Refresh circuit, refresh method, memory, and storage system

Abstract

The application provides a refresh circuit, a refresh method, a memory and a storage system. The refresh circuit comprises: a counting unit configured to count an external pulse signal received and reset a counting value in response to a row hammer refresh command; a random unit configured to generate a first random number before the counting unit outputs the counting value; and a first generation unit connected to the counting unit and the random unit, configured to obtain the counting value generated by the counting unit and a plurality of first random numbers generated by the plurality of random units, wherein the first random numbers generated by different random units are different; the first generation unit is further configured to output a sampling pulse when the counting value is equal to any first random number; a second generation unit connected to the first generation unit, configured to obtain a corresponding access address when the sampling pulse is received, and generate a row hammer address based on at least one obtained access address; and a refresh unit configured to refresh at least one row address adjacent to the row hammer address in response to a next row hammer refresh command.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and to, but is not limited to, a refresh circuit, a refresh method, a memory, and a memory system. Background Technology

[0002] With the continuous development of science and technology, the density of semiconductor memory devices is constantly increasing. High data reliability, high access speed, and smaller chip size have become important trends in the development of semiconductor memory. However, the electromagnetic interactions between memory cells are having an increasing impact on the memory cells, thus increasing the possibility of data loss.

[0003] Dynamic Random Access Memory (DRAM) is a type of volatile memory that stores information using the charge accumulated in the capacitors of its memory cells as a physical signal. The charge in these cells decays over time, necessitating periodic refresh operations to prevent data loss. Before data is lost due to charge leakage, the charge stored in the memory cells can be maintained by recharging. This recharging is called a refresh operation, and it can be repeated until significant charge loss occurs to replenish the charge and prevent data errors. However, when the word line corresponding to a single address in a memory cell is frequently turned on, it can cause excessive charge leakage from the capacitors of adjacent addresses before a refresh operation, leading to data errors and data loss. Summary of the Invention

[0004] In view of this, embodiments of this application provide a refresh circuit, a refresh method, a memory, and a storage system.

[0005] In a first aspect, embodiments of this application provide a refresh circuit, comprising: a counting unit for counting received external pulse signals and resetting the count value in response to a row hammer refresh command; a random unit for generating a first random number before the counting unit outputs the count value; a first generation unit connected to the counting unit and a plurality of the random units for acquiring the count value generated by the counting unit and a plurality of the first random numbers generated by the random units, wherein the first random numbers generated by different random units are different; the first generation unit is further configured to output a sampling pulse when the count value is equal to any of the first random numbers; a second generation unit connected to the output terminal of the first generation unit for acquiring a corresponding access address when the sampling pulse is received, and generating a row hammer address based on at least one of the acquired access addresses; and a refresh unit for refreshing at least one row address adjacent to the row hammer address in response to the next row hammer refresh command.

[0006] In some embodiments, the random unit is further configured to adjust the maximum random value of the first random number based on the ambient temperature.

[0007] In some embodiments, the random unit includes n pseudo-random number units, each of which is used to generate a second random number in response to the row hammer refresh command; the random unit is used to output the sum of the m generated second random numbers based on the ambient temperature as the first random number; wherein, n≥m≥1; or, the random unit is used to output a second random number based on the ambient temperature as the first random number.

[0008] In some embodiments, the refresh circuit further includes: a temperature detection module for detecting the ambient temperature; a temperature flag module for outputting different temperature flag signals based on the ambient temperature, wherein different temperature flag signals are used to characterize that the refresh circuit is at different ambient temperatures; and the random unit is further used to receive the temperature flag signals and to adjust the maximum random value of the first random number based on the temperature flag signals.

[0009] In some embodiments, the counting unit has a maximum count value, and the counting unit is further configured to adjust the maximum count value based on the ambient temperature.

[0010] In some embodiments, the ambient temperature includes a first temperature range and a second temperature range, and the counting unit includes a first counting unit and a second counting unit. The maximum count value of the first counting unit is different from the maximum count value of the second counting unit. The first counting unit is enabled based on the ambient temperature in the first temperature range, and the second counting unit is enabled based on the ambient temperature in the second temperature range. The first counting unit and the second counting unit select one pair to count the external pulse signal to generate the count value.

[0011] In some embodiments, the period of the external pulse signal is 2 k The product of -1 is less than the minimum period of the row hammer refresh; k is the number of binary bits of the random unit.

[0012] In some embodiments, the number of random units is greater than or equal to 3; the second generation unit is specifically used to generate the row hammer address based on one or more access addresses that appear most frequently among the acquired access addresses.

[0013] In some embodiments, the first generation unit includes: a presampling unit for outputting a presampling pulse, the period of which is consistent with the period of the external pulse signal; a sampling signal generation unit for outputting a sampling signal when the count value is equal to any of the first random numbers; and a sampling pulse generation unit connected to the presampling unit and the sampling signal generation unit for performing an AND operation on the presampling pulse and the sampling signal to output the sampling pulse.

[0014] Secondly, embodiments of this application provide a refresh method, comprising: counting received external pulse signals and resetting the count value in response to a row hammer refresh command; generating and outputting a plurality of different first random numbers before outputting the count value; acquiring the count value and the plurality of first random numbers; outputting a sampling pulse when the count value is equal to any of the first random numbers; acquiring a corresponding access address when the sampling pulse is received, and generating a row hammer address based on at least one of the acquired access addresses; and refreshing at least one row address adjacent to the row hammer address in response to a next row hammer refresh command.

[0015] In some embodiments, generating a first random number before outputting the count value further includes: adjusting the maximum random value of the first random number based on the ambient temperature.

[0016] In some embodiments, adjusting the maximum random value of the first random number based on ambient temperature includes: generating n second random numbers in response to the row hammer refresh command; outputting the sum of the m generated second random numbers based on ambient temperature as the first random number; wherein n≥m≥1; or, outputting one second random number based on ambient temperature as the first random number.

[0017] In some embodiments, the refresh method further includes: detecting the ambient temperature; outputting different temperature flag signals based on the ambient temperature, wherein different temperature flag signals are used to characterize different ambient temperatures; adjusting the maximum random value of the first random number based on the ambient temperature includes: adjusting the maximum random value of the first random number based on the temperature flag signals.

