Method for determining read voltage, data reading method, electronic device, and medium

Abstract

This application discloses a method for determining a read voltage, a data reading method, an electronic device, and a medium. The method includes acquiring distribution statistics, which include bit transition values ​​corresponding to several different voltage ranges; acquiring a preset piecewise quadratic function containing undetermined parameters, the piecewise quadratic function including a first function and a second function, the first and second functions being centrally symmetric and continuous, the undetermined parameters including the coefficients of the quadratic terms of the first and second functions; fitting the distribution statistics using the piecewise quadratic function to determine the undetermined parameters in the piecewise quadratic function; substituting the determined undetermined parameters into the first function to obtain a first voltage at the axis of symmetry of the first function, and substituting the determined undetermined parameters into the second function to obtain a second voltage at the second axis of symmetry; and determining the first voltage or the second voltage as the read voltage based on the coefficients of the quadratic terms in the undetermined parameters. Through the above method, this application can improve decoding efficiency.

Description

Technical Field

[0001] This application relates to the field of storage technology, and in particular to a method for determining read voltage, a data reading method, an electronic device, and a medium. Background Technology

[0002] In the storage field, different read voltages result in different data error rates. The optimal read voltage can provide the lowest data error rate, thereby significantly improving the data decoding success rate. Typically, to obtain the optimal read voltage for a storage device, multiple reads are performed at different voltages, and the number of data errors is counted. Then, based on the distribution statistics of the number of data errors, a quadratic function is used to fit the data to obtain the optimal read voltage. However, in some cases, the distribution statistics obtained from different read voltages may not include the optimal read voltage. Therefore, when performing quadratic function fitting, the fitted quadratic function may not have a minimum value, making it impossible to calculate the optimal read voltage corresponding to the minimum value. Summary of the Invention

[0003] The main objective of this application is to provide a method for determining the read voltage, a data reading method, an electronic device, and a medium that can obtain the optimal read voltage of a storage device, thereby reducing the data reading error rate and improving decoding efficiency.

[0004] To address the aforementioned technical problems, the first technical solution adopted in this application is: providing a method for determining a read voltage. This method includes acquiring distribution statistics, which include bit transition values ​​corresponding to several different voltage ranges; acquiring a preset piecewise quadratic function containing undetermined parameters, the piecewise quadratic function including a first function and a second function, the first and second functions being centrally symmetric and continuous, the undetermined parameters including the quadratic coefficients of the first and second functions; fitting the distribution statistics using the piecewise quadratic function to determine the undetermined parameters in the piecewise quadratic function; substituting the determined undetermined parameters into the first function to obtain a first voltage where the axis of symmetry of the first function is located, and substituting the determined undetermined parameters into the second function to obtain a second voltage where the second axis of symmetry is located; and determining the first voltage or the second voltage as the read voltage based on the quadratic coefficients in the undetermined parameters.

[0005] To address the aforementioned technical problems, the second technical solution adopted in this application is: providing a data reading method. This method includes acquiring read data; in response to a decoding failure of the read data, executing the reading voltage determination method described in the first technical solution to determine the reading voltage; and re-reading the data based on the reading voltage and performing decoding to obtain the reading result.

[0006] To address the aforementioned technical problems, the third technical solution adopted in this application is to provide an electronic device. This electronic device includes a memory and a processor. The memory stores program data, which can be executed by the processor to implement the method described in the first technical solution.

[0007] To address the aforementioned technical problems, the fourth technical solution adopted in this application is to provide a computer-readable storage medium. This computer-readable storage medium stores program data and can be executed by a processor to implement the method described in the first technical solution.

[0008] The beneficial effects of this application are as follows: After obtaining the distribution statistics of bit transition values ​​covering several different voltage ranges, a piecewise quadratic function containing undetermined parameters is used to fit the data. Since the first and second functions included in this piecewise quadratic function are centrally symmetric and continuous, the fitting process yields two axes of symmetry corresponding to the first and second functions. One axis corresponds to the maximum value of one quadratic function, and the other to the minimum value. Therefore, among the voltages containing the two axes of symmetry of the first and second functions, there must exist a voltage corresponding to the minimum value of the quadratic function. This voltage containing the minimum value of the quadratic function is the voltage where the trough of the distribution statistics is located, which is the optimal reading voltage required. Accurately calculating the optimal reading voltage and reading based on this voltage provides the lowest data error rate, improves data reliability, reduces the number of rereads, and lowers reading latency. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the bit transition unit distribution during SLC readout;

[0011] Figure 2 This is a schematic diagram of the bit transition unit distribution during SLC readout;

[0012] Figure 3 This is a schematic diagram of the bit transition unit distribution during SLC readout;

[0013] Figure 4 This is a flowchart illustrating the first embodiment of the method for determining the read voltage in this application;

[0014] Figure 5This is a flowchart illustrating the second embodiment of the method for determining the read voltage in this application;

[0015] Figure 6 This is a schematic diagram of the fitting function;

[0016] Figure 7 This is a flowchart illustrating the third embodiment of the method for determining the read voltage in this application;

[0017] Figure 8 This is a schematic diagram of the fitting function;

[0018] Figure 9 This is a schematic diagram of the fitting function;

[0019] Figure 10 This is a flowchart illustrating the fourth embodiment of the method for determining the read voltage in this application;

[0020] Figure 11 This is a schematic diagram of the bit transition unit distribution during SLC readout;

[0021] Figure 12 This is a flowchart illustrating an embodiment of the data reading method of this application;

[0022] Figure 13 This is a schematic diagram of the structure of an embodiment of the electronic device of this application;

[0023] Figure 14 This is a schematic diagram of the structure of an embodiment of the computer-readable storage medium of this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0025] The terms "first," "second," etc., used in this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] In the storage field, when reading data, the host first sends a read request. Taking NAND flash memory as an example, when processing the host's read request, data is read from the NAND flash and decoded using error correction codes, such as LDPC decoding. If decoding fails, a reread process is usually initiated. The read voltage is adjusted according to a reread table, and the NAND flash is read again for re-decoding until successful. If decoding still fails after reaching the maximum number of rereads, a soft read-soft decode process is then performed. This involves multiple soft reads to obtain soft information, followed by soft decoding. If soft decoding fails, more reads can be performed before soft decoding. Before soft decoding, the optimal voltage can be calculated based on the multiple data reads from the NAND flash. Once the optimal voltage is obtained, the soft decoding process can be repeated based on this optimal voltage.

[0028] In storage devices, such as NAND flash memory, there are many different types of noise, such as erase / write cycles, retention time, read interference, and inter-cell interference. These factors all generate noise, causing variations in the number of electrons held in a flash cell, which in turn leads to changes in the optimal read voltage. When the read voltage deviates from the optimal read voltage, it can cause many data bit errors, thereby increasing the probability of decoder failure. Therefore, finding the optimal voltage is crucial for system reliability.

[0029] To find the optimal read voltage, different offset voltages need to be applied for multiple reads. The number of bit transition units distributed in different voltage ranges is obtained based on the data obtained from the multiple reads.

[0030] like Figure 1 , 2 As shown in Figure 3, Figure 1 , 2 Figure 3 shows a schematic diagram of the bit transition unit distribution during SLC readout. Taking SLC as an example, it contains 2 levels. In the figure, the horizontal axis represents voltage, and the vertical axis represents the number of bit transition units.

[0031] Figure 1 , 2 Types 3 and 4 represent common distribution patterns in practice. Specifically, the column height distribution lies between the peaks, valleys, and peak-valleys in the bit jump distribution statistics. Typically, optimal voltage finding algorithms use a quadratic function to fit the column height distribution to determine the valley's location, thus providing the optimal read voltage. However, except for… Figure 3 Besides those applicable to this algorithm, Figure 1 and Figure 2 It may be impossible to accurately calculate the position at the bottom, thus making it impossible to calculate the optimal reading voltage.

[0032] To calculate the optimal read voltage, this application proposes a method provided by the following embodiments.

[0033] Reference Figure 4 , Figure 4 This is a flowchart illustrating a first embodiment of the method for determining the voltage read in this application. It includes, but is not limited to, the following steps.

[0034] S11: Obtain distribution statistics, which include bit transition values ​​corresponding to several different voltage ranges.

