Abstract: A semiconductor memory device includes a memory array configured to include memory cells for storing input data and Code Address Memory (CAM) cells for storing setting data used to set an operation condition; an operation circuit configured to perform a CAM read operation by supplying a read voltage to the CAM cells, perform a test operation for detecting unstable CAM cells in each of which a difference between a threshold voltage and the read voltage is smaller than a permitted limit, from among the CAM cells, and perform an erase operation or a program operation for the unstable CAM cells; and a controller configured to control the operation circuit so that the program operation for storing the setting data in the unstable CAM cells is performed if the number of unstable CAM cells detected in the test operation is greater than a permitted value.

Abstract: A multi-wafer CAM cell in which the negative effects of increased travel distance have been substantially reduced is provided. The multi-wafer CAM cell is achieved in the present invention by utilizing three-dimensional integration in which multiple active circuit layers are vertically stack and vertically aligned interconnects are employed to connect a device from one of the stacked layers to another device in another stack layer. By vertically stacking multiple active circuit layers with vertically aligned interconnects, each compare port of the inventive CAM cell can be implemented on a separate layer above or below the primary data storage cell. This allows the multi-wafer CAM structure to be implemented within the same area footprint as a standard Random Access Memory (RAM) cell, minimizing data access and match compare delays.

Abstract: An apparatus and a method of operating the apparatus. The apparatus includes a driver circuit and a memory circuit. The driver circuit may be configured to precharge a hitline in response to a predetermined voltage level and a control signal and sense a result of a compare operation based upon a hitline signal on the hitline. The driver circuit generally precharges the hitline to a voltage level lower than the predetermined voltage level and senses the result of the compare operation using the full predetermined voltage level. The memory circuit may be configured to perform the compare operation using the hitline.

Abstract: Content-Addressable Memory (CAM) arrays and related circuitry for integrated circuits and CAM array comparison methods are provided such that relatively low power is used in the operation of the CAM circuitry. A binary value pair is stored in a pair of CAM memory elements. A comparison signal is provided to comparator circuitry that uniquely represents the stored binary values. A match signal is input to the comparator circuitry that uniquely represents a binary value pair to be compared with the stored binary value pair. In one example, a transistor is operated to output a positive match result signal only on a condition that the comparison signal provided to the comparator circuitry and match signal input to the comparator circuitry represent the same binary value pair. In that example, no transistor of the comparator circuitry is operated when the comparison signal provided to the comparator circuitry and match signal input to the comparator circuitry represent different binary value pairs.

Abstract: Embodiments of a Content Addressable Memory (CAM) enabling high-speed search and invalidate operations and methods of operation thereof are disclosed. In one embodiment, the CAM includes a CAM cell array including a number of CAM cells and a valid bit cell configured to generate a match indicator, and blocking circuitry configured to block an output of the valid bit cell from altering the match indicator during an invalidate process of a search and invalidate operation. Preferably, the output of the valid bit cell is blocked from affecting the match indicator for the CAM cell array beginning at a start of the invalidate process and continuing until an end of the search and invalidate operation.

Abstract: A content search system including a CAM device having a plurality of CAM blocks and a governor logic receives a search request and compares the number of CAM blocks required to perform the requested search to a limit number, the limit number being the maximum number of CAM blocks permitted to be used in a requested search operation. If the number of CAM blocks required to perform the requested search exceeds the maximum number of CAM blocks permitted to be used in a requested search operation, then the search operation is rejected. The governing operation can be performed on each requested search, thus limiting power dissipation. The relationship between a maximum number of CAM blocks and power dissipation can be characterized, and a corresponding block limit value can be stored into a memory accessible by governor logic.

Abstract: Array area and power consumption are reduced in a content addressable memory. A comparator for performing a match determination and a size determination is provided commonly for plural entries each storing data to be retrieved. Each entry includes data storage cells for storing data and mask cells for storing mask bits. The number of mask cells is smaller than that of the data storage cells. Search data is transmitted to the comparator via a search data bus. One of the entries is selected according to a predetermined rule. The comparator decodes the mask bits, generates a mask instruction signal, and performs match comparison and size comparison between the search data and data to be retrieved which is stored in the selected entry.

Abstract: Ternary CAM cells include a compare circuit including a discharge path having only two pull-down transistors coupled between the match line and ground potential.

Abstract: A content addressable memory chip which can perform a high speed search with less error is provided. A match amplifier zone determines coincidence or non-coincidence of search data with data stored in the content addressable memory cells in an entry of a CAM cell array, according to the voltage of a match line. The match amplifier zone comprises one or more NMOS transistors and one or more PMOS transistors. The match amplifier zone has a dead zone to an input of a voltage of the match line, and has a property that no flow-through current is present in the match amplifier zone.

Abstract: A content-addressable memory (CAM) for managing the reallocation of erasable objects within a non-volatile memory is conceptually separated into two tables: a first table provides verification of whether or not a logical address has been reallocated and, if so, a second table provides the physical address of the reallocated erasable object.

Abstract: According to one disclosed embodiment, a content addressable memory (CAM) system configured for reduced power consumption and increased speed includes a plurality of bit cells implementing a stacked architecture. Each bit cell comprises a pair of stacked storage elements in a first column and a compare circuit, coupled to the pair of stacked storage elements and a matchline of the CAM system, situated in a second column. The stacked architecture results in a reduced matchline length, thereby reducing CAM system power consumption and increasing CAM system speed. In a further embodiment, a content addