Abstract: An analog error correction circuit is disclosed that implements an analog error correction code. The analog circuit includes a crossbar array of memristors or other non-volatile tunable resistive memory devices. The crossbar array includes a first crossbar array portion programmed with values of a target computation matrix and a second crossbar array portion programmed with values of an encoder matrix for correcting computation errors in the matrix multiplication of an input vector with the computation matrix. The first and second crossbar array portions share the same row lines and are connected to a third crossbar array portion that is programmed with values of a decoder matrix, thereby enabling single-cycle error detection. A computation error is detected based on output of the decoder matrix circuitry and a location of the error is determined via an inverse matrix multiplication operation whereby the decoder matrix output is fed back to the decoder matrix.

Abstract: Embodiments of the disclosure provide a system, method, or computer readable medium for programming a target analog voltage range of an analog content addressable memory (aCAM) row. The method may comprise calculating a threshold current sufficient to switch a sense amplifier (SA) on and discharge a match line (ML) connected to a cell of the aCAM; and based on calculating the threshold current, programming a match threshold value by setting a memristor conductance in association with the target analog voltage range applied to a data line (DL) input. The target analog voltage range may comprise a target analog voltage range vector.

Abstract: Systems and methods for an optical ternary content addressable memory (TCAM) are provided. The optical TCAM implements a time-division multiplexing (TDM) based encoding scheme to encode each bit position of a search word in the time domain. Each bit position is associated with at least two time slots. The encoded optical signal comprising the search word is routed through one or more modulators configured to represent a respective TCAM stored word. If a mismatch between at least one bit position of the search word and at least one TCAM stored word occurs, a photodetector or photodetector array will detect light.

Abstract: Systems are methods are provided for implementing an analog content addressable memory (analog CAM), which is particularly structured to allow for an amount of variance (fuzziness) in its search operations. The analog CAM may search for approximate matches with the data stored therein, or matches within a defined variance. Circuitry of the analog CAM may include transistor-source lines that receive search-variance parameters, and/or data lines that receive search-variance parameters explicitly within the search input data. The search-variance parameters may include an upper bound and a lower bound that define a range of values within the allotted amount of fuzziness (e.g., deviation from the stored value). The search-variance parameters may program (using analog approaches) the analog CAM to perform searches having a modifiable restrictiveness that is tuned dynamically, as defined by the input search-variance. Thus, highly efficient hardware for complex applications involving fuzziness are enabled.

Abstract: Systems and methods provide new circuits that increase aCAM precision by leveraging the concept of range segmenting to representationally store an analog voltage range across multiple aCAM cells/sub-circuits (here the representationally stored analog voltage range may correspond to a word entry). In this way, a circuit of the presently disclosed technology can increase precision (e.g., the number of programmable levels that can be used to store a word entry and/or the number of programmable levels that an input signal can be search against) linearly with each aCAM cell/sub-circuit added to the circuit. Accordingly, circuits of the presently disclosed technology can be used to carry out more complex computations than conventional aCAMs—and thus can be used in a wider range of computational applications.

Abstract: An analog content addressable memory (aCAM) that enables parallel searching of analog ranges of values and generates analog outputs that quantify matches between input data and stored data is disclosed. The input data can be compared with the stored data, and the input data can be determined to match the stored data based on a value associated with the input data being within a range associated with the stored data. The aCAM can generate an analog output that represents a number of matches and a number of mismatches between the input data and the stored data. Based on the analog output, whether the input data matches the stored data and a degree to which the input data matches the stored data can be determined.

Abstract: An analog error correction circuit is disclosed that implements an analog error correction code. The analog circuit includes a crossbar array of memristors or other nonvolatile tunable resistive memory devices. The crossbar array includes a first crossbar array portion programmed with values of a target computation matrix and a second crossbar array portion programmed with values of an encoder matrix for correcting computation errors in the matrix multiplication of an input vector with the computation matrix. The first and second crossbar array portions share the same row lines and are connected to a third crossbar array portion that is programmed with values of a decoder matrix, thereby enabling single-cycle error detection. A computation error is detected based on output of the decoder matrix circuitry and a location of the error is determined via an inverse matrix multiplication operation whereby the decoder matrix output is fed back to the decoder matrix.

Abstract: Systems are methods are provided for implementing an analog content addressable memory (analog CAM), which is particularly structured to allow for an amount of variance (fuzziness) in its search operations. The analog CAM may search for approximate matches with the data stored therein, or matches within a defined variance. Circuitry of the analog CAM may include transistor-source lines that receive search-variance parameters, and/or data lines that receive search-variance parameters explicitly within the search input data. The search-variance parameters may include an upper bound and a lower bound that define a range of values within the allotted amount of fuzziness (e.g., deviation from the stored value). The search-variance parameters may program (using analog approaches) the analog CAM to perform searches having a modifiable restrictiveness that is tuned dynamically, as defined by the input search-variance. Thus, highly efficient hardware for complex applications involving fuzziness are enabled.

Abstract: Systems and methods are provided for employing analog content addressable memory (aCAMs) to achieve low latency complex distribution sampling. For example, an aCAM core circuit can include an aCAM array. Amplitudes of a probability distribution function are mapped to a width of one or more aCAM cells in each row of the aCAM array. The aCAM core circuit can also include a resistive random access memory (RRAM) storing lookup information, such as information used for processing a model. By randomly selecting columns to search of the aCAM array, the mapped probability distribution function is sampled in a manner that has low latency. The aCAM core circuit can accelerate the sampling step in methods relying on sampling from arbitrary probability distributions, such as particle filter techniques. A hardware architecture for an aCAM Particle Filter that utilizes the aCAM core circuit as a central structure is also described.

Abstract: Embodiments of the disclosure provide a system, method, or computer readable medium for programming a target analog voltage range of an analog content addressable memory (aCAM) row. The method may comprise calculating a threshold current sufficient to switch a sense amplifier (SA) on and discharge a match line (ML) connected to a cell of the aCAM; and based on calculating the threshold current, programming a match threshold value by setting a memristor conductance in association with the target analog voltage range applied to a data line (DL) input. The target analog voltage range may comprise a target analog voltage range vector.

Abstract: Examples described herein relate to a decision tree computation system in which a hardware accelerator for a decision tree is implemented in the form of an analog Content Addressable Memory (a-CAM) array. The hardware accelerator accesses a decision tree. The decision tree comprises of multiple paths and each path of the multiple paths includes a set of nodes. Each node of the decision tree is associated with a feature variable of multiple feature variables of the decision tree. The hardware accelerator combines multiple nodes among the set of nodes with a same feature variable into a combined single node. Wildcard values are replaced for feature variables not being evaluated in each path. Each combined single node associated with each feature variable is mapped to a corresponding column in the a-CAM array and the multiple paths of the decision tree to rows of the a-CAM array.

Abstract: Encoding of domain logic rules in an analog content addressable memory (aCAM) is disclosed. By encoding domain logic in an aCAM, rapid and flexible search capabilities are enabled, including the capability to search ranges of analog values, fuzzy match capabilities, and optimized parameter search capabilities. This is achieved with low latency by using only a small number of clock cycles at low power. A domain logic ruleset may be represented using various data structures such as decision trees, directed graphs, or the like. These representations can be converted to a table of values, where each table column can be directly mapped to a corresponding row of the aCAM.

Abstract: Systems, devices, circuits, methods, and non-transitory computer readable media that enable storing and searching arbitrary segments of ranges of analog values are disclosed. Various analog content addressable memory (aCAM) circuit implementations having the capability to store and search outside of a range of values, within any of multiple disjoint ranges, or outside of multiple ranges are disclosed. The disclosed aCAM circuit implementations make searching for complex input features more flexible and efficient, thereby yielding a technological improvement over conventional solutions. In some implementations, an aCAM may include multiple pull-down transistors connected in series to a match line that is pre-charged, in which case, the aCAM detects a match if the match line is not discharged by the pull-down transistors, which occurs if at least one pull-down transistor is in an OFF state. In other implementations, an aCAM includes pass gates connected to a match line to detect a match.