[0035] When obtaining the distribution statistics of bit transition values, the voltage range used to obtain the bit transition values ​​includes both a single voltage value and a voltage range consisting of multiple voltage values. That is, the obtained distribution statistics can be the bit transition value A1 corresponding to the first voltage value A, the bit transition value B1 corresponding to the second voltage value B, etc., or the bit transition value C1 corresponding to the first voltage range C, the bit transition value D1 corresponding to the second voltage range D, etc.

[0036] S12: Obtain a preset piecewise quadratic function containing undetermined parameters. The piecewise quadratic function includes a first function and a second function, which are centrally symmetric and continuous.

[0037] Both the first and second functions are quadratic functions, continuous on the x-axis, and centrally symmetric. The undetermined parameters include the coefficients of the quadratic terms of the quadratic functions.

[0038] S13: Use a piecewise quadratic function to fit the distribution statistics and determine the undetermined parameters in the piecewise quadratic function.

[0039] During fitting, when obtaining distribution statistics, a single voltage value is used to obtain bit transition values, and this voltage value is also used to perform function fitting with the corresponding bit transition values.

[0040] During fitting, when obtaining distribution statistics, voltage intervals consisting of multiple voltage values ​​are used. A single voltage value corresponding to that voltage interval is then used to perform function fitting with the corresponding bit transition value. In this embodiment, when using voltage intervals to obtain distribution statistics, the voltage value at the exact center of the voltage interval is selected for subsequent function fitting.

[0041] S14: Substitute the determined parameters into the first function to obtain the first voltage where the axis of symmetry of the first function is located, and substitute the determined parameters into the second function to obtain the second voltage where the second axis of symmetry is located.

[0042] S15: Determine the first voltage or the second voltage as the reading voltage based on the quadratic term coefficient in the undetermined parameters.

[0043] In this embodiment, after obtaining the distribution statistics of bit transition values ​​covering several different voltage ranges, a piecewise quadratic function containing undetermined parameters is used to fit the data. Since the first and second functions included in this piecewise quadratic function are centrally symmetric and continuous, the fitting process yields two axes of symmetry corresponding to the first and second functions. One axis corresponds to the maximum value of one quadratic function, and the other to the minimum value. Therefore, among the voltages corresponding to the two axes of symmetry of the first and second functions, there must be a voltage at which the minimum value of the quadratic function is located. This voltage at the minimum value of the quadratic function is the voltage at which the trough of the distribution statistics is located, and is the optimal reading voltage. Accurately calculating the optimal reading voltage and reading based on this voltage provides the lowest data error rate, improving data reliability. Furthermore, quickly and accurately determining the optimal reading voltage reduces the number of rereads and lowers reading latency.

[0044] This implementation can simultaneously fit all cases, including those where column height information lies at peaks, valleys, and between peaks and valleys, successfully obtaining the optimal read voltage for all situations. This improves the success rate of decoding, reduces read latency, and enhances data reliability. Furthermore, reducing reread processes effectively extends the lifespan of the storage device.

[0045] In one embodiment, the distribution statistics include several different voltage ranges that are consecutive voltage ranges. The intervals between these voltage ranges are equal.

[0046] Obtaining bit transition values ​​based on continuous voltage intervals with equal internal spacing allows for more accurate function fitting, resulting in a function that more closely approximates the actual bit transition distribution.

[0047] Reference Figure 5 , Figure 5 This is a flowchart illustrating a second embodiment of the method for determining the read voltage according to this application. This method is a further extension of step S15 and includes, but is not limited to, the following steps.

[0048] S21: Determine the first or second function with a quadratic coefficient greater than zero as the objective function.

[0049] S22: Determine the voltage at which the axis of symmetry of the objective function lies as the reading voltage.

[0050] The optimal reading voltage is the voltage at the trough. In a piecewise quadratic function with a fitted and determined parameter set, the minimum value of the quadratic function with a coefficient greater than zero corresponds to the trough in the bit jump distribution statistics. Therefore, the voltage at the minimum value, i.e., the voltage at the axis of symmetry of the function, is the optimal reading voltage, and this is determined as the required reading voltage.

[0051] In one embodiment, the expression for the piecewise quadratic function is as follows:

[0052]

[0053] in, For the first function, Let be the second function, -a and a be the coefficients of the quadratic term, d be the distance between the axes of symmetry of the first and second functions, x0 be the offset of the piecewise quadratic function on the x-axis relative to x=0, and y0 be the offset of the piecewise quadratic function on the y-axis relative to y=0.

[0054] Among them, -a, a, d, x0, and y0 are all parameters to be determined.

[0055] The fitted image is as follows Figure 6 As shown, Figure 6 This is a schematic diagram of the fitting function.

[0056] Reference Figure 7 , Figure 7 This is a flowchart illustrating a third embodiment of the method for determining the read voltage according to this application. This method is a further extension of step S15 and includes, but is not limited to, the following steps.

[0057] S31: Determine the center voltage based on several different voltage ranges.

[0058] Determine the target voltage range consisting of all the aforementioned different voltage ranges, and obtain the center voltage of the target voltage range. For example, if the voltage ranges in the distribution statistics are [A,B], [B,C], [C,D], then the target voltage range is [A,D], and the center voltage E = (DA) / 2.

[0059] S32: Determine the first or second voltage corresponding to the absolute value of the smaller difference as the reliable voltage.

[0060] S33: Determine the first voltage or the second voltage as the read voltage based on the quadratic term coefficients in the undetermined parameters and the reliable voltage.

[0061] Typically, after function fitting, due to the good fitting effect, the two axes of symmetry of its quadratic function can accurately correspond to the peak and trough positions of the bit jump distribution statistics. For example... Figure 8 As shown, Figure 8 This is a schematic diagram of the fitting function.

[0062] However, sometimes the fitting results can be affected by noise, which may introduce fitting errors and cause the axis of symmetry to deviate from its original position. For example... Figure 9 As shown, Figure 9 This is a schematic diagram of the fitting function.

[0063] Therefore, in this embodiment, the axis of symmetry closer to the center of the voltage interval with the distribution statistics is further determined to be the more accurate axis of symmetry, and its corresponding axis of symmetry voltage is the more accurate voltage. During a fitting process, the voltage types of the first voltage and / or the second voltage closer to the center of the target voltage interval are determined as reliable voltages, thus identifying them as more accurate voltage data. Based on the determination of reliable voltages, the reading voltage is further determined according to the quadratic term coefficients in the parameters to be determined.

[0064] Determining the first voltage or the second voltage as the read voltage based on the quadratic coefficient in the undetermined parameters and the reliable voltage includes: determining the first voltage or the second voltage whose quadratic coefficient in the corresponding undetermined parameters is greater than zero and is determined to be the reliable voltage as the read voltage; or processing the first voltage or the second voltage whose quadratic coefficient in the corresponding undetermined parameters is less than zero and is determined to be the reliable voltage using a preset voltage, wherein the preset voltage is a preset peak-to-valley spacing voltage or half of a preset peak-to-peak spacing voltage. The processing operations include addition or subtraction.

[0065] Specifically, in one embodiment, if the first voltage is a reliable voltage and the quadratic function corresponding to the first voltage is an objective function with a quadratic coefficient greater than zero, then the first voltage is determined as the read voltage. If the first voltage is not a reliable voltage, but the quadratic function corresponding to the first voltage is an objective function with a quadratic coefficient greater than zero, then the first voltage is not determined as the read voltage. If the first voltage is a reliable voltage, but the quadratic coefficient of the quadratic function corresponding to the first voltage is less than zero, then the first voltage is not determined as the read voltage. If the first voltage is not a reliable voltage, and the quadratic coefficient of the quadratic function corresponding to the first voltage is less than zero, then the first voltage is not determined as the read voltage.

[0066] In one embodiment, if the first voltage or the second voltage is a reliable voltage, but the coefficient of the quadratic term of its corresponding quadratic function is less than zero, then although the first voltage or the second voltage cannot be determined as the read voltage, the read voltage can be calculated based on the first voltage or the second voltage.

[0067] For a first voltage or a second voltage that is determined to be a reliable voltage, but whose corresponding quadratic function has a quadratic term coefficient less than zero, the reading voltage is calculated based on the first voltage or the second voltage, including: obtaining the reading voltage by adding or subtracting a preset voltage from the first voltage, or obtaining the reading voltage by adding or subtracting a preset voltage from the second voltage. The preset voltage is a preset peak-to-valley spacing voltage or half of a preset peak-to-peak spacing voltage.

[0068] The preset peak-valley spacing voltage and preset peak-to-peak spacing voltage can be determined based on statistical principles and prior statistical data. Multiple sets of pre-collected peak-valley data for reading voltage are obtained, resulting in multiple sets of peak-valley spacing voltage and multiple sets of peak-to-peak spacing voltage. The average value is then taken as the preset peak-valley spacing voltage or preset peak-to-peak spacing voltage. This average value is used for subsequent reading voltage calculations.

[0069] Reference Figure 10 , Figure 10 This is a flowchart illustrating the fourth embodiment of the method for determining the read voltage according to this application. This method is a further extension of step S15 and includes, but is not limited to, the following steps.

[0070] S41: Determine the target voltage range consisting of several different voltage ranges.

[0071] S42: Determine the first voltage and / or the second voltage located within the target voltage range as the reliable voltage.

[0072] S43: Determine the first voltage or the second voltage as the read voltage based on the quadratic term coefficients in the undetermined parameters and the reliable voltage.

[0073] Similar to the above embodiments, since the fitting results are affected by noise and thus produce fitting errors, in this embodiment, the axis of symmetry located within the voltage range of the distribution statistics is determined to be the accurate axis of symmetry, and its corresponding voltage is the accurate voltage. During a single fitting process, the voltage types of the first and / or second voltages located within the target voltage range are determined as reliable voltages, thus confirming them as accurate voltage data. Based on the determination of reliable voltages, the reading voltage is further determined according to the quadratic term coefficients in the parameters to be determined.

[0074] In the above embodiments, if the absolute value of the difference is determined and the absolute value of the difference between the first voltage and the second voltage is equal, it can be further determined whether they are within the target voltage range. If both the first voltage and the second voltage are within the target voltage range, then both are reliable voltages. If both the first voltage and the second voltage are outside the target voltage range, then neither is a reliable voltage.

[0075] In one embodiment, it can be further determined whether the first voltage and the second voltage interval are located within the target voltage interval. If one of the first and second voltages is located within the target voltage interval and the other is located outside the target voltage interval, then the voltage located within the target voltage interval is determined to be a reliable voltage, and the voltage located outside the target voltage interval is not a reliable voltage. If both the first and second voltages are located within or outside the target voltage interval, further determination can be made based on the absolute value of the difference between the first voltage, the second voltage, and the center voltage of the target voltage interval. The voltage with the smaller absolute value of the difference is determined to be a reliable voltage. The same or similar steps can be referred to in the above embodiments, and will not be repeated here.

[0076] In one embodiment, before fitting the distribution statistics using a piecewise quadratic function, the method includes: preprocessing the distribution statistics.

[0077] Preprocessing includes smoothing.

[0078] In one embodiment, the preprocessing includes: calculating the second derivative of the bit transition value corresponding to each voltage interval based on distribution statistics; deleting bit transition values ​​whose second derivative is less than a preset threshold; and performing function fitting based on the remaining bit transition values ​​and the corresponding voltage intervals to obtain the read voltage.

[0079] Reference Figure 11 This is a schematic diagram of the bit transition unit distribution during SLC readout.

[0080] In some cases, due to factors such as data retention time and erase / write cycles, the height of the resulting bit transition distribution bars may shift closer to nearby peaks. The height of these nearby peaks affects the function fitting results, causing the fitted function to have a larger opening, thus making the calculated optimal read voltage deviate from the actual optimal read voltage. Therefore, to obtain an accurate optimal read voltage, it is necessary to filter out these bit transition values ​​that are close to the peaks.

[0081] from Figure 11As can be seen, starting from the lowest bit transition value, its corresponding first derivative continuously decreases along the negative X-axis (the direction of decreasing voltage) and continuously increases along the positive X-axis (the direction of increasing voltage). Starting from the lowest bit transition value, along the negative X-axis, in voltage range E, its first derivative continuously decreases. Along the positive X-axis, in voltage range F, its first derivative continuously increases. The voltage at the boundary between E and F corresponds to the trough voltage. However, starting from the voltage at the boundary between voltage ranges D and E, along the negative X-axis, in voltage range D (the voltage at the left endpoint of voltage range D corresponds to the peak voltage), its first derivative begins to continuously increase. Starting from the voltage at the boundary between voltage ranges F and G, along the positive X-axis, in voltage range G (the voltage at the right endpoint of voltage range G corresponds to the peak voltage), its first derivative begins to continuously decrease. Then it can be considered that starting from the lowest bit transition value, along any direction of the X-axis, when the trend of its first derivative begins to change, the voltage range corresponding to the bit transition value is considered to be less than the distance to the voltage corresponding to the peak than the distance to the voltage corresponding to the trough. That is, compared to the trough, the column height of the bit transition value begins to be closer to the peak.