[0018] In some embodiments, the refresh method further includes: adjusting the maximum count value of the count based on the ambient temperature.

[0019] In some embodiments, the ambient temperature includes a first temperature range and a second temperature range; counting the received external pulse signals includes: counting the external pulse signals based on the ambient temperature in the first temperature range to generate a first count value; counting the external pulse signals based on the ambient temperature in the second temperature range to generate a second count value; one of the first count value and the second count value is selected as the count value, and the maximum count values ​​of the first count value and the second count value are different.

[0020] In some embodiments, the period of the external pulse signal is 2 k The product of -1 is less than the minimum period of the row hammer refresh; k is the number of binary bits of the first random number.

[0021] In some embodiments, the number of the first random numbers is greater than or equal to 3; generating the row hammer address based on at least one of the obtained access addresses includes: generating the row hammer address based on one or more access addresses that appear most frequently among the obtained access addresses.

[0022] Thirdly, embodiments of this application provide a memory, including: a memory cell array; and peripheral circuitry coupled to the memory cell array; the peripheral circuitry including any of the refresh circuits described in the above embodiments.

[0023] Fourthly, embodiments of this application provide a storage system, including: a memory, including any of the refresh circuits described in the above embodiments; a controller coupled to the memory; the controller being used to control the memory.

[0024] In the refresh circuit provided in this application embodiment, a counting unit is used to count external pulses to generate a count value, and multiple random units are used to generate multiple different first random numbers. The first generation unit outputs a sampling pulse when the count value is equal to any of the first random numbers, and the second generation unit obtains the access address based on the sampling pulse to generate the row hammer address. In this way, by generating multiple different first random numbers, at least one access address can be randomly captured within the row hammer refresh cycle, increasing the randomness and uniformity of the captured address, thereby improving the accuracy of the generated row hammer address and reducing data errors and data loss caused by the row hammer effect. Attached Figure Description

[0025] Figure 1 A schematic diagram of a refresh circuit provided in an embodiment of this application;

[0026] Figure 2 A schematic diagram of another refresh circuit provided in an embodiment of this application;

[0027] Figure 3A flowchart illustrating the steps of a refresh method provided in this application embodiment;

[0028] Figure 4 A schematic diagram of yet another refresh circuit provided in an embodiment of this application;

[0029] Figure 5 A timing diagram of a refresh circuit provided in an embodiment of this application;

[0030] Figure 6 A schematic diagram of a memory provided for an embodiment of this application;

[0031] Figure 7 This is a schematic diagram of a storage system provided in an embodiment of this application. Detailed Implementation

[0032] To facilitate understanding of this application, exemplary embodiments disclosed herein will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of the disclosure of this application to those skilled in the art.

[0033] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In some embodiments, to avoid confusion with this application, some technical features well-known in the art are not described; that is, not all features of the actual embodiments may be described herein, nor well-known functions and structures may be described in detail.

[0034] Generally, terms can be understood at least in part from their use in context. For example, depending at least in part on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in a singular sense, or it can be used to describe a combination of features, structures, or characteristics in a plural sense. Similarly, terms such as "a" or "described" can also be understood to convey either a singular or a plural usage, depending at least in part on the context. Additionally, the use of "based on" can be understood to not necessarily convey an exclusive set of factors, and can alternatively allow for the presence of additional factors that are not necessarily explicitly described, also depending at least in part on the context.

[0035] Unless otherwise defined, the terminology used herein is intended only to describe particular embodiments and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0036] To fully understand this application, detailed steps and structures will be presented in the following description to illustrate the technical solution of this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0037] In some embodiments, regular memory refresh includes activation (Act) and precharge (Pre) operations. When a word address line in the memory undergoes tens of thousands of activation and precharge operations consecutively, the leakage rate of capacitors on physically adjacent address lines may exceed the natural leakage rate. This causes capacitors at adjacent addresses to lose too much charge before the regular refresh signal arrives, resulting in data loss and erroneous storage. This phenomenon is generally called the row hammer effect. The row that is repeatedly accessed is called the aggressor row, and the address of the aggressor row is the row hammer address. The rows adjacent to the aggressor row are called the victim rows. Row hammer refresh involves refreshing the victim rows after the memory has been operating for a period of time to replenish their charge and ensure data integrity. The address of the victim row is the row hammer refresh address.

[0038] In some embodiments, multiple activation operations occur between two row hammer refreshes, and the access address of the activation operation at a fixed time is selected as the row hammer address. However, the row hammer address selected in this way is prone to missing the real intruding row, resulting in low accuracy. Therefore, for the selection of the row hammer address, it is desirable to capture access addresses as randomly as possible between two row hammer refreshes, and to find the address line with the highest access frequency by comparing the frequency of occurrence of the captured access addresses.

[0039] In some embodiments, the frequency of the hammer refresh changes with ambient temperature. Higher ambient temperatures result in a higher refresh frequency, meaning shorter intervals between refreshes; conversely, lower ambient temperatures result in a lower refresh frequency, meaning longer intervals between refreshes. Therefore, for any ambient temperature and any hammer refresh interval, the probability of an access address being captured within different intervals needs to be approximately equal. That is, when the hammer refresh interval is longer, more access addresses are captured; when the hammer refresh interval is shorter, fewer access addresses are captured.

[0040] like Figure 1 As shown, this application embodiment provides a refresh circuit 100, including: a counting unit 101, used to count received external pulse signals 10a and reset the count value 11a in response to a row hammer refresh command RHR; a random unit 102, used to generate a first random number 12a before the counting unit 101 outputs the count value 11a; and a first generation unit 103, connected to the counting unit 101 and the plurality of random units 102, used to obtain the count value 11a generated by the counting unit 101 and the plurality of the first random numbers 12a generated by the plurality of random units 102, and to generate different numbers. The first random number 12a generated by the random unit 102 is different; the first generation unit 103 is also used to output a sampling pulse 13a when the count value 11a is equal to any of the first random numbers 12a; the second generation unit 104 is connected to the output terminal of the first generation unit 103, and is used to obtain the corresponding access address 15a when the sampling pulse 13a is received, and to generate a row hammer address 14a based on at least one of the obtained access addresses; the refresh unit 105 is used to refresh at least one row address adjacent to the row hammer address 14a in response to the next row hammer refresh command RHR.

[0041] In this embodiment, the counting unit 101 counts the number of pulses of the received external pulse signal 10a to generate a count value 11a, and the counting unit 101 resets the count value 11a in response to the hammer refresh command RHR. Exemplarily, the external pulse signal 10a can be provided by a ring oscillator, where the external pulse signal 10a can be a square wave pulse signal. The counting unit 101 is connected to the ring oscillator and counts the number of pulses of the square wave pulse signal, thereby generating and outputting the count value 11a. In some embodiments, after receiving the hammer refresh command RHR, the count value 11a generated and output by the counting unit 101 changes continuously as the number of pulses of the received external pulse signal 10a increases; when the counting unit 101 receives the next hammer refresh command RHR, the counting unit 101 resets, thereby resetting the count value 11a.

[0042] In this embodiment, the random unit 102 is used to generate a first random number 12a in response to the row hammer refresh command RHR before the counting unit 101 outputs the count value 11a. The refresh circuit 100 provided in this application may include multiple random units 102, and the multiple random units 102 generate multiple first random numbers 12a according to the received row hammer refresh command RHR. Exemplarily, the random unit 102 may include a linear feedback shift register (LFSR), which can generate pseudo-random numbers according to the received input signal, where the input signal can be the row hammer refresh command RHR, and the pseudo-random number is the first random number 12a. In some embodiments, after receiving the row hammer refresh command RHR, the random unit 102 generates and outputs a first random number 12a. When the random unit 102 receives the next row hammer refresh command RHR, the random unit 102 updates and outputs the first random number 12a. That is, between two row hammer refresh commands RHR, i.e., in one row hammer refresh cycle, the first random number 12a generated by the random unit 102 can remain unchanged, or it can only generate the first random number 12a once.

[0043] In this embodiment, the first generation unit 103 is connected to the counting unit 101 and multiple random units 102, and is used to obtain a count value 11a and multiple first random numbers 12a. The first random numbers 12a generated by different random units 102 at the same time are different, meaning that the first random numbers 12a generated by different random units 102 based on the same row refresh command RHR are different. The first generation unit 103 is also used to compare the count value 11a and the multiple first random numbers 12a, and output a sampling pulse 13a when the count value 11a is equal to any one of the first random numbers 12a. For example, one random unit 102 includes an LFSR. The pseudo-random number generated by the LFSR can be directly used as the first random number 12a. By setting the initial value (Seed) of each LFSR to a different value, the multiple pseudo-random numbers generated by multiple LFSRs at the same time can be different, thereby enabling different random units 102 to generate different first random numbers 12a.

[0044] Optionally, a random unit 102 may include multiple LFSRs, and the multiple pseudo-random numbers generated by the multiple LFSRs in a random unit 102 can be processed to generate different first random numbers 12a by different random units 102. In addition, optionally, if the first generation unit 103 receives two identical first random numbers 12a, the first generation unit 103 can generate an excitation signal to cause the random unit 102 that is repeating the same number to regenerate the first random number 12a, until multiple different first random numbers 12a are obtained, which is the same number as the number of random units 102. In this case, a random unit 102 may generate multiple first random numbers 12a in one row hammer refresh cycle.

[0045] In some embodiments, the first generation unit 103 connects each random unit 102 to the counting unit 101, and compares the count value 11a with each first random number 12a through a circuit including multiple logic gates. When the count value 11a at a certain moment is equal to any first random number 12a, the first generation unit 103 outputs a sampling pulse 13a.

[0046] In this embodiment, the second generation unit 104 is connected to the output of the first generation unit 103, and is used to capture the corresponding access address 15a when a sampling pulse 13a is received, and to generate a row hammer address 14a based on at least one captured access address. For example, in a row hammer refresh cycle, there exists a moment when the count value 11a equals any first random number 12a. At this time, the second generation unit 104 receives the sampling pulse 13a output by the first generation unit 103 and captures the access address 15a. Then, the second generation unit 104 determines the row hammer address 14a based on at least one captured access address 15a in a row hammer refresh cycle. In some embodiments, the second generation unit 104 can use the access address 15a with the highest frequency among the captured access addresses 15a as the row hammer address 14a. In this way, by generating multiple different first random numbers 12a, at least one access address 15a can be randomly captured within the row hammer refresh cycle, increasing the randomness and uniformity of the captured address, thereby improving the accuracy of the generated row hammer address 14a and reducing data errors and data loss caused by the row hammer effect.

[0047] In this embodiment, the refresh unit 105 is connected to the second generation unit 104 and is used to refresh at least one row address adjacent to the row hammer address 14a in response to the next row hammer refresh command RHR. Here, the at least one row address adjacent to the row hammer address 14a is the victim row in the row hammer effect. Optionally, depending on the performance and power consumption requirements of the refresh circuit and memory, one row address adjacent to the row hammer address 14a can be selected for refresh to reduce power consumption; alternatively, multiple, or even all, adjacent row addresses can be selected for refresh to improve the accuracy of refreshing the victim row.

[0048] In some embodiments, the random unit 102 is further configured to adjust the maximum random value of the first random number 12a based on the ambient temperature.

[0049] In this embodiment, the frequency of the row hammer refresh changes with the ambient temperature. The randomization unit 102 can adjust the maximum value of the first random number 12a according to the ambient temperature to ensure that the number of access addresses 15a captured remains constant and maintains uniformity under different temperatures. For example, when the ambient temperature is high, the row hammer refresh cycle is short and the maximum value of the count value 11a is small. At this time, the randomization unit 102 can decrease the maximum value of the first random number 12a, so that the number of times the count value 11a equals any first random number 12a in one row hammer refresh cycle remains unchanged, and the number of access addresses 15a captured by the second generation unit 104 remains constant and maintains uniformity. When the ambient temperature is low, the row hammer refresh cycle is long and the maximum value of the count value 11a is large. At this time, the randomization unit 102 can increase the maximum value of the first random number 12a, so that the number of times the count value 11a equals any first random number 12a in one row hammer refresh cycle remains constant, and the number of access addresses 15a captured by the second generation unit 104 remains constant and maintains uniformity. This ensures that the number of access addresses 15a captured by the refresh circuit 100 remains constant at different temperatures.

