry is compared to a corresponding portion of a search term. The best match address is updated as a result of the comparison.

Abstract: A device includes a first semiconductor die. Nonvolatile memory stores information associated with a second semiconductor die. Cache memory caches a portion of the information. A cache controller controls the cache memory. A device interface communicates the information to the second semiconductor die. On the second semiconductor die, a semiconductor circuit processes the information stored on the first semiconductor die.

Abstract: Content addressable memory device utilizing phase change devices. An aspect of the content addressable memory device is the use of a comparatively lower power search-line access element and a comparatively higher power word-line access element. The word-line access element is only utilized during write operations and the search-line access element is only utilized during search operations. The word-line access element being electrically coupled to a second end of a phase change memory element and a word-line. The search-line access element also being electrically coupled to the second end of the phase change memory element and a search-line. The search-line being electrically coupled to a match-line. A bit-line is electrically coupled to a first end of the phase change memory element. Additionally, a complementary set of access elements, a complementary phase change memory element, a complementary search-line, and a complementary bit-line are also included in the content addressable memory device.

Abstract: A content-addressable memory (“CAM”) architecture and method for reducing power consumption thereof are described. A CAM cell array includes CAM cells, each of which includes two thyristor-based storage elements. Each thyristor-based storage element of the CAM cells has a control gate, an anode, and a cathode for providing control gates, anodes, and cathodes of the CAM cells. The CAM cell array further includes matchlines directly coupled to the cathodes of the CAM cells; searchlines directly coupled to the anodes of the CAM cell; and gatelines coupled to the control gates of the CAM cells.

Abstract: This patent describes a method for switching search-lines in a Content Addressable Memory (CAM) asynchronously to improve CAM speed and reduce CAM noise without affecting its power performance. This is accomplished by resetting the match-lines prior to initiating a search and then applying a search word to the search-lines. A reference match-line is provided to generate the timing for the search operation and provide the timing for the asynchronous application of the search data on the SLs. Additional noise reduction is achieved through the staggering of the search data application on the SLs through programmable delay elements.

Abstract: A plurality of content-addressable-memory sub-arrays simultaneously performs a parallel comparison between data sequences arranged in a row direction of memory cells and a search data sequence input from outside, and outputs a result of the comparison for each data sequence. A first input pin receives an input of the search data sequence. A second input pin receives an input of a search data sequence arbitrarily designating a content-addressable-memory sub-array. Each of the content-addressable-memory sub-arrays includes an activation control unit that controls activation of the content-addressable-memory sub-arrays based on the search data sequence.

Abstract: A search engine includes a storage module to store a plurality of data patterns, a plurality of busses to receive a plurality of representations of a search word, a selector corresponding to at least one of the plurality of data patterns to select one of the plurality of representations of the search word for comparing to the at least one of the plurality of data patterns, and a logic circuit operatively coupled to the storage module, to the plurality of busses, and to the selector to compare the selected one of the plurality of representations of the search word to the at least one of the plurality of data patterns.

Abstract: In a memory array structured of memory cells using a storage circuit STC and a comparator CP, either one electrode of a source electrode or a drain electrode of a transistor, whose gate electrode is connected to a search line, of a plurality of transistors structuring the comparator CP is connected to a match line HMLr precharged to a high voltage. Further, a match detector MDr is arranged on a match line LMLr precharged to a low voltage to discriminate a comparison signal voltage generated at the match line according to the comparison result of data. According to such memory array structure and operation, comparison operation can be performed at low power and at high speed while influence of search-line noise is avoided in a match line pair. Therefore, a low power content addressable memory which allows search operation at high speed can be realized.

Abstract: A priority encoder encodes an (N+1)-bit thermometer code, where N indicates a natural number. A plurality of selectors are arranged in a matrix of M rows and (N+1) columns, where M indicates a natural number, and select one of signals at first and second input terminals (1,0) in accordance with the value of a signal input to the control terminal. An output signal from the selector in the i-th row and (j?1)th column is input to the first input terminal of the selector in the i-th row and j-th column (1?i?M, 2?j?N+1), a predetermined value of 1 or 0 is input to the second input terminal of the selector in the i-th row and j-th column, and the j-th significant bit of the thermometer code is input to the control terminal of the selector in the i-th row and j-th column.

Abstract: The present invention is directed to reduce array area and power consumption in a content addressable memory. A comparator for performing a match determination and a size determination is provided commonly for plural entries each storing data to be retrieved. Each entry includes data storage cells for storing data and mask cells for storing mask bits. The number of mask cells is smaller than that of the data storage cells. Search data is transmitted to the comparator via a search data bus. One of the entries is selected according to a predetermined rule. The comparator decodes the mask bits, generates a mask instruction signal, and performs match comparison and size comparison between the search data and data to be retrieved which is stored in the selected entry.

Abstract: A content addressable memory (CAM) device (200) can provide for suppression of hit indications. Prioritized match indications (212) can be applied in parallel to both an encoding read-only-memory (ROM) (204-1) and suppression data store (206). A suppression data store (206) can output suppression bits (SH0 and SH1) that correspond to each CAM entry. Hit indications can be selectively suppressed according the values of suppression bits (SH0 and SH1). Hit suppression methods for a CAM device are also disclosed.

Abstract: A memory cell for use in a content-addressable memory comprises a first latch and a second latch. The first latch is operative to store a first bit associated with a first stored word, while the second latch is operative to store a second bit associated with a second stored word. The first and second latches collectively comprise a plurality of latch transistors. Each of the latch transistors comprises a respective channel. The channels of the latch transistors are oriented in substantially the same direction, resulting in a very compact memory cell implementation.

Abstract: A novel schematic for executing search, write and valid bit clear operations in one cycle in a CAM system that includes a plurality of CAM blocks is disclosed. In one embodiment, the plurality of CAM blocks are organized into at least one rectangular array having rows each having a plurality of CAM blocks, a group of CAM cells and associated read/write bit lines connecting the group of CAM cells to an addressed search circuit. The write operation depends on the output of the search operation, wherein the same data is written in to the CAM when the search operation results in a miss in a given cycle. Further, during the same cycle a valid bit clear operation is also performed. The resulting CAM cell provides a high speed three port operation.

Abstract: A content addressable memory (CAM) device having CAM cells arranged in rows and columns. A plurality of pairs of data lines extend along respective columns of the CAM cells, each pair of data lines including at least one data line that is formed by conductive segments disposed in two different conductivity layers of the CAM device.

Abstract: A low power content addressable memory system comprising an array of content addressable memory cells organized as a plurality of equal sized CAM cell groups, each CAM cell group having one or more CAM cells; a valid entry tag bit associated with each said content addressable memory cell; a match output generator connected to the output of each CAM cell and an enabling means having its first input connected to the valid entry tag bit, its second input connected to a match control signal and its output connected to the corresponding match output generator such that said match output generator is enabled only if said valid entry tag bit indicates a valid entry.

Abstract: A content addressable memory (CAM) device having a multi-row write function. The CAM device includes a CAM array and an address circuit. The CAM array includes a plurality of CAM cells and word lines coupled to respective rows of the CAM cells. The address circuit is coupled to the CAM array and configured to activate a plurality of the word lines simultaneously to enable a write value to be stored within a selected plurality of the rows of CAM cells.

Abstract: A plurality of content-addressable-memory sub-arrays simultaneously performs a parallel comparison between data sequences arranged in a row direction of memory cells and a search data sequence input from outside, and outputs a result of the comparison for each data sequence. A first input pin receives an input of the search data sequence. A second input pin receives an input of a search data sequence arbitrarily designating a content-addressable-memory sub-array. Each of the content-addressable-memory sub-arrays includes an activation control unit that controls activation of the content-addressable-memory sub-arrays based on the search data sequence.