[0082] In this voltage range from D to G, the first derivative changes along the positive X-axis as follows: In the D range, the first derivative is less than zero and continuously decreases, but the decreasing trend gradually weakens; in the E range, the first derivative is less than zero but continuously increases, and the increasing trend gradually strengthens; in the F range, the first derivative is greater than zero and continuously increases, but the increasing trend gradually weakens; in the G range, the first derivative is greater than zero but continuously decreases, and the decreasing trend gradually strengthens.

[0083] Therefore, it can be considered that within this voltage range, the second derivative changes along the positive X-axis as follows: from interval D to interval E, the second derivative continuously increases; from interval F to interval G, the second derivative continuously decreases.

[0084] Therefore, it can be considered that when the second derivative is large, the voltage range corresponding to the bit transition value is closer to the trough voltage, and the height of the bit transition value is closer to the trough than the peak. When the second derivative is small, the voltage range corresponding to the bit transition value is closer to the peak voltage, and the height of the bit transition value is closer to the peak than the trough.

[0085] By filtering using the second derivative, bit transition values ​​in the voltage range closer to the peak are removed, while bit transition values ​​in the voltage range closer to the trough are retained. Subsequent function fitting is performed based on these bit transition values, thus avoiding a situation where the calculated optimal reading voltage deviates from the actual optimal reading voltage due to the use of bit transition values ​​closer to the peak.

[0086] Reference Figure 11 , Figure 11This is a schematic flowchart of an embodiment of the data reading method of this application. It includes, but is not limited to, the following steps.

[0087] S51: Get the read data.

[0088] S52: In response to the failure of decoding the read data, execute the read voltage determination method to determine the read voltage.

[0089] The reading voltage determination method is any embodiment of the above-described reading voltage determination method and possible combinations thereof.

[0090] S53: Reread the data based on the read voltage and decode it to obtain the read result.

[0091] After determining the reading voltage using the above method, reading based on this reading voltage can provide the lowest data error rate, improve data reliability, and reduce the number of rereads, thus reducing reading latency.

[0092] like Figure 12 As shown, Figure 12 This is a schematic diagram of the structure of an embodiment of the electronic device of this application.

[0093] The electronic device includes a processor 110 and a memory 120.

[0094] Processor 110 controls the operation of electronic devices. Processor 110 may also be referred to as a CPU (Central Processing Unit). Processor 110 may be an integrated circuit chip with signal sequence processing capabilities. Processor 110 may also be a general-purpose processor, a digital signal sequence processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. A general-purpose processor may be a microprocessor or any conventional processor.

[0095] The memory 120 stores the instructions and program data required for the processor 110 to operate.

[0096] The processor 110 is used to execute instructions to implement the methods provided in any embodiment and possible combination of the aforementioned read voltage determination method and data read method of this application.

[0097] like Figure 13 As shown, Figure 13 This is a schematic diagram of the structure of an embodiment of the computer-readable storage medium of this application.

[0098] One embodiment of the computer-readable storage medium of this application includes a memory 210 that stores program data that, when executed, implements the methods provided in any embodiment and possible combination of the voltage determination method and data reading method of this application.

[0099] The memory 210 may include a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, or other media that can store program instructions. Alternatively, it may be a server that stores the program instructions, which can send the stored program instructions to other devices for execution or execute the stored program instructions itself.