Abstract: A DPE memristor crossbar array system includes a plurality of partitioned memristor crossbar arrays. Each of the plurality of partitioned memristor crossbar arrays includes a primary memristor crossbar array and a redundant memristor crossbar array. The redundant memristor crossbar array includes values that are mathematically related to values within the primary memristor crossbar array. In addition, the plurality of partitioned memristor crossbar arrays includes a block of shared analog circuits coupled to the plurality of partitioned memristor crossbar arrays. The block of shared analog circuits is to determine a dot product value of voltage values generated by at least one partitioned memristor crossbar array of the plurality of partitioned memristor crossbar arrays.

Abstract: Systems, devices, circuits, methods, and non-transitory computer readable media that enable storing and searching arbitrary segments of ranges of analog values are disclosed. Various analog content addressable memory (aCAM) circuit implementations having the capability to store and search outside of a range of values, within any of multiple disjoint ranges, or outside of multiple ranges are disclosed. The disclosed aCAM circuit implementations make searching for complex input features more flexible and efficient, thereby yielding a technological improvement over conventional solutions. In some implementations, an aCAM may include multiple pull-down transistors connected in series to a match line that is pre-charged, in which case, the aCAM detects a match if the match line is not discharged by the pull-down transistors, which occurs if at least one pull-down transistor is in an OFF state. In other implementations, an aCAM includes pass gates connected to a match line to detect a match.

Abstract: An analog content addressable memory (aCAM) that enables parallel searching of analog ranges of values and generates analog outputs that quantify matches between input data and stored data is disclosed. The input data can be compared with the stored data, and the input data can be determined to match the stored data based on a value associated with the input data being within a range associated with the stored data. The aCAM can generate an analog output that represents a number of matches and a number of mismatches between the input data and the stored data. Based on the analog output, whether the input data matches the stored data and a degree to which the input data matches the stored data can be determined.

Abstract: Examples disclosed herein relate to digital hash code generation. A digital hash code generating device comprising a plurality of variable conductance elements. Each variable conductance element is coupled to a selected row line and to a selected column line of a crossbar array. Each variable conductance element comprises a conductance from a stochastic distribution of conductance. A plurality of comparator elements and each comparator element is connected to a set of at least two column lines. The plurality of comparator elements generates a hash code in response to a vector input applied to the plurality of row lines of the crossbar array.

Abstract: Disclosed techniques provide for dynamically changing precision of a multi-stage compute process. For example, changing neural network (NN) parameters on a per-layer basis depending on properties of incoming data streams and per-layer performance of an NN among other considerations. NNs include multiple layers that may each be calculated with a different degree of accuracy and therefore, compute resource overhead (e.g., memory, processor resources, etc.). NNs are usually trained with 32-bit or 16-bit floating-point numbers. Once trained, an NN may be deployed in production. One approach to reduce compute overhead is to reduce parameter precision of NNs to 16 or 8 for deployment. The conversion to an acceptable lower precision is usually determined manually before deployment and precision levels are fixed while deployed.

Abstract: Encoding of domain logic rules in an analog content addressable memory (aCAM) is disclosed. By encoding domain logic in an aCAM, rapid and flexible search capabilities are enabled, including the capability to search ranges of analog values, fuzzy match capabilities, and optimized parameter search capabilities. This is achieved with low latency by using only a small number of clock cycles at low power. A domain logic ruleset may be represented using various data structures such as decision trees, directed graphs, or the like. These representations can be converted to a table of values, where each table column can be directly mapped to a corresponding row of the aCAM.

Abstract: Examples described herein relate to a decision tree computation system in which a hardware accelerator for a decision tree is implemented in the form of an analog Content Addressable Memory (a-CAM) array. The hardware accelerator accesses a decision tree. The decision tree comprises of multiple paths and each path of the multiple paths includes a set of nodes. Each node of the decision tree is associated with a feature variable of multiple feature variables of the decision tree. The hardware accelerator combines multiple nodes among the set of nodes with a same feature variable into a combined single node. Wildcard values are replaced for feature variables not being evaluated in each path. Each combined single node associated with each feature variable is mapped to a corresponding column in the a-CAM array and the multiple paths of the decision tree to rows of the a-CAM array.