A reconfigurable content addressable memory system and method

Abstract

This invention discloses a reconfigurable content-addressable memory system and method. The system includes: an input voltage driving module for converting search data input from the main processor into an analog voltage signal and using it as the voltage input to the content-addressable memory array for searching; a content-addressable memory array for storing data, comparing the search data input in analog voltage form with the stored data, and outputting the matching degree in analog voltage or current form; a configurable current / voltage sensing module for converting the input analog voltage or current into a digital signal and returning the result to the main processor; and a main processor for analyzing the digital signal to obtain the matching result of each stored data item with the search data. This invention enables two configurable search functions to be implemented in the same array and circuit, effectively reducing additional array and circuit overhead.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics technology, and more specifically, relates to a reconfigurable content addressable memory system and method. Background Technology

[0002] Content-addressable memory (COM) is a highly efficient type of memory for data retrieval. It can achieve highly parallel data searching and output the matching results of all stored data and search data in a single search operation.

[0003] Large-scale information retrieval systems, due to their massive data volumes, require a fuzzy, rapid initial screening to remove data with low similarity before performing precise data searches. However, traditional content-addressable memories (COMs) based on static random access memory (SRAM) can only achieve precise searches, and COMs based on linear memristors can only implement one of these two search functions. Therefore, additional arrays and circuits are needed to achieve both search functions, which significantly reduces system area efficiency and energy efficiency. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a reconfigurable content addressable memory system and method that can implement two configurable search functions in the same array and circuit, effectively reducing additional array and circuit overhead.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a reconfigurable content addressable memory system, including an input voltage driving module, a content addressable memory array, a configurable current / voltage sensing module and a main processor. The configurable current / voltage sensing module is used to switch between current or voltage sensing modes according to search requirements. The current and voltage sensing modes correspond to fuzzy filtering and precise search functions, respectively.

[0006] The input voltage driving module is used to convert the search data input by the main processor into an analog voltage signal and output it to the content addressable memory array.

[0007] The content-addressable memory array is used to store data and compare the stored data with search data input in the form of analog voltage in parallel. Then, according to the sensing mode, it outputs the matching degree represented by analog current or voltage to the configurable current / voltage sensing module in parallel. The content-addressable memory array is composed of multiple content-addressable memories arranged in a row. Each content-addressable memory consists of two complementary nonlinear memristors and realizes one bit of data storage by combining high and low resistance states. The content-addressable memories in each row are connected to the same matching line and represent one piece of stored data.

[0008] The configurable current / voltage sensing module is used to convert the matching degree, represented by analog current or voltage, input on each matching line into a digital signal and return the digital signal to the main processor.

[0009] The main processor is used to analyze the digital signal to obtain the matching result of each stored data and the search data.

[0010] In one embodiment, the nonlinear memristor is a resistive random access memory, a ferroelectric memory, a phase-change memory, a self-selected transfer torque-magnetic random access memory, a NOR Flash device, or a NAND Flash device.

[0011] In one embodiment, the content-addressable memory array is structured as a two-dimensional planar structure or a three-dimensional stacked structure.

[0012] In one embodiment, the two-dimensional planar structure includes a two-dimensional crossbar structure, and the three-dimensional stacked structure includes a three-dimensional horizontal stacked structure and a three-dimensional vertical stacked structure.

[0013] In one embodiment, a discharge transistor is connected to a matching line that is common to each line of content-addressable memory. The discharge transistor is used for initialization before the search phase.

[0014] In one embodiment, the input voltage drive module consists of a pair of complementary 1-bit digital-to-analog converters, with each bit of the search data represented by a pair of complementary 1-bit digital-to-analog converters.

[0015] In one embodiment, when the search data is "1", the paired complementary 1-bit digital-to-analog converters output V. S A voltage of magnitude 0; when searching for data "0", the paired complementary 1-bit digital-to-analog converters output 0 and V respectively. S Voltage magnitude, V S This is the search voltage for the content-addressable memory array.

[0016] In one embodiment, the configurable current / voltage sensing module is configured by the main processor to a current or voltage sensing mode according to search requirements.

[0017] In one embodiment, the configurable current / voltage sensing module includes multiple configurable current / voltage sensing units, each of which is connected to a matching line. Each configurable current / voltage sensing unit includes a transimpedance amplifier, a sensitive amplifier, and two two-to-one switches. The sensing mode of each configurable current / voltage sensing unit is achieved by the main processor controlling the switching of the two two-to-one switches.

[0018] Secondly, the present invention also provides a parallel data search method based on the above-mentioned reconfigurable content addressable memory system, comprising the following steps:

[0019] (1) Determine the search requirements for each row of data, and configure the sensing mode of each configurable current / voltage sensing unit through the main processor according to the search requirements; where, when it is necessary to implement the fuzzy filtering search function, configure the corresponding configurable current / voltage sensing unit as the current sensing mode; when it is necessary to implement the precise search function, configure the corresponding configurable current / voltage sensing unit as the voltage sensing mode.

[0020] (2) Initialization operation: turn on all discharge transistors to discharge the matching line of each row to ground; after initialization, turn off all discharge transistors.

[0021] (3) The search data is transmitted to the voltage drive module, which is composed of a pair of complementary 1-bit digital-to-analog converters, through the main processor. The voltage drive module converts the data into voltage signals and inputs them in parallel into each row of the content addressable memory array and each stored data. The data is compared and matched at the same time. Each matching line outputs the matching degree in parallel, represented by voltage or current, according to the sensing mode.

[0022] (4) The configurable current / voltage sensing module uses a transimpedance amplifier to convert the current on the matching line into voltage according to the sensing mode, and then compares it through a sensitive amplifier or directly uses a sensitive amplifier to obtain the digital output result "0" or "1" of the sensitive amplifier. If it is a voltage sensing mode, it represents "match" or "mismatch". If it is a current sensing mode, it represents "high similarity" or "low similarity".

[0023] (5) The main processor analyzes the matching results of each stored data and search data based on the digital results output by the sensitive amplifier.

[0024] The reconfigurable content-addressable memory system and method provided by this invention employs a content-addressable memory composed of two complementary nonlinear memristors. By utilizing the reverse cutoff characteristic of the nonlinear memristors, array leakage current can be effectively suppressed. Furthermore, through a configurable current / voltage sensing module, both precise lookup and fuzzy filtering search functions can be implemented within the same content-addressable memory array. This enables system reconfigurability without introducing additional arrays and circuits, effectively reducing system area and power consumption. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of a reconfigurable content addressable memory system provided in an embodiment of the present invention;

[0026] Figure 2This is a circuit diagram of data search provided in an embodiment of the present invention;

[0027] Figure 3 This is a current-voltage curve of a nonlinear memristor provided in an embodiment of the present invention;

[0028] Figure 4 This is the result of reading the resistance values ​​of 150 devices using a nonlinear memristor provided in an embodiment of the present invention at +2V and -2V read voltages;

[0029] Figure 5 This is a schematic diagram illustrating the voltage input and data storage format, as well as matching and mismatch scenarios, provided by an embodiment of the present invention.

[0030] Figure 6 This is a circuit structure diagram of a current sensing mode and a voltage sensing mode provided in an embodiment of the present invention;

[0031] Figure 7 This is a graph showing the relationship between the reading voltage and the matching degree provided in one embodiment of the present invention;

[0032] Figure 8 This is a graph showing the relationship between the reading current and the matching degree provided in one embodiment of the present invention;

[0033] Figure 9 This is an example of reconfigurable fuzzy filtering and precise search in a reconfigurable content addressable memory system provided by an embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] Figure 1 This is a schematic diagram of the structure of a reconfigurable content addressable memory system provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the system includes an input voltage drive module 10, a content addressable memory array 20, a configurable current / voltage sensing module 30, and a main processor 40.

[0036] The configurable current / voltage sensing module 30 includes two sensing modes: current and voltage. The current sensing mode corresponds to the fuzzy filtering search function, where the current difference between matching degrees is evenly distributed. A reference current can be set between any adjacent matching degrees, and a comparison is made to determine if the similarity is high. The voltage sensing mode corresponds to the precise search function, where the voltage difference between matching degrees is uneven, and the voltage difference between a perfect match and a mismatch is the largest and easily distinguishable. A reference voltage is set between these two, and a comparison is made to determine if a perfect match is achieved. Specifically, the sensing mode of the configurable current / voltage sensing module 30 can be configured according to actual search requirements, thereby switching between the two search functions as needed.

[0037] In this embodiment, the input voltage driving module 10 is used to convert the search data input by the main processor 40 into an analog voltage signal and use it as the voltage input of the content addressable memory array for searching.

[0038] Content-addressable memory array 20 is used to store data and compare the stored data with search data input in the form of analog voltage in parallel. Then, according to the sensing mode, it outputs the matching degree in the form of analog current or voltage to configurable current / voltage sensing module 30 in parallel. That is, when the sensing mode is current sensing mode, content-addressable memory array 20 outputs the matching degree in the form of analog current in parallel, and when the sensing mode is voltage sensing mode, content-addressable memory array 20 outputs the matching degree in the form of analog voltage in parallel.

[0039] Specifically, the content-addressable memory array 20 provided in this embodiment is composed of multiple content-addressable memories arranged together. Each content-addressable memory consists of two complementary nonlinear memristors and uses a combination of high and low resistance states to realize one bit of data storage. That is, when storing data "0", the two complementary nonlinear memristors are adjusted to high resistance and low resistance states respectively, and when storing data "1", the two complementary nonlinear memristors are adjusted to low resistance and high resistance states respectively. Moreover, the content-addressable memories in each row are connected to the same matching line and represent one piece of stored data.

[0040] It should be noted that the nonlinear memristor mentioned in this embodiment can be a resistive random access memory, ferroelectric memory, phase-change memory, self-selected transfer torque-magnetic random access memory, NOR Flash device, or NAND Flash device; this embodiment is not limited to any of these. The structure of the content-addressable memory array 20 mentioned in this embodiment can be a two-dimensional crossbar structure or other two-dimensional planar structure array, a three-dimensional horizontal stacked structure, a three-dimensional vertical stacked structure, or other three-dimensional stacked structure; this embodiment is not limited to any of these.

[0041] Furthermore, in this embodiment, a discharge transistor can be connected to the matching line that is connected to each row of content addressable memory in the content addressable memory array 20. The discharge transistor is controlled by the signal DCH and is used to initialize the matching line to ground before the search phase.

[0042] The configurable current / voltage sensing module 30 is used to convert the input matching degree, represented by analog current or voltage, into a digital signal and return the digital signal to the main processor.

[0043] The main processor 40 is used to analyze the digital signal to obtain the matching result of each stored data and the search data. Specifically, the main processor 40 provided in this embodiment can be a processor commonly used in the art, such as a DSP chip or an FPGA chip, etc., and this embodiment is not limited thereto.

[0044] The reconfigurable content-addressable memory system provided in this embodiment uses a content-addressable memory composed of two complementary nonlinear memristors. By utilizing the reverse cutoff characteristic of the nonlinear memristors, the array leakage current can be effectively suppressed. Through a configurable current / voltage sensing module, both precise lookup and fuzzy filtering search functions can be implemented in the same content-addressable memory array. This enables the reconfigurability of the system without introducing additional arrays and circuits, effectively reducing the system's area and power consumption.

[0045] In one embodiment, the input voltage driving module provided by the present invention can be composed of pairs of complementary 1-bit digital-to-analog converters (DACs), where each bit of the search data is represented by a pair of complementary 1-bit DACs. Specifically, when the search data is "1", the pair of complementary 1-bit DACs output V. S And a voltage of magnitude 0; when searching for data "0", the paired complementary 1-bit digital-to-analog converter outputs 0 and V respectively. S Voltage magnitude, V S This is the search voltage for the content-addressable memory array.

[0046] In one embodiment, the sensing mode switching of the configurable current / voltage sensing module provided by the present invention can be controlled by the main processor 40. The configurable current / voltage sensing module 30 includes multiple configurable current / voltage sensing units, each of which is connected to a matching line. Each configurable current / voltage sensing unit includes a transimpedance amplifier (TIA), a sensitive amplifier (SA), and two two-to-one switches. The sensing mode of each configurable current / voltage sensing unit is realized by the main processor 40 controlling the switching of the two two-to-one switches.

[0047] Specifically, the principle behind the configurable current / voltage sensing module 30 provided in this embodiment for implementing both precise search and fuzzy filtering search functions is as follows: The current sensing mode corresponds to the fuzzy filtering search function. At this time, the current difference between each matching degree is evenly distributed, and the voltage after TIA linear conversion is also linearly distributed. Therefore, an SA reference voltage can be set between any two adjacent matching degrees, and the similarity is determined after SA comparison. The voltage sensing mode corresponds to the precise search function. At this time, the voltage difference between each matching degree is uneven, and the voltage difference between complete matching and non-matching is the largest and easy to distinguish. The SA reference voltage is set between the two, and the complete matching is determined after SA comparison.