[0100] In summary, after obtaining the distribution statistics of bit transition values ​​across several different voltage ranges, a piecewise quadratic function containing undetermined parameters is used to fit the data. Since the first and second functions included in this piecewise quadratic function are centrally symmetric and continuous, the fitting process yields two axes of symmetry corresponding to the first and second functions. One axis corresponds to the maximum value of one quadratic function, and the other to the minimum value. Therefore, among the voltages corresponding to the two axes of symmetry of the first and second functions, there must exist a voltage that corresponds to the minimum value of the quadratic function. This voltage, representing the minimum value of the quadratic function, is the trough voltage of the distribution statistics and represents the optimal reading voltage. Accurately calculating the optimal reading voltage and reading based on this voltage provides the lowest data error rate, improves data reliability, reduces the number of rereads, and lowers reading latency.

[0101] In the several embodiments provided in this application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0102] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0103] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0104] If the integrated units in the other embodiments described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0105] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for determining a read voltage, characterized in that, The method includes: Obtain distribution statistics, which include bit transition values ​​corresponding to several different voltage ranges; Obtain a preset piecewise quadratic function containing undetermined parameters. The piecewise quadratic function includes a first function and a second function. The first function and the second function are centrally symmetric and continuous. The undetermined parameters include the coefficients of the quadratic terms of the first function and the second function. The piecewise quadratic function is used to fit the distribution statistics to determine the undetermined parameters in the piecewise quadratic function; Substituting the determined undetermined parameters into the first function yields the first voltage at the axis of symmetry of the first function, and substituting the determined undetermined parameters into the second function yields the second voltage at the axis of symmetry of the second function. The first voltage or the second voltage is determined as the read voltage based on the quadratic term coefficient in the undetermined parameters.

2. The method of claim 1, wherein, The several different voltage ranges in the distribution statistics are continuous voltage ranges, and the intervals between the voltage ranges are equal.

3. The method of claim 1, wherein, The step of determining the first voltage or the second voltage as the read voltage based on the quadratic term coefficient in the undetermined parameter includes: The first or second function with a quadratic coefficient greater than zero is identified as the objective function; The voltage at which the axis of symmetry of the objective function lies is determined as the reading voltage.

4. The method of claim 1, wherein, The step of determining the first voltage or the second voltage as the read voltage based on the quadratic term coefficient in the undetermined parameter includes: The center voltage is determined based on the aforementioned different voltage ranges; Obtain the absolute value of the difference between the first voltage and the center voltage, and the absolute value of the difference between the second voltage and the center voltage; The first voltage or the second voltage corresponding to the smaller absolute value of the difference is determined as the reliable voltage; The first voltage or the second voltage is determined as the read voltage based on the quadratic term coefficient in the undetermined parameters and the reliable voltage.

5. The method according to claim 1, characterized in that, The step of determining the first voltage or the second voltage as the read voltage based on the quadratic term coefficient in the undetermined parameter includes: The target voltage range is determined by comprising the aforementioned different voltage ranges; The first voltage and / or the second voltage located within the target voltage range are determined as reliable voltages; The first voltage or the second voltage is determined based on the quadratic term coefficient in the undetermined parameters and the reliable voltage.

6. The method according to claim 4 or 5, characterized in that, The step of determining the first voltage or the second voltage as the read voltage based on the quadratic term coefficient in the undetermined parameter and the reliable voltage includes: The first voltage or the second voltage, whose quadratic term coefficient is greater than zero in the corresponding undetermined parameters and is determined to be the reliable voltage, is determined as the read voltage; or The reading voltage is obtained by processing the first voltage or the second voltage, which is determined to be the reliable voltage and whose quadratic term coefficient is less than zero in the corresponding undetermined parameter, using a preset voltage. The preset voltage is half of the preset peak-valley spacing voltage or the preset peak-peak spacing voltage.

7. The method according to claim 1, characterized in that, Before fitting the distribution statistics using the piecewise quadratic function, the following steps are included: The distribution statistics are preprocessed.

8. A data reading method, characterized in that, The method includes: Get and read data; In response to a failure to decode the read data, the read voltage determination method as described in any one of claims 1-7 is executed to determine the read voltage; Based on the read voltage, the data is read again and decoded to obtain the read result.

9. An electronic device, characterized in that, It includes a memory and a processor, the memory being used to store program data, the program data being executable by the processor to implement the method as described in any one of claims 1-8.

10. A computer-readable storage medium, characterized in that, It stores program data and can be executed by a processor to implement the method as described in any one of claims 1-8.

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