[0050] In some embodiments, such as Figure 2 As shown, the random unit 102 includes n pseudo-random number units 1021, each of the pseudo-random number units 1021 being used to generate a second random number in response to the row hammer refresh command RHR; the random unit 102 is used to output the sum of the m generated second random numbers based on the ambient temperature as the first random number 12a; where n≥m≥1; or, the random unit 102 is used to output a second random number based on the ambient temperature as the first random number 12a.

[0051] In this embodiment, the random unit 102 includes n pseudo-random number units 1021, where n is an integer greater than or equal to 1. The pseudo-random number unit 1021 generates a pseudo-random number upon receiving a row hammer refresh command (RHR) to serve as a second random number. Exemplarily, the pseudo-random number unit 1021 can be an LFSR, and a k-bit linear feedback shift register can generate 2... k -1 pseudo-random numbers, where k is a positive integer. The random unit 102 can, based on different ambient temperatures, output the sum of m of the n second random numbers from the given n random numbers, as the first random number 12a, where n ≥ m ≥ 1; or directly output one of the second random numbers as the first random number 12a. It is worth noting that the first generation unit 103 may also include a random number detection unit. This unit detects whether the multiple first random numbers 12a generated by the multiple random units 102 are all different. When a first random number 12a is repeated, the random number detection unit controls the corresponding random unit 102 to regenerate the first random number 12a.

[0052] In some embodiments, when the ambient temperature is high, the random unit 102 directly outputs one of the second random numbers as the first random number 12a, in which case the maximum random value of the first random number 12a is small; when the ambient temperature is low, the random unit 102 outputs the sum of m second random numbers as the first random number 12a, in which case the maximum random value of the first random number 12a is large. Thus, it can be ensured that under different temperatures and within the same time interval, the number of times the count value 11a equals any of the first random numbers 12a remains unchanged, that is, the refresh circuit 100 captures the access address 15a with the same probability, maintaining uniformity.

[0053] In some embodiments, such as Figure 2 As shown, the refresh circuit 100 further includes: a temperature detection module 106 for detecting the ambient temperature; a temperature flag module 1061 for outputting different temperature flag signals 16a based on the ambient temperature, wherein different temperature flag signals 16a are used to characterize that the refresh circuit 100 is at different ambient temperatures; and a random unit 102 for receiving the temperature flag signals 16a and for adjusting the maximum random value of the first random number 12a based on the temperature flag signals 16a.

[0054] In this embodiment, the refresh circuit 100 further includes a temperature detection module 106 and a temperature flag module 1061. The temperature detection module 106 detects the ambient temperature at which the refresh circuit 100 is located. The temperature flag module 1061 is connected to the temperature detection module 106 and outputs different temperature flag signals 16a according to the ambient temperature. The temperature flag signals 16a represent different ambient temperatures at which the refresh circuit 100 is located. The random unit 102 is also connected to the temperature flag module 1061 and adjusts the maximum random value of the first random number 12a according to the received temperature flag signal 16a. For example, when the random unit contains only one pseudo-random number unit, the maximum random value of the single pseudo-random number unit can be adjusted; when the random unit contains multiple pseudo-random number units, the number of second random numbers included in the first random number as the sum can be adjusted, thereby adjusting the maximum random value of the random unit.

[0055] In some embodiments, such as Figure 2 As shown, the counting unit 101 has a maximum count value, and the counting unit 101 is also used to adjust the maximum count value based on the ambient temperature.

[0056] In this embodiment, the counting unit 101 counts the number of pulses of the received external pulse signal 10a to generate a count value 11a. The maximum value of the count value 11a generated by the counting unit 101 is the maximum count value. As can be seen from the above embodiments, when the ambient temperature is high, the hammer refresh cycle is short, and the maximum random value of the first random number 12a is small; conversely, when the ambient temperature is low, the hammer refresh cycle is long, and the maximum random value of the first random number 12a is large. Therefore, the counting unit 101 can be connected to the temperature flag module 1061 to adjust the maximum count value based on the ambient temperature represented by the temperature flag signal 16a, corresponding to the maximum random value of the first random number 12a. In some embodiments, the counting unit 101 can adjust the maximum count value in real time according to the ambient temperature. In some embodiments, when the count value 11a generated by the counting unit 101 reaches the maximum count value, the counting unit 101 can enter a sleep state to save power.

[0057] In some embodiments, such as Figure 2As shown, the ambient temperature includes a first temperature range and a second temperature range. The counting unit 101 includes a first counting unit 1011 and a second counting unit 1012. The maximum count value of the first counting unit 1011 is different from the maximum count value of the second counting unit 1012. The first counting unit 1011 is enabled based on the ambient temperature in the first temperature range, and the second counting unit 1012 is enabled based on the ambient temperature in the second temperature range. The first counting unit 1011 and the second counting unit 1012 select one pair to count the external pulse signal 10a to generate the count value 11a.

[0058] In this embodiment, the counting unit 101 further includes a first counting unit 1011 and a second counting unit 1012. The ambient temperature may include a first temperature range and a second temperature range. The first counting unit 1011 counts the external pulse signal 10a when the ambient temperature is within the first temperature range to generate a count value 11a; the second counting unit 1012 counts the external pulse signal 10a when the ambient temperature is within the second temperature range to generate a count value 11a. The first counting unit 1011 and the second counting unit 1012 count based on different ambient temperatures, and their maximum count values ​​are also different.

[0059] In some embodiments, the ambient temperature represented by the first temperature range is higher than the ambient temperature represented by the second temperature range, and the first counting unit 1011 can be an i-bit counter with a maximum counting value of 2. i -1, where i is the number of binary digits, and the second counting unit 1012 can be an i+1-bit counter with a maximum counting value of 2. i+1 -1. That is, when the ambient temperature is high, the first counting unit 1011 with the smaller maximum count value is used for counting; when the ambient temperature is low, the second counting unit 1012 with the larger maximum count value is used for counting. It can be understood that the ambient temperature can also include two or more temperature ranges, and the counting unit 101 includes the same number of sub-counting units as the number of temperature ranges. Each sub-counting unit counts the external pulse signal 10a when the ambient temperature is within the corresponding temperature range to generate a count value 11a.

[0060] In some embodiments, the period of the external pulse signal 10a is related to 2. k The product of -1 is less than the minimum period of the row hammer refresh; k is the number of binary bits of the random unit 102.

[0061] In this embodiment, the period of the external pulse signal 10a is t, and the minimum time interval between two horizontal hammer refresh commands RHR, i.e., the minimum period of the horizontal hammer refresh, is tRHR. min, and (2 k -1)*t <tRHR min , where k is the number of binary bits in the random unit 102. It can be understood that 2 k -1 is the maximum random value of the first random number 12a generated by the k-bit random unit 102. In some embodiments, the number of binary bits i in the counting unit 101 and the number of binary bits k in the random unit 102 can be the same, in which case (2 k -1)*t is the time it takes for counting unit 101 to count to the maximum random value, therefore the minimum period tRHR for the row hammer refresh is... min It should be greater than (2) k -1)*t, to prevent the count value 11a from being reset before the count reaches the maximum value.

[0062] In some embodiments, the number of random units 102 is greater than or equal to 3; the second generation unit 104 is specifically used to generate the row hammer address 14a based on one or more access addresses 15a that appear most frequently among the acquired access addresses 15a.

[0063] In this embodiment, the number of random units 102 is greater than or equal to 3. Therefore, in one row hammer refresh cycle, there may be three instances where the first random number 12a is equal to the count value 11a, meaning the second generation unit 104 can capture the access address 15a three times. In this case, two of the captured access addresses 15a may be the same, meaning there is an access address 15a with the highest frequency of occurrence. Therefore, the second generation unit 104 uses one or more access addresses 15a with the highest frequency of occurrence as the row hammer address 14a.

[0064] It is understandable that if the number of random units 102 is less than 3, then in one row hammer refresh cycle, the second generation unit 104 can only capture access address 15a at most twice, and at this time there is no access address 15a with the highest frequency. In some embodiments, when the second generation unit 104 cannot determine the access address 15a with the highest frequency in one row hammer refresh cycle (such as when all captured access addresses 15a have the same frequency, or when no access address 15a is captured in one row hammer refresh cycle), an address line can be randomly selected as the row hammer address 14a.

[0065] In some embodiments, the number of enabled random units 102 can be adjusted based on ambient temperature, thereby adjusting the number of access addresses 15a captured in one row hammer refresh cycle. For example, when the ambient temperature is high, the row hammer refresh cycle is short; in this case, the number of enabled random units 102 is reduced, resulting in a decrease in the number of access addresses 15a captured in one row hammer refresh cycle. When the ambient temperature is low, the row hammer refresh cycle is long; in this case, the number of enabled random units 102 is increased, resulting in an increase in the number of access addresses 15a captured in one row hammer refresh cycle.

[0066] In some embodiments, such as Figure 2 As shown, the first generation unit 103 includes: a presampling unit 1031, used to output a presampling pulse 131a, the period of which is consistent with the period of the external pulse signal 10a; a sampling signal generation unit 1032, used to output a sampling signal 132a when the count value 11a is equal to any of the first random numbers 12a; and a sampling pulse generation unit 1033, connected to the presampling unit 1031 and the sampling signal generation unit 1032, used to perform an AND operation on the presampling pulse 131a and the sampling signal 132a to output the sampling pulse 13a.

[0067] In this embodiment of the application, the first generation unit 103 further includes a pre-sampling unit 1031, a sampling signal generation unit 1032, and a sampling pulse generation unit 1033.

[0068] The presampling unit 1031 receives an external pulse signal 10a and generates and outputs a presampling pulse 131a based on the falling edge of the external pulse signal 10a. The period of the presampling pulse 131a is consistent with the period of the external pulse signal 10a. It is understood that the presampling unit 1031 can also generate and output the presampling pulse 131a based on the rising edge of the external pulse signal 10a. In some embodiments, the presampling unit 1031 receives a delayed external pulse signal 10a, such that the rising edge of the presampling pulse 131a is aligned with the rising edge of the sampled signal 132a.

[0069] The sampling signal generation unit 1032 includes multiple logic gates and is connected to the counting unit 101 and multiple random units 102. The sampling signal generation unit 1032 outputs a sampling signal 132a when the count value 11a is equal to any first random number 12a.

[0070] The sampling pulse generation unit 1033 is connected to the presampling unit 1031 and the sampling signal generation unit 1032. The sampling pulse generation unit 1033 performs an AND operation on the received presampling pulse 131a and the sampling signal 132a to output the sampling pulse 13a when the level states of the presampling pulse 131a and the sampling signal 132a are the same. It can be understood that the sampling pulse generation unit 1033 can be connected to the presampling unit 1031 and the sampling signal generation unit 1032 via a NAND gate, and then inverted via an inverter. Since the NAND gate circuit is relatively simple, it is beneficial for simplifying design and saving costs.

[0071] like Figure 3 As shown in the embodiment of this application, a refresh method is provided, including:

[0072] Step S10: Count the received external pulse signal 10a and reset the count value 11a in response to the row hammer refresh command RHR; generate and output a first random number 12a before outputting the count value 11a;

[0073] Step S20: Obtain the count value 11a and a plurality of the first random numbers 12a; when the count value 11a is equal to any of the first random numbers 12a, output a sampling pulse 13a;

[0074] Step S30: When the sampling pulse 13a is received, the corresponding access address 15a is obtained, and a row hammer address 14a is generated based on at least one of the obtained access addresses 15a;

[0075] Step S40: In response to the next row hammer refresh command RHR, refresh at least one row address adjacent to the row hammer address 14a.

[0076] In this embodiment, in response to the hammer refresh command RHR, the number of pulses of the external pulse signal 10a is counted to generate a count value 11a. Before outputting the count value 11a, multiple different first random numbers 12a are generated. In response to the next hammer refresh command RHR, the count value 11a is reset and the first random number 12a is updated. Exemplarily, after receiving the hammer refresh command RHR, the count value 11a changes continuously as the number of pulses of the received external pulse signal 10a increases, while the first random number 12a remains unchanged. After receiving the next hammer refresh command RHR, the count value 11a is reset and the first random number 12a is updated. That is, between two hammer refresh commands RHR, i.e., within one hammer refresh cycle, multiple different first random numbers 12a are generated only once.

[0077] In this embodiment, after generating a count value 11a and multiple first random numbers 12a, the count value 11a and multiple first random numbers 12a are obtained, wherein the multiple first random numbers 12a at the same time can be different. When the count value 11a is equal to any of the first random numbers 12a, a sampling pulse 13a is output. Exemplarily, a pseudo-random number is generated by an LFSR to generate the first random number 12a. The pseudo-random number generated by the LFSR can be directly used as the first random number 12a. By setting the initial values ​​of multiple LFSRs to different values, the multiple pseudo-random numbers generated by multiple LFSRs at the same time can be different, that is, the multiple first random numbers 12a are different; optionally, the multiple pseudo-random numbers can also be subjected to certain operations to generate multiple different first random numbers 12a. In addition, optionally, if two identical first random numbers 12a are obtained in a hammer refresh cycle, an excitation signal can be generated to regenerate one of the repeated first random numbers 12a until multiple different first random numbers 12a are obtained. In this case, a certain first random number 12a may be generated multiple times in a hammer refresh cycle. In some embodiments, a circuit with multiple logic gates can be used to compare the count value 11a with each first random number 12a, and when the count value 11a at a certain moment is equal to any first random number 12a, a sampling pulse 13a is output.

[0078] In this embodiment, upon receiving a sampling pulse 13a, the corresponding access address 15a is captured, and a hammer address 14a is generated based on the captured at least one access address. Exemplarily, at a certain moment during a hammer refresh cycle, the count value 11a equals any first random number 12a, at which point a sampling pulse 13a is received to capture the access address 15a. Then, based on the at least one access address 15a captured during a hammer refresh cycle, the hammer address 14a is determined. In some embodiments, the access address 15a with the highest frequency among the captured access addresses 15a can be used as the hammer address 14a. Thus, by generating multiple different first random numbers 12a, at least one access address 15a can be randomly captured within the hammer refresh cycle, increasing the randomness and uniformity of the captured address, thereby improving the accuracy of the generated hammer address 14a and reducing data errors and data loss caused by the hammer effect.

[0079] In this embodiment, in response to the next row hammer refresh command RHR, at least one row address adjacent to row hammer address 14a is refreshed, where the at least one row address adjacent to row hammer address 14a is the victim row. Optionally, depending on the performance and power consumption requirements of the refresh circuit and memory, one row address adjacent to row hammer address 14a can be selected for refresh to reduce power consumption; alternatively, multiple, or even all, adjacent row addresses can be selected for refresh to improve the accuracy of refreshing the victim row.

[0080] In some embodiments, generating a first random number 12a before outputting the count value 11a further includes: adjusting the maximum random value of the first random number 12a based on the ambient temperature.

[0081] In some embodiments, adjusting the maximum random value of the first random number 12a based on ambient temperature includes: generating n second random numbers in response to the row hammer refresh command RHR; outputting the sum of the m generated second random numbers based on ambient temperature as the first random number 12a; wherein n≥m≥1; or, outputting one second random number based on ambient temperature as the first random number 12a.

[0082] In this embodiment, n second random numbers are generated based on the received row hammer refresh command RHR, where n is an integer greater than or equal to 1, and the second random numbers can be pseudo-random numbers. For example, based on different ambient temperatures, the sum of m of the n second random numbers can be output as the first random number 12a, where n ≥ m ≥ 1; or one of the second random numbers can be directly output as the first random number 12a. In some embodiments, it can also be detected whether the generated multiple first random numbers 12a are all different; if there is a duplicate first random number 12a, the corresponding first random number 12a is regenerated.

[0083] In some embodiments, when the ambient temperature is high, one of the second random numbers is directly output as the first random number 12a, and the maximum value of the first random number 12a is small. When the ambient temperature is low, the sum of m second random numbers is output as the first random number 12a, and the maximum value of the first random number 12a is large. This ensures that the number of times the count value 11a equals any of the first random numbers 12a remains unchanged under different temperatures, i.e., the number of access addresses 15a captured remains unchanged, and uniformity is maintained.

[0084] In some embodiments, the refresh method further includes: detecting the ambient temperature; outputting different temperature flag signals 16a based on the ambient temperature, wherein different temperature flag signals 16a are used to characterize different ambient temperatures; adjusting the maximum random value of the first random number 12a based on the ambient temperature includes: adjusting the maximum random value of the first random number 12a based on the temperature flag signal 16a.

[0085] In some embodiments, the refresh method further includes: adjusting the maximum count value of the count value 11a based on the ambient temperature.

[0086] In this embodiment, the maximum count value can be adjusted based on the ambient temperature represented by the temperature flag signal 16a to correspond to the maximum random value of the first random number 12a. In some embodiments, the maximum count value can be adjusted in real time according to the ambient temperature. In some embodiments, when the count value 11a reaches the maximum count value, the system can enter a sleep state to save power consumption.

[0087] In some embodiments, the ambient temperature includes a first temperature range and a second temperature range; counting the received external pulse signal 10a includes: counting the external pulse signal 10a based on the ambient temperature in the first temperature range to generate a first count value; counting the external pulse signal 10a based on the ambient temperature in the second temperature range to generate a second count value; one of the first count value and the second count value is selected as the count value 11a, and the maximum count values ​​of the first count value and the second count value are different.

[0088] It is understandable that the ambient temperature may include more than two temperature ranges, and the corresponding count value 11a is generated based on different temperature ranges.

[0089] In some embodiments, the period of the external pulse signal 10a is related to 2. k The product of -1 is less than the minimum period of the row hammer refresh; k is the number of binary bits of the first random number 12a.

[0090] In some embodiments, the number of the first random number 12a is greater than or equal to 3; generating the row hammer address 14a based on at least one of the obtained access addresses 15a includes: generating the row hammer address 14a based on one or more access addresses 15a that appear most frequently among the obtained access addresses 15a.