[0048] Based on the aforementioned structural extensions of each module in this invention, the parallel data search method for the reconfigurable content-addressable memory system provided by this invention is as follows:

[0049] Step 1: First, determine the search requirements for each row of data. Based on these requirements, configure the sensing modes of each configurable current / voltage sensing unit via the main processor. Specifically, when fuzzy filtering search is required, configure the corresponding configurable current / voltage sensing unit to current sensing mode; when precise search is required, configure the corresponding configurable current / voltage sensing unit to voltage sensing mode.

[0050] Step 2: Initialization operation. Turn on the discharge transistor to discharge the matching lines of each row to ground; after initialization, turn off the discharge transistor. Specifically, the discharge transistor can be turned on and off by the main processor sending a DCH signal to it; that is, when the DCH signal goes high, the discharge transistor is turned on, and vice versa.

[0051] Step 3: The main processor transmits the search data to a voltage drive module composed of paired complementary 1-bit digital-to-analog converters. This converts the data into voltage signals, which are then input in parallel to each row and each stored data entry in the Content Addressable Memory (COM) array. Simultaneously, these signals are compared and matched. When data matches, no current flows into or out of the matching line, and the matching line voltage does not increase. When data does not match, current flows into the matching line, and the greater the mismatch, the greater the current and the higher the matching line voltage. All matching lines in the COM array output the matching degree, represented by voltage or current, in parallel according to the sensing mode; this is the Hamming distance.

[0052] Step 4: The configurable current / voltage sensing module uses TIA to convert the current on the matching line into voltage according to the sensing mode, and then compares it through SA or directly uses SA to obtain the digital output result of SA, "0" or "1". If it is voltage sensing mode, it represents "match" or "mismatch"; if it is current sensing mode, it represents "high similarity" or "low similarity".

[0053] Step 5: The main processor analyzes the numerical results output by SA to obtain the matching results of each stored data and search data.

[0054] Overall, the above technical solutions conceived by this invention can achieve the following beneficial effects compared with the prior art: (1) The reconfigurable content addressable memory system provided by this invention can match and search for search data and stored data in parallel and output results in a single search operation, with extremely high parallelism; (2) The reconfigurable content addressable memory system provided by this invention can realize two search functions, fuzzy filtering or precise search, by switching the sensing mode of the configurable current / voltage sensing module according to search requirements, thereby realizing the reconfigurability of the system without introducing additional arrays and circuits, reducing the area and power consumption of the system; (3) The reconfigurable content addressable memory system provided by this invention utilizes the reverse cutoff characteristic of nonlinear memristors to effectively suppress the influence of leakage current during the search, accelerate the current charging speed, and reduce the power consumption generated by leakage current.

[0055] The present invention will be described in detail below with reference to specific embodiments:

[0056] Example 1

[0057] Content-addressable memory system array and peripheral circuitry are the main components, such as Figure 2 As shown, it mainly includes:

[0058] The system comprises an input voltage drive module, a content-addressable memory array, and a configurable current / voltage sensing module. The input voltage drive module mainly consists of a 1-bit DAC; the content-addressable memory array mainly consists of content-addressable memory cells composed of two nonlinear memristors, with a discharge transistor for initialization in each row; and the configurable current / voltage sensing module mainly consists of a transimpedance amplifier (TIA), a sensitive amplifier (SA), and a two-to-one switch.

[0059] The sensing mode configuration of the configurable current / voltage sensing module is mainly achieved by switching between two two-to-one switches. The TIA is used to linearly convert the current into voltage, and its amplification factor can be changed. The sensitive amplifier is used to compare the input voltage and the reference voltage to obtain a digital output result of "0" or "1".

[0060] Example 2

[0061] The current-voltage characteristic curves and forward and reverse read voltage resistance values ​​of the nonlinear resistive random access memory are as follows:

[0062] Figure 3This is a current-voltage curve of a nonlinear memristor provided in an embodiment of the present invention. The device exhibits reverse cutoff, or self-rectification characteristics. When the input voltage is negative, the current is almost zero, and when the input voltage is positive, it exhibits obvious high and low resistance states.

[0063] Figure 4 This invention provides a nonlinear memristor with a resistance distribution when the read voltage is ±2V. The nonlinear memristor has a stable distribution of high and low resistance states under forward voltage, and the ratio of the high and low resistance values ​​exceeds 1000. Under reverse voltage, it maintains a high resistance value, regardless of whether it is in a high or low resistance state.

[0064] Example 3

[0065] Figure 5 This is a schematic diagram illustrating the storage and search methods of a content-addressable memory (MAP) cell and different matching scenarios according to an embodiment of the present invention. A MAP consists of two nonlinear memristors, R0 and R1. When storing "0", R0 and R1 are in high-resistance and low-resistance states, respectively; when storing "1", R0 and R1 are in low-resistance and high-resistance states, respectively. The search is implemented by two complementary 1-bit DACs. When searching for "0", 0 and V are applied respectively. S The voltage, when searching for "1", is V applied respectively. S The voltage of 0 and 0, where V S This is the search voltage for the content-addressable memory array; when the stored data and the search data match, current flows into the matching line between R0 and R1 to charge it, and when they do not match, almost no current flows in or out.

[0066] Example 4

[0067] The methods for implementing both exact match and fuzzy filter search modes are as follows:

[0068] Figure 6 This is a circuit structure diagram of two search modes provided in an embodiment of the present invention. The fuzzy filtering mode requires the sensing circuit to be configured as a current sensing mode, that is, both two-to-one switches are connected to the TIA, the current is converted into voltage and then compared with the SA. At this time, the matching line is equivalent to grounding. The precise search mode is configured as a voltage sensing mode, the two two-to-one switches are directly connected, and the voltage is directly compared with the SA. At this time, the matching line is equivalent to an open circuit.

[0069] Figure 7 This is a graph showing the relationship between read voltage and matching degree in the precise search mode provided by an embodiment of the present invention. The voltage difference between 0-8 mismatches is uneven, and the perception margin between full match and mismatch is large (nearly 1.3V). The reference voltage of SA is set between match and mismatch, making it easy to distinguish whether it is a complete match.

[0070] Figure 8 This is a graph showing the relationship between read current and matching bit length (or Hamming distance) in the fuzzy filtering mode provided by this embodiment of the invention. The current difference between 0-8 mismatches is uniform, and the sensing margin is small. The SA reference voltage, equivalent to a reference current, can be set between any two adjacent mismatches as a filtering threshold. The magnitude of the equivalent reference current is determined by the SA reference voltage and the amplification factor of the TIA. A small Hamming distance between the stored data and the searched data indicates high similarity, and vice versa.

[0071] Example 5

[0072] The following is an example implementation of data lookup in a content-addressable memory system:

[0073] Figure 9 This is an example of searching for "0110" data according to an embodiment of the present invention. The storage array data are "1011", "0110", "1110", and "0111". The second and third rows use a precise matching mode based on read voltage, while the first and fourth rows use a fuzzy filtering mode based on read current. The fuzzy filtering is set so that a mismatch bit length (Hamming distance) > 1 indicates low similarity. The TIA amplification factor is set to 1 GΩ, the bias voltage is 0.5V, and the SA reference voltage is set to 0.65V. During the search phase, the search data is processed by paired complementary 1-bit DACs according to... Figure 5 The voltage application method shown is input into the array, and the current is converted into voltage or the voltage is obtained directly as 0.74V, 0.02V, 1.31V and 0.58V respectively. After comparison by SA, the digital outputs "1", "0", "1" and "0" are obtained respectively. Combined with the search mode, they represent low similarity, matching, mismatch and high similarity respectively.

[0074] The reconfigurable content addressable memory system and method provided by this invention can achieve high-parallel data search within the memory, reduce data transmission and processing, and improve search efficiency; it can also realize reconfigurable design and mode switching of two search modes, fuzzy filtering and precise search, without introducing redundant arrays and peripheral circuits, which greatly improves the versatility and space reusability of the search system.

[0075] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A reconfigurable content addressable memory system, characterized by, It includes an input voltage driving module, a content addressable memory array, a configurable current / voltage sensing module and a main processor. The configurable current / voltage sensing module is used to switch between current or voltage sensing modes according to search requirements. The current and voltage sensing modes correspond to fuzzy filtering and precise search functions, respectively. The input voltage driving module is used to convert the search data input by the main processor into an analog voltage signal and output it to the content addressable memory array. The content-addressable memory array is used to store data and compare the stored data with search data input in the form of analog voltage in parallel. Then, according to the sensing mode, it outputs the matching degree represented by analog current or voltage to the configurable current / voltage sensing module in parallel. The content-addressable memory array is composed of multiple content-addressable memories arranged in a row. Each content-addressable memory consists of two complementary nonlinear memristors and realizes one bit of data storage by combining high and low resistance states. The content-addressable memories in each row are connected to the same matching line and represent one piece of stored data. The configurable current / voltage sensing module is used to convert the matching degree, represented by analog current or voltage, input on each matching line into a digital signal and return the digital signal to the main processor. The main processor is used to analyze the digital signal to obtain the matching result of each stored data and the search data.

2. The reconfigurable content addressable memory system of claim 1, wherein, The nonlinear memristor is a resistive random access memory, ferroelectric memory, phase change memory, self-selected transfer torque-magnetic random access memory, NOR Flash device, or NAND Flash device.

3. The reconfigurable content addressable memory system according to claim 1 or 2, characterized in that, The content-addressable memory array has a two-dimensional planar structure or a three-dimensional stacked structure.

4. The reconfigurable content addressable memory system of claim 3, wherein, The two-dimensional planar structure includes a two-dimensional crossbar structure, and the three-dimensional stacked structure includes a three-dimensional horizontal stacked structure and a three-dimensional vertical stacked structure.

5. The reconfigurable content addressable memory system of claim 1, wherein, Each line of content-addressable memory has a matching line connected to it, and the discharge transistor is used for initialization before the search phase.

6. The reconfigurable content addressable memory system according to claim 5, characterized in that, The input voltage drive module consists of a pair of complementary 1-bit digital-to-analog converters, and each bit of the search data is represented by a pair of complementary 1-bit digital-to-analog converters.

7. The reconfigurable content addressable memory system of claim 6, wherein, When searching for data "1", the paired complementary 1-bit digital-to-analog converters output V. S And a voltage of magnitude 0; when searching for data "0", the paired complementary 1-bit digital-to-analog converters output 0 and V respectively. S Voltage magnitude, V S This is the search voltage for the content-addressable memory array.

8. The reconfigurable content addressable memory system of claim 7, wherein, The configurable current / voltage sensing module is configured to a current or voltage sensing mode by the main processor according to the search requirements.

9. The reconfigurable content addressable memory system of claim 8, wherein, The configurable current / voltage sensing module includes multiple configurable current / voltage sensing units, each of which is connected to a matching line. Each configurable current / voltage sensing unit includes a transimpedance amplifier, a sensitive amplifier, and two two-to-one switches. The sensing mode of each configurable current / voltage sensing unit is achieved by the main processor controlling the switching of the two two-to-one switches.

10. A parallel data search method based on the reconfigurable content addressable memory system of claim 9, characterized in that, Includes the following steps: (1) Determine the search requirements for each row of data, and configure the sensing mode of each configurable current / voltage sensing unit through the main processor according to the search requirements; where, when it is necessary to implement the fuzzy filtering search function, configure the corresponding configurable current / voltage sensing unit as the current sensing mode; when it is necessary to implement the precise search function, configure the corresponding configurable current / voltage sensing unit as the voltage sensing mode. (2) Initialization operation: turn on all discharge transistors to discharge the matching line of each row to ground; after initialization, turn off all discharge transistors. (3) The search data is transmitted to the voltage drive module, which is composed of a pair of complementary 1-bit digital-to-analog converters, through the main processor. The voltage drive module converts the data into voltage signals and inputs them in parallel into each row of the content addressable memory array and each stored data. The data is compared and matched at the same time. Each matching line outputs the matching degree in parallel, represented by voltage or current, according to the sensing mode. (4) The configurable current / voltage sensing module converts the current on the matching line into voltage using a transimpedance amplifier according to the sensing mode, and then compares it with a sensitive amplifier or directly compares it with a sensitive amplifier to obtain the digital output result "0" or "1" of the sensitive amplifier. If it is a voltage sensing mode, it represents "match" or "mismatch". If it is a current sensing mode, it represents "high similarity" or "low similarity". (5) The main processor analyzes the matching results of each stored data and search data based on the digital results output by the sensitive amplifier.

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