Abstract: A CAM cell array according to embodiments of the present invention include an array of CAM cells, each of the CAM cells comprising a first cell, the first cell including a non-volatile storage element coupled to at least one first data line and a match line; a match line controller coupled to the match line; and a data line controller coupled to the data lines, wherein a write operation is performed by changing a state of the non-volatile storage element by providing data to the at least one data line, wherein a read operation is performed by determining the state of the non-volatile storage element through the at least one data line, and wherein a comparison operation is performed by applying data to the at least one data line and determining a match condition on the match line.

Abstract: A device is fabricated on a flash process semiconductor die. The device includes main memory to store processor information. A cache memory caches a portion of the processor information. A cache controller controls the cache memory. A device interface communicates the processor information to another semiconductor die. Control logic controls the device interface.

Abstract: A content addressable memory (CAM) device can include a plurality of CAM super-blocks each comprising a plurality of sub-blocks. Each sub-block can include a plurality of CAM entries that generate match results in response to a key value. For each sub-block there can be storage for a programmable local priority value that establishes priority of match results of the sub-block with respect to match results of the other sub-blocks of the same CAM super-block. In addition, for each sub-block there can be a programmable global priority value, different from the programmable local priority value, that establishes priority of match indications of the sub-block with respect to match results of sub-blocks of the plurality of CAM super-blocks.

Abstract: A novel match/mismatch emulation scheme for an addressed location in a CAM system that includes a plurality of CAM blocks. The plurality of CAM blocks are organized into at least one rectangular array having rows each having a plurality of CAM blocks, a group of CAM cells and associated read/write bit lines connecting the group of CAM cells to an addressed search circuit. During debug mode, where the individual array cells do not participate in search, all the cells in the debug column behave the same way to emulate a match/mismatch on all words. The circuit provides a control input to include address evaluation of a debug cell in a row. The circuit also provides simultaneous switching noise analysis on an evaluating row. The resulting CAM cell provides a circuit to test individual rows for defects and noise analysis.

Abstract: A CAM (Content Addressable Memory) cell includes first and second data storage portions storing data, horizontal port write gates for storing data applied through a match line pair in the data storage portions in a data write through a horizontal port, and search/read gates for driving the match lines of the match line pair in accordance with the data stored in the data storage portions in a search operation and in a data read through the horizontal port. The match lines are used as horizontal bit line pair, or signal lines for accessing the horizontal port. As the first and second data storage portions are used, it becomes possible to store ternary data, and accordingly, a write mask function of inhibiting a data write at a destination of data transfer is realized. Further, as the CAM cell is used, an arithmetic/logic operation following a search process can be executed selectively, and high speed data writing/reading becomes possible.

Abstract: Systems, devices, and methods, including executable instructions are provided for content addressable memory (CAM). One method includes defining the CAM into an array of data words having M rows and N columns, with each of N and M being greater than one. The data words of the CAM are arranged according to a 2-dimensional priority scheme. Data words outside a selected 1×M column are masked to be ignored in determining a match, and the CAM is searched. Each search includes N compare cycles and each compare cycle having a different 1×M column selected. A highest priority match per compare cycle is pipelined from a priority encoder with the pipelined matches arranged to communicate a priority order in a first dimension of the 2-dimensional priority scheme.

Abstract: Systems, devices, and methods, including executable instructions are provided for resolving content addressable memory (CAM) match address priority. One method includes retaining a first match address as the best match address. Subsequent match addresses are compared to the retained best match address, each match address being associated with a compare cycle during which a selected columnar portion of each CAM entry is compared to a corresponding portion of a search term. The best match address is updated as a result of the comparison.

Abstract: A system for identifying asserted signals includes a plurality of input ports, a priority encoding module, and a match module. The plurality of input ports receive one of a plurality of input signals. The priority encoding module is coupled to the plurality of input ports and outputs a signal indicating a highest-priority input signal that is asserted. The match module is also coupled to the plurality of input ports and receives a plurality of match detect signals from the priority encoding module. Each match detect signal is associated with a particular input signal and indicates whether another input signal having a higher-priority than the associated input signal is asserted. The match module also generates a multiple match signal based on the input signals and the match detect signals. The multiple match signal indicates whether more than one of the input signals is asserted.

Abstract: 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.