[0091] like Figure 4As shown, this application embodiment also provides a refresh circuit 200, including: a counting unit 201, used to count received external pulse signals 20a and reset the count value 21a in response to a row hammer refresh command RHR; a random unit 202, used to generate a first random number 22a before the counting unit 201 outputs the count value 21a; and a first generation unit 203, connected to the counting unit 201 and the plurality of random units 202, used to obtain the count value 21a generated by the counting unit 201 and the plurality of the first random numbers 22a generated by the plurality of random units 202, respectively. The first random number 22a generated by the random unit 202 is different; the first generation unit 203 is also used to output a sampling pulse 23a when the count value 21a is equal to any of the first random numbers 22a; the second generation unit 204 is connected to the output terminal of the first generation unit 203 and is used to obtain the corresponding access address 25a when the sampling pulse 23a is received, and to generate a row hammer address 24a based on at least one of the obtained access addresses; the refresh unit 205 is used to refresh at least one row address adjacent to the row hammer address 24a in response to the next row hammer refresh command RHR.

[0092] In this embodiment of the application, the counting unit 201 and the plurality of random units 202 also receive a temperature flag signal built into the memory ( Figure 4 (Not shown in the image), the temperature indicator signal is used to characterize whether the ambient temperature is in a high or low temperature range. The counting unit 201 includes a first counting unit 2011 and a second counting unit 2012. The first counting unit 2011 is an i-bit counter, and the second counting unit 2012 is an i+1-bit counter. Taking i=3 as an example, the maximum count value of the first counting unit 2011 is 7, and the maximum count value of the second counting unit 2012 is 15. The counting unit counts the external pulse signal 20a, which is a square wave pulse signal generated by a ring oscillator, with a period of t. The counting unit 201 also resets upon receiving the hammer refresh command RHR, resetting the count value 21a to 0. Multiple random units 202 include four first random units 2021 and four second random units 2022. Both the first random units 2021 and the second random units 2022 are k-bit LFSRs and generate pseudo-random numbers based on the hammer refresh command RHR. The minimum period of the hammer refresh is tRHR. min Condition 2 is met k *t>tRHR min >(2 k -1)*t,tRHR min That is, the time interval between two hammer refreshes at the highest temperature.

[0093] Taking k=3 as an example, the pseudo-random numbers output by the first random unit 2021 and the second random unit 2022 are both in the range of 1 to 7. The initial values ​​of the four first random units 2021 are all different, and the initial values ​​of the four second random units 2022 are also different, so that at the same time, the four pseudo-random numbers generated by the four first random units 2021 are all different, and the four pseudo-random numbers generated by the four second random units 2022 are also different.

[0094] The first generation unit 203 includes a presampling unit 2031, a sampling signal generation unit 2032, and a sampling pulse generation unit 2033. The sampling signal generation unit 2032 outputs a sampling signal 232a when the count value 21a equals any first random number 22a. It is worth noting that both the count value 21a and the first random number 22a are binary numbers. Each bit of the three-bit first random number 22a and its corresponding bit of the three-bit count value 21a are XORed, and the three results are then set to mat. <0> mat <1> and mat <2> The input is passed to a NOR gate (nor), then to an OR gate (or), which compares multiple first random numbers 22a with a count value 21a. Therefore, when the count value 21a equals any first random number 22a, the corresponding XOR gate outputs the mat value. <0> mat <1> and mat <2> If the value is 0, the corresponding OR gate outputs 1, and the OR gate ultimately outputs 1, i.e., the output sampled signal 232a.

[0095] The presampling unit 2031 outputs a presampling pulse 231a based on the falling edge of the external pulse signal 20a; the sampling pulse generation unit 2033 outputs a sampling pulse 23a when the presampling pulse 231a and the sampling signal 232a are at the same level. In some embodiments, the first generation unit 203 further includes a delay unit 2034, which is connected between the ring oscillator and the presampling unit 2031, and is used to delay the external pulse signal 20a input to the presampling unit 2031, thereby delaying the generated presampling pulse 231a to prevent the presampling pulse 231a from missing the slower-generating sampling signal 232a.

[0096] When the ambient temperature is in a high-temperature range, such as Figure 5The timing diagram shows that the first counting unit 2011 counts the external pulse signal 20a and outputs a count value 21a. The pseudo-random numbers generated by the four first random units 2021 are directly used as the first random number 22a. When the count value 21a equals any of the first random numbers 22a, the sampling signal 232a is high. The first generation unit 203 performs an AND operation on the sampling signal 232a and the pre-sampling pulse 231a; that is, when both the pre-sampling pulse 231a and the sampling signal 232a are high, it outputs the sampling pulse 23a to sample the access address 25a. It can be understood that, due to the use of four first random units 2021, the access address 25a can be captured a maximum of four times within one row hammer refresh cycle. It is worth noting that... Figure 5 In the process, the ambient temperatures corresponding to the three hammer refresh cycles tRHR1, tRHR2, and tRHR3 are different, and the higher the ambient temperature, the shorter the hammer refresh cycle tRHR.

[0097] When the ambient temperature is in a low range ( Figure 5 (Timing diagram not shown for this case) The second counting unit 2012 counts the external pulse signal 20a and outputs a count value 21a. The result of adding the pairwise pseudo-random numbers generated by the first random unit 2021 and the second random unit 2022 is used as the first random number 22a. When the count value 21a is equal to any of the first random numbers 22a, the sampling signal 232a is at a high level. It can be understood that at this time, the maximum count value of the count value 21a is 15, and the maximum random value of the first random number 22a is 14. Therefore, compared with the case where the ambient temperature is in a high-temperature range, both the maximum count value and the maximum random value are increased to ensure that the number of access addresses 25a captured remains unchanged under different temperatures and to maintain uniformity.

[0098] Thus, on the one hand, by generating multiple different first random numbers 22a, at least one access address 25a can be randomly captured within the row hammer refresh cycle, increasing the randomness of the captured address and thereby improving the accuracy of the generated row hammer address 24a, reducing data errors and data loss caused by the row hammer effect. On the other hand, adjusting the maximum count value and the maximum random value based on different temperatures ensures better uniformity of capturing access addresses 25a at different temperatures.

[0099] like Figure 6 As shown, this application embodiment also provides a memory 300, including: a memory cell array 301; and a peripheral circuit 302 coupled to the memory cell array 301; the peripheral circuit 302 includes any of the refresh circuits described in the above embodiments. This increases the randomness of the fetched access address, improves the accuracy of the generated row hammer address, and reduces memory data errors and data loss caused by the row hammer effect.

