In-memory search device

Abstract

The invention provides an in-memory search apparatus. The apparatus includes a plurality of first memory cell strings, a controller, and a sensing circuit. The first memory cell strings are commonly coupled to a first common bit line. Each first storage unit string comprises a plurality of first data storage layers. The first data storage layers respectively comprise a plurality of first memory cell pairs, and the first memory cell pairs are respectively coupled to a plurality of first word line pairs. The controller selects at least one of the first data storage layers as at least one selected data storage layer and provides search data to at least one selected word line pair corresponding to the at least one selected data storage layer. The sensing circuit senses a current of the first common bit line to generate a search result.

Description

Technical Field

[0001] The present invention relates to a memory search device, and more particularly to a memory search device capable of improving search efficiency. Background Art

[0002] With the advancement of electronic technology, the development of artificial intelligence is becoming more and more mature. As a result, the demand for searching a large amount of data is generated. Accordingly, an in-memory search device is introduced. As the amount of data to be searched increases, how to apply the in-memory search device to perform data search actions on a large amount of data has become an important issue for those skilled in the art. Summary of the invention

[0003] The present invention provides a memory search device, which can perform hierarchical data search on the memory and improve the efficiency of the data search action.

[0004] The memory search device of the present invention includes a plurality of first storage cell strings, a controller, and a sensing circuit. The first storage cell strings are commonly coupled to a first common bit line. Each first storage cell string includes a plurality of first data storage layers. The first data storage layers respectively include a plurality of first storage cell pairs, and the first storage cell pairs are respectively coupled to a plurality of first word line pairs. The controller is coupled to the first storage cell strings, selects one of the first data storage layers as at least one selected data storage layer, and provides search data to at least one selected word line pair corresponding to at least one selected data storage layer. The sensing circuit is coupled to the first common bit line, and senses the current of the first common bit line to generate search results.

[0005] Based on the above, the memory search device of the present invention can divide the memory into multiple data storage layers. When performing a data search operation, the data search operation can be performed on one or more data storage layers, which can speed up the data search efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic diagram of a memory search device according to an embodiment of the present invention;

[0007] Figure 2 The present invention Figure 1 A schematic diagram of another implementation of the memory search device of the embodiment;

[0008] Figure 3 The present invention Figure 1 A schematic diagram of another implementation of the memory search device of the embodiment;

[0009] Figure 4A as well as Figure 4B is a schematic diagram of a data search action of a memory search device according to an embodiment of the present invention;

[0010] FIG. 5A to FIG. 5C is a schematic diagram of an in-memory search device and an implementation method of a data search action according to another embodiment of the present invention;

[0011] FIG. 6A to FIG. 6D It is a schematic diagram of multiple execution modes of a data search action for a selected data storage layer in a memory search device according to an embodiment of the present invention;

[0012] Description of reference numerals:

[0013] 100, 500: Search device in memory

[0014] 110, 120, 411~41(N), 511~5AN: storage unit string

[0015] 130: Controller

[0016] 140: Sensor

[0017] 501: Sensors and encoders

[0018] BL, BL1~BLA: common bit line

[0019] Is1, IA, IB: current

[0020] M1~MZ: storage unit

[0021] MC1, MC2: storage unit

[0022] SD: Search Data

[0023] SL1~SLA, SLB, SL11~SLN1, SLA1~SLAN, 610: Select the data storage layer

[0024] SSL1, SSL2, GSL, CSL: Select signal

[0025] SW1, SW2, SW(N): Selection switch

[0026] VA, VB, Vmax, Vmin: Search voltage

[0027] Vg1, Vg2: bias voltage

[0028] VH1~VH4: voltage

[0029] Vpass: pass voltage

[0030] VT_A, VT_B: Voltage curve

[0031] VT1, VT4: Voltage distribution

[0032] WL11~WL2(Z), WL1_1~WL1_512, WL2_1~WL2_512, WL3_1~WL3_512, WL4_1~WL4_512 , WL89_1~WL89_512, WL90_1~WL90_512, WL89_1~WL89_512, WL90_1~WL90_512: word line

[0033] X, Y, Z: Axis DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0035] Please refer to Figure 1 , Figure 1 1 is a schematic diagram of an in-memory search device according to an embodiment of the present invention. The in-memory search device 100 includes a plurality of memory cell strings 110, 120, a controller 130, and a sensor 140. The memory cell strings 110, 120 are commonly coupled to a common bit line BL. The memory cell string 110 is coupled to the common bit line BL through a selection switch SW1, and the memory cell string 120 is coupled to the common bit line BL through a selection switch SW2. The selection switches SW1 and SW2 are respectively controlled by selection signals SSL1 and SSL2 to be turned on or off. The memory cell strings 110, 120 may include a plurality of memory cells. Taking the memory cell string 110 as an example, the memory cell string 110 includes a plurality of memory cells M1-MZ connected in series. The memory cells M1-MZ may be inverse-and-type flash memory cells.

[0036] Each of the memory cell strings 110 and 120 has a plurality of memory cells coupled in series. The plurality of memory cells on the memory cell string 110 are respectively coupled to a plurality of word lines WL11 to WL1 (Z). The plurality of memory cells on the memory cell string 120 are respectively coupled to a plurality of word lines WL21 to WL2 (Z). In the present embodiment, the plurality of memory cells on each of the memory cell strings 110 and 120 can be grouped in pairs. The two memory cells in a single memory cell string 110 and 120 can form a data storage layer. Also taking the memory cell string 110 as an example, the memory cells M1 and M2 can form a data storage layer; the memory cells M3 and M4 can form another data storage layer; ...; the memory cells MZ-1 and MZ can form the last data storage layer in the icon.

[0037] In other embodiments of the present invention, in a single memory cell string, two non-adjacent flash memory cells may also be used to form a data storage layer. Figure 1 The above-mentioned method is only an illustrative example and is not intended to limit the scope of the present invention.

[0038] On the other hand, the controller 130 is coupled to the memory cell strings 110 and 120. When performing a data search operation, the controller 130 may select at least one of the data storage layers in the memory cell strings 110 and 120 as one or more selected data storage layers. Figure 1 In the example, when performing a data search operation, the controller 130 may select the data storage layer formed by the memory cells M1 and M2 in the memory cell string 110 as the selected data storage layer SL1. Furthermore, the controller 130 may select two memory cells in the memory cell string 120 corresponding to the selected data storage layer SL1 as the selected data storage layer SL2.

[0039] In addition, the controller 130 may provide search data SD to a selected word line pair (including word lines WL11 and WL12) on the selected data storage layer SL1 and a selected word line pair (including word lines WL21 and WL22) on the selected data storage layer SL2, so as to perform a data search operation for the search data SD on the selected data storage layers SL1 and SL2. When the search data SD is digital data, the controller 130 may provide a plurality of bits of the search data SD to the word lines WL11 and WL12 on the selected data storage layer SL1 and the word lines WL21 and WL22 on the selected data storage layer SL2, respectively. When the search data SD is analog data, the controller 130 may provide a plurality of analog component voltages of the search data SD to the word lines WL11, WL12, WL21 and WL22, respectively.

[0040] The controller 130 of the embodiment of the present invention may be constructed by using a digital circuit, or may be implemented by using a memory controller well known to those skilled in the art, without any specific limitation.

[0041] In the above-mentioned data search action, the storage cells in the data storage layers SL1 and SL2 are selected, and can be compared with the search data SD received on the word lines WL11, WL12, WL21 and WL22 according to the stored data, and used to generate search results. In the present embodiment, the storage cells in the data storage layers SL1 and SL2 are selected, and a current can be generated on the common bit line BL according to the comparison action between the stored data and the search data SD. In the present embodiment, the sensor 140 coupled to the common bit line BL can generate search results by sensing the current on the common bit line BL. It is worth mentioning that in the present embodiment, the data similarity represented by the search result is positively correlated with the current on the common bit line BL.

[0042] Please refer to the following Figure 2 , Figure 2 The present invention Figure 1A schematic diagram of another implementation of the memory search device of the embodiment. Figure 2 In the embodiment, two data storage layers in the memory cell string 110 are selected as the selected data storage layers SL1 and SL3. Correspondingly, two data storage layers in the memory cell string 120 are selected as the selected data storage layers SL2 and SL4. When performing a data search operation, the search data can be synchronously provided to the two selected word line pairs (including word lines WL11, WL12, WL13, and WL14) corresponding to the selected data storage layers SL1 and SL3 and the two selected word line pairs (including word lines WL21, WL22, WL23, and WL24) corresponding to the selected data storage layers SL2 and SL4. In this way, relative to Figure 1 In the implementation mode, data search actions for relatively large size data can be performed and the bandwidth of the data search actions can be effectively improved.

[0043] It is worth mentioning that, in this embodiment, the selected data storage layers SL1 and SL3 may be adjacent data storage layers. In other embodiments of the present invention, the selected data storage layers may also be two data storage layers that are not adjacent to each other. Figure 2 The implementation methods described are merely illustrative examples and are not intended to limit the scope of implementation of the present invention.

[0044] Please refer to the following Figure 3 , Figure 3 The present invention Figure 1 A schematic diagram of another implementation of the memory search device of the embodiment. Figure 3 In the embodiment, all the data storage layers in the memory cell string 110 can be selected at the same time to serve as the selected data storage layers SL1 -SLA. Correspondingly, all the data storage layers in the memory cell string 120 can be selected at the same time to serve as the selected data storage layers SL2 -SLB.

[0045] When performing a data search operation, the search data can be synchronously provided to the selected word line pairs (including word lines WL11-WL1(Z)) corresponding to the selected data storage layers SL1-SLA and the selected word line pairs (including word lines WL21-WL2(Z)) corresponding to the selected data storage layers SL2-SLB. Figure 1 , 2 In the implementation mode, data search actions for larger size data can be performed, effectively improving the bandwidth of the data search action.

[0046] Please refer to the following Figure 4A as well as Figure 4B , Figure 4A as well as Figure 4B FIG. 1 is a schematic diagram of a data search operation of a memory search device according to an embodiment of the present invention. Figure 4A as well as Figure 4B In the embodiment, the in-memory search device 400 includes a plurality of memory cell strings 411-41(N). The memory cell strings 411-41(N) are respectively coupled to a common bit line BL through selection switches SW1-SW(N). The selection switches SW1-SW(N) are respectively controlled by selection signals SSL1-SSLN. When performing a data search operation, the selection switches SW1-SW(N) can be simultaneously turned on according to the selection signals SSL1-SSLN.

[0047] In this embodiment, if Figure 4A As shown, in the first interval of the data search operation, a corresponding data storage layer in the memory cell strings 411-41(N) is simultaneously set as the selected data storage layer SL11-SLN1. The controller can also provide multiple components of the search data to the selected word line pair (including word lines WL1_1-WL1_512 and word lines WL2_1-WL2_512) on the selected data storage layer SL11-SLN1. In this way, the memory search device 400 can complete the first layer of data search operation.

[0048] Incidentally, in the data search operation, the memory search device 400 can provide a pass voltage Vpass to a plurality of word lines of unselected data storage layers. In addition, each memory cell string 411 ˜ 41 (N) has a plurality of switches controlled by the selection signals GSL and CSL.

[0049] Then, in Figure 4B In the second interval of the data search operation, another corresponding data storage layer in the memory cell strings 411-41(N) is simultaneously set as the selected data storage layer SL12-SLN2. The controller can also provide multiple components of the search data to the selected word line pair (including word lines WL3_1-WL3_512 and word lines WL4_1-WL4_512) on the selected data storage layer SL12-SLN2. In this way, the in-memory search device 400 can complete the second layer data search operation.

[0050] according to Figure 4A as well as Figure 4B By analogy with the description of , the memory search device 400 can select each data storage layer in the storage unit string 411-41(N) one by one as the selected data storage layer according to the time sequence, and perform the data search operation accordingly.

[0051] It is worth mentioning that in other embodiments of the present invention, in the same time interval of the data search operation, corresponding to each storage unit string, multiple data storage layers can also be selected as selected data storage layers, and the data search operation can be performed synchronously. In this way, the efficiency of the data search operation can be effectively improved.

[0052] Please refer to the following FIG. 5A to FIG. 5C , FIG. 5A to FIG. 5C FIG. 1 is a schematic diagram of another embodiment of a memory search device and a data search operation implementation method of the present invention. Figure 5A In the memory search device 500, a plurality of memory cell strings 511-5AN and a sensor and encoder 501 are included. The memory cell strings 511-51N are commonly coupled to a common bit line BL1 through the selection switches they have; the memory cell strings 521-52N are commonly coupled to a common bit line BL2 through the selection switches they have; ...; the memory cell strings 5A1-5AN are commonly coupled to a common bit line BLA through the selection switches they have. In the present embodiment, the memory cell strings 511-5AN can be arranged into a cube structure. Among them, in the memory search device 500, each common bit line BL1-BLA extends along the Y-axis direction, each word line extends along the X-axis direction, and a plurality of memory cells of each memory cell string 511-5AN are coupled in series along the Z-axis direction. In addition, each memory cell string 511-5AN has a plurality of switches controlled by selection signals GSL and CSL.

[0053] The sensor and encoder 501 is coupled to the common bit lines BL1-BLA. The sensor in the sensor and encoder 501 is used to sense the current on the common bit lines BL1-BLA to generate search results. The encoder in the sensor and encoder 501 is used to encode the search results to generate encoded search results.

[0054] Incidentally, the sensor in the sensor and encoder 501 may be a sense amplifier and may be implemented using a sense amplifier circuit known to those skilled in the art. The encoder in the sensor and encoder 501 may be a digital circuit and may be disposed in a page buffer.

[0055] When the in-memory search device 500 performs a data search operation, in a single time interval, the in-memory search device 500 can set a data storage layer corresponding to a position in each storage cell string 511-5AN as a selected data storage layer. In this embodiment, the in-memory search device 500 can set selected data storage layers SL11-SL1N for storage cell strings 511-51N, respectively; set selected data storage layers SL21-SL2N for storage cell strings 521-52N, respectively; ...; and set selected data storage layers SLA1-SLAN for storage cell strings 5A1-5AN, respectively.

[0056] In this embodiment, based on the mutual correspondence in position, the selected data storage layers SL11~SL1N are respectively coupled to the selected word line pairs corresponding to the selected data storage layers SL21~SL2N, and the selected data storage layers SL21~SL2N are also respectively coupled to the selected word line pairs corresponding to the selected data storage layers SLA1~SLAN.

[0057] On the other hand, in the data search operation, the search data SD can be split into multiple parts and provided to multiple selected word line pairs coupled to the selected data storage layers SL11-SLAN. The multiple selected word line pairs include word lines WL89_1-WL89_512 and word lines WL90_1-WL90_512. The word lines WL89_1-WL89_512 form multiple word line pairs with the word lines WL90_1-WL90_512.

[0058] In addition, the word lines of the unselected data storage layers receive the pass voltage Vpass.

[0059] exist Figure 5A In the data search operation, the number of selected data storage layers of each memory cell string 511-5AN is 1 (n=1). In addition, in the search operation, the memory search device 500 can sequentially set a data storage layer of each memory cell string 511-5AN in different time intervals according to the time sequence through the controller to obtain a selected data storage layer, and then transmit the search data SD to the multiple selected word line pairs of the selected data storage layer to perform the data search operation.

[0060] exist Figure 5B In the embodiment of the present invention, the memory search device 500 can set the number of selected data storage layers of each storage cell string 511-5AN to 2 (n=2) in the same time interval of the data search operation. The search data SD is split into multiple components and provided to multiple selected word line pairs corresponding to the multiple selected data storage layers to perform the data search operation. In the present embodiment, the selected word line pairs include word lines WL1_1-WL4_1, WL1_2-WL4_2, ..., WL1_512-WL4_512.

[0061] When executing a search operation, the search device 500 in the memory can, through a controller, sequentially set the two data storage layers of each storage cell string 511~5AN according to the time sequence in different time intervals to obtain two selected data storage layers respectively, and then transmit the search data SD to multiple selected word line pairs of the selected data storage layer to perform a data search operation.

[0062] exist Figure 5CIn the implementation mode, the memory search device 500 can simultaneously set all the data storage layers of each storage cell string 511~5AN as the selected data storage layer during the data search operation. The number of selected data storage layers n=Z / 2, and Z is the number of storage cells in each storage cell string 511~5AN. In addition, the search data SD is split into multiple components and provided to multiple selected word line pairs corresponding to multiple selected data storage layers, respectively, to perform a data search operation. In this way, the data search operation for all the stored data of the entire memory search device 500 can be completed through a one-time search operation.

[0063] According to the above description, it can be known that the memory search device 500 of the present invention can perform data search operations by setting the number n of selected data storage layers according to time requirements, which can effectively improve the efficiency of data search operations.

[0064] Please refer to the following FIG. 6A to FIG. 6D , FIG. 6A to FIG. 6D 1 is a schematic diagram of multiple execution modes of a data search action for a selected data storage layer in a memory search device according to an embodiment of the present invention. Fig. 6A In the embodiment of the present invention, the selected data storage layer 610 includes memory cells MC1 and MC2. The memory cells MC1 and MC2 may be single-level cells (SLC), multiple-level cells (MLC), triple-level cells (TLC), quad-level cells (QLC), or memory cells storing analog data. The word lines of the memory cells MC1 and MC2 may receive bias voltages Vg1 and Vg2 generated according to the search data, respectively, and generate a current Is1 reflecting the search result on the common bit line BL1 according to the search result.

[0065] exist Figure 6B In the embodiment, the selected data storage layer 610 may have storage data DAT. The storage data DAT includes a first bit D1 and a second bit D2. The storage data DAT may be encoded according to the voltage distribution VT1 to VT4 of the threshold voltages Vth1 and Vth2 of the memory cells MC1 and MC2, as shown in the following table:

[0066] Table 1:

[0067]

[0068]

[0069] When performing a data search operation, the voltage received by the gates of the memory cells MC1 and MC2 through the corresponding word lines can be one of the voltages VH1 to VH4. The voltages received by the memory cells MC1 and MC2 are generated according to the corresponding search data, wherein two bits of search data are used as an example, and the corresponding relationship between the search data and the voltages VH1 to VH4 is shown in Table 2:

[0070] Table 2:

[0071] Voltage Search Data [VH1 VH4] [0 0] [VH2 VH3] [0 1] [VH3 VH2] [1 0] [VH4 VH1] [1 1] [VH4 VH4] Wildcard Characters

[0072] When performing a data search operation, the memory cells MC1 and MC2 can generate a current Is1 on the bit line BL1 according to the voltage received by the gate and the voltage difference between the stored data.

[0073] Please refer to Figure 6C For example, the voltage distributions VT1 to VT4 are 0V to 1V, 1.5V to 2.5V, 3V to 4V, 4.5V to 5.5V, and the voltages VH1 to VH4 are 5.5V, 7V, 8.5V, and 10V. The peak values ​​of the voltage distributions VT1 to VT4 correspond to voltages of 0.5V, 2V, 3.5V, and 5V, respectively.

[0074] When performing a search operation, when the search data is

[00] , the bias voltages Vg1 and Vg2 received by the gates of the memory cells MC1 and MC2 are respectively equal to VH1 and VH4. If the storage data of the memory cells MC1 and MC2 is [0 0] at this time, the threshold voltage Vth1 of the memory cell MC1 is in the voltage distribution VT1, and the threshold voltage Vth2 of the memory cell MC2 is in the voltage distribution VT4. At this time, on the memory cell MC1, the difference between the bias voltage Vg1 and the threshold voltage Vth1 can be 5.5V-1V=4.5V. Calculated with each 1.5V as a level L, the difference between the bias voltage Vg1 and the threshold voltage Vth1 on the memory cell MC1 can be 3L. On the memory cell MC2, the difference between the bias voltage Vg2 and the threshold voltage Vth2 can be 10V-5.5V=4.5V. The difference between the bias voltage Vg2 and the threshold voltage Vth2 on the memory cell MC2 can be 3L.

[0075] That is, under this condition, when the search data matches the storage data, the memory cells MC1 and MC2 can generate a current Is1 corresponding to 3L.

[0076] When performing a search operation, when the search data is [0 0], the bias voltages Vg1 and Vg2 received by the gates of the memory cells MC1 and MC2 are respectively equal to VH1 and VH4. If the storage data of the memory cells MC1 and MC2 is [0 1] at this time, the threshold voltage Vth1 of the memory cell MC1 is in the voltage distribution VT2, and the threshold voltage Vth2 of the memory cell MC2 is in the voltage distribution VT3. The difference between the bias voltage Vg1 (=VH1) and the threshold voltage Vth1 (=VT2) of the memory cell MC1 can be 2L. The difference between the bias voltage Vg2 (=VH4) and the threshold voltage Vth2 (=VT3) of the memory cell MC2 can be 4L.

[0077] Since the memory cells MC1 and MC2 are connected in series, the selected data storage layer 610 can generate a current Is1 corresponding to 2L.

[0078] When performing a search operation, when the search data is

[00] , the bias voltages Vg1 and Vg2 received by the gates of the memory cells MC1 and MC2 are respectively equal to VH1 and VH4. If the storage data of the memory cells MC1 and MC2 is [1 0] at this time, the threshold voltage Vth1 of the memory cell MC1 is in the voltage distribution VT3, and the threshold voltage Vth2 of the memory cell MC2 is in the voltage distribution VT2. The difference between the bias voltage Vg1 (=VH1) and the threshold voltage Vth1 (=VT3) of the memory cell MC1 can be 1L. The difference between the bias voltage Vg2 (=VH4) and the threshold voltage Vth2 (=VT2) of the memory cell MC2 can be 5L. Since the memory cells MC1 and MC2 are connected in series, the selected data storage layer 610 can generate a current Is1 corresponding to 1L.

[0079] When performing a search operation, when the search data is [0 0], the bias voltages Vg1 and Vg2 received by the gates of the memory cells MC1 and MC2 are respectively equal to VH1 and VH4. If the storage data of the memory cells MC1 and MC2 is

[11] at this time, the threshold voltage Vth1 of the memory cell MC1 is in the voltage distribution VT4, and the threshold voltage Vth2 of the memory cell MC2 is in the voltage distribution VT1. The difference between the bias voltage Vg1 (=VH1) and the threshold voltage Vthl (=VT4) of the memory cell MC1 can be 0L. The difference between the bias voltage Vg2 (=VH4) and the threshold voltage Vth2 (=VT1) of the memory cell MC2 can be 6L. Since the memory cells MC1 and MC2 are connected in series, the selected data storage layer 610 can generate a current Is1 corresponding to 0L.

[0080] It is not difficult to know from the above description that the magnitude of the current Is1 generated by the data storage layer 610 is positively correlated with the similarity between the search data and the storage data.

[0081] It is worth mentioning that, as long as the number of voltage distributions and the number of bias voltages received by the memory cells MC1 and MC2 are appropriately adjusted, the selected data storage layer 610 of the embodiment of the present invention can also be used to store a variety of different levels of storage data and perform search operations for corresponding levels of search data.

[0082] exist Fig.6D In the embodiment, the storage cells MC1 and MC2 in the selected data storage layer 610 can also be used to record the simulated storage data. A data search operation is performed for the simulated search data. The threshold voltage of the storage cell MC1 can be the voltage curve VT_A, and the threshold voltage of the storage cell MC2 can be the voltage curve VT_B. The storage cells MC1 and MC2 can be independently programmed so that the threshold voltages correspond to the voltage curves VT_A and VT_B, respectively.

[0083] In addition, currents IA and IB represent channel currents of memory cells MC1 and MC2, respectively.

[0084] In this embodiment, the search data may be search voltages VA and VB, wherein the search voltages VA and VB have a relationship: VB=Vmax+Vmin-VA. Vmax and Vmin are respectively the maximum analog search voltage and the minimum analog search voltage in the search operation. In this embodiment, the maximum analog search voltage Vmax and the minimum analog search voltage Vmin are both constants, such as 9V and 0V, respectively.

[0085] When the search voltage VA is equal to 0.7V and the search voltage VB is equal to 8.3V, the memory cell MC1 does not provide current but the memory cell MC2 can provide current. When the search voltage VA is equal to 4.05V and the search voltage VB is equal to 4.95V, both the memory cell MC1 and the memory cell MC2 do not provide current. When the search voltage VA is equal to 8.52V and the search voltage VB is equal to 0.48V, the memory cell MC1 provides current but the memory cell MC2 does not provide current.