[0100] like Figure 7 As shown in the illustration, this application also provides a storage system 400, including: a memory 401, including any of the refresh circuits described in the above embodiments; and a controller 402 coupled to the memory 401; the controller 402 is used to control the memory 401. This can increase the randomness of the fetched access address, improve the accuracy of the generated row hammer address, reduce memory data errors and data loss caused by the row hammer effect, and improve the stability of the storage system.

[0101] It should be noted that the features disclosed in the several method or device embodiments provided in this application can be arbitrarily combined to obtain new method or device embodiments without conflict.

[0102] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A refresh circuit, characterized in that, include: The counting unit is used to count the received external pulse signals and reset the count value in response to the line hammer refresh command; A random unit is used to generate a first random number before the counting unit outputs the count value; A first generation unit is connected to the counting unit and the plurality of random units, and is used to obtain the count value generated by the counting unit and the plurality of first random numbers generated by the plurality of random units, wherein the first random numbers generated by different random units are different; The first generation unit is further configured to output a sampling pulse when the count value is equal to any of the first random numbers; The second generation unit is connected to the output of the first generation unit and is used to obtain the corresponding access address when the sampling pulse is received, and to generate a row hammer address based on at least one of the obtained access addresses. A refresh unit is used to respond to the next row hammer refresh command and refresh at least one row address adjacent to the row hammer address; The random unit is also used to adjust the maximum random value of the first random number based on the ambient temperature.

2. The refresh circuit according to claim 1, characterized in that, The random unit includes n pseudo-random number units, each of which is used to generate a second random number in response to the row hammer refresh command; The random unit is used to output the sum of m second random numbers generated based on the ambient temperature, as the first random number; where n≥m≥1; or, The random unit is used to output a second random number based on the ambient temperature, which is then used as the first random number.

3. The refresh circuit according to claim 1 or 2, characterized in that, include: A temperature detection module is used to detect the ambient temperature. A temperature flag module is used to output different temperature flag signals based on the ambient temperature, and the different temperature flag signals are used to characterize that the refresh circuit is at different ambient temperatures. The random unit is also used to receive the temperature flag signal and to adjust the maximum random value of the first random number based on the temperature flag signal.

4. The refresh circuit according to claim 3, characterized in that, The counting unit has a maximum count value, and the counting unit is also used to adjust the maximum count value based on the ambient temperature.

5. The refresh circuit according to claim 4, characterized in that, The ambient temperature includes a first temperature range and a second temperature range. The counting unit includes a first counting unit and a second counting unit. The maximum count value of the first counting unit is different from the maximum count value of the second counting unit. The first counting unit is enabled based on the ambient temperature in the first temperature range, and the second counting unit is enabled based on the ambient temperature in the second temperature range. The first counting unit and the second counting unit select one pair to count the external pulse signal to generate the count value.

6. The refresh circuit according to claim 1, characterized in that, The product of the period of the external pulse signal and 2k-1 is less than the minimum period of the row hammer refresh; k is the number of binary bits of the random unit.

7. The refresh circuit according to claim 1, characterized in that, The number of random units is greater than or equal to 3; The second generation unit is specifically used to generate the row hammer address based on one or more access addresses that appear most frequently among the acquired access addresses.

8. The refresh circuit according to claim 1, characterized in that, The first generation unit includes: A presampling unit is used to output a presampling pulse, the period of which is consistent with the period of the external pulse signal; A sampling signal generation unit is configured to output a sampling signal when the count value is equal to any of the first random numbers; A sampling pulse generation unit, connected to the presampling unit and the sampling signal generation unit, is used to perform an AND operation on the presampling pulse and the sampling signal to output the sampling pulse.

9. A refresh method, characterized in that, include: The received external pulse signals are counted, and the count value is reset in response to the row hammer refresh command; Generate and output multiple distinct first random numbers before outputting the count value; Obtain the count value and multiple first random numbers; A sampling pulse is output when the count value equals any of the first random numbers; Upon receiving the sampling pulse, the corresponding access address is obtained, and a row hammer address is generated based on at least one of the obtained access addresses; In response to the next row hammer refresh command, refresh at least one row address adjacent to the row hammer address; The step of generating a first random number before outputting the count value further includes: The maximum random value of the first random number is adjusted based on the ambient temperature.

10. The method according to claim 9, characterized in that, The adjustment of the maximum random value of the first random number based on ambient temperature includes: In response to the row hammer refresh command, n second random numbers are generated; The sum of m second random numbers generated based on the ambient temperature is output as the first random number; where n≥m≥1; or, A second random number is output based on the ambient temperature, which is used as the first random number.

11. The method according to claim 9 or 10, characterized in that, Also includes: Detect the ambient temperature; Based on the ambient temperature, different temperature indicator signals are output, and the different temperature indicator signals are used to characterize different ambient temperatures; The maximum random value of the first random number adjusted based on ambient temperature includes: The maximum random value of the first random number is adjusted based on the temperature flag signal.

12. The method according to claim 11, characterized in that, Also includes: The maximum count value is adjusted based on the ambient temperature.

13. The method according to claim 12, characterized in that, The ambient temperature includes a first temperature range and a second temperature range; The counting of received external pulse signals includes: Based on the ambient temperature within the first temperature range, the external pulse signal is counted to generate a first count value; Based on the ambient temperature within the second temperature range, the external pulse signal is counted to generate a second count value; One of the first count value and the second count value is selected as the count value, and the maximum count values ​​of the first count value and the second count value are different.

14. The method according to claim 9, characterized in that, The product of the period of the external pulse signal and 2k-1 is less than the minimum period of the row hammer refresh; k is the number of binary bits of the first random number.

15. The method according to claim 9, characterized in that, The number of the first random numbers is greater than or equal to 3; The step of generating a row hammer address based on at least one of the obtained access addresses includes: The hammer address is generated based on one or more of the most frequently occurring access addresses among the obtained access addresses.

16. A memory, characterized in that, include: Storage cell array; Peripheral circuitry, coupled to the memory cell array; The peripheral circuit includes the refresh circuit as described in any one of claims 1 to 8.

17. A storage system, characterized in that, include: The memory includes the refresh circuitry as described in any one of claims 1 to 8; The controller is coupled to the memory; The controller is used to control the memory.

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