[0086] Thus, the magnitude of the current Is1 generated by the memory cells MC1 and MC2 in the selected data storage layer 610 can be used as a basis for the similarity between the stored data and the search data in the generated search results. Similarly, the magnitude of the current Is1 is positively correlated with the similarity between the stored data and the search data in the search results.

[0087] Incidentally, in other embodiments of the present invention, the threshold voltage curves of the memory cell MC1 and the threshold voltage curves of the memory cell MC2 may be interchanged. That is, the threshold voltage of the memory cell MC1 may have a voltage curve VT_B, and the threshold voltage of the memory cell MC2 may have a voltage curve VT_A.

[0088] In summary, the present invention enables the search device in the memory to set one or more data storage layers in the storage cell string as one or more selected data storage layers. And simultaneously provides multiple parts of the search data to the selected word line pairs of one or more selected data storage layers, so that the data search action can be performed synchronously for one or more selected data storage layers. In this way, the speed of the data search action in the memory can be effectively increased, and the performance of the data search action can be improved.

[0089] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A memory search device, comprising: A plurality of first memory cell strings are commonly coupled to a first common bit line, each of the first memory cell strings comprises a plurality of first data storage layers, each of the first data storage layers comprises a plurality of first memory cell pairs, and each of the first memory cell pairs is coupled to a plurality of first word line pairs; a controller coupled to the first memory cell strings, selecting at least one of the first data storage layers as at least one selected data storage layer, and providing a search data to at least one selected word line pair corresponding to the at least one selected data storage layer; and A sensing circuit is coupled to the first common bit line and senses the current of the first common bit line to generate a search result.

2. The in-memory search device according to claim 1, wherein when the number of the at least one selected data storage layer is N, the controller synchronously selects N of these first data storage layers as the at least one selected data storage layer, wherein N is a positive integer. 3 . The in-memory search device according to claim 2 , wherein the controller selects N of the first data storage layers in a time sequence as the at least one selected data storage layer. 4 . The memory search device as claimed in claim 1 , wherein the controller provides a pass voltage to a plurality of unselected word lines of a plurality of unselected data storage layers.

5. The memory search device according to claim 1, further comprising: Multiple second memory cell strings are commonly coupled to a second common bit line, each of the second memory cell strings includes multiple second data storage layers, these second data storage layers correspond to these first data storage layers respectively, these second data storage layers respectively include multiple second memory cell pairs, these second memory cell pairs and the corresponding second memory cell pairs are respectively coupled to the same first word line pairs. 6 . The in-memory search device according to claim 5 , wherein the at least one selected data storage layer comprises each selected first data storage layer and each corresponding second data storage layer. 7 . The in-memory search device as claimed in claim 1 , wherein when the search data is digital data, the controller provides a plurality of bits of the search data to at least one selected word line pair corresponding to the at least one selected data storage layer.

8. The in-memory search device as claimed in claim 1, wherein when the search data is analog data, the controller provides a plurality of analog component voltages of the search data to at least one selected word line pair corresponding to the at least one selected data storage layer. 9 . The in-memory search device as claimed in claim 1 , wherein the data similarity of the search result is positively correlated with the current of the first common bit line.

10. The memory search device according to claim 1, wherein the threshold voltage of each storage cell in each first storage cell pair is programmed within a first voltage range according to the corresponding storage data, and the controller sets the search data within a second voltage range, and the first voltage range does not overlap with the second voltage range.

11. The memory search device as claimed in claim 10, wherein the stored data is digital data or analog data.

12. The in-memory search device as claimed in claim 1, wherein the two storage units in each of the first storage unit pairs are arranged adjacently or non-adjacently.

13. The memory search device according to claim 1, further comprising: An encoder is coupled to the sensing circuit and encodes the search result to generate an encoded search result.

14. The memory search device as claimed in claim 13, wherein the encoded search result is multi-bit digital data or analog voltage. 15 . The in-memory search device according to claim 1 , wherein when the number of the at least one selected data storage layer is N, the selected data storage layers are arranged adjacent to each other or not adjacent to each other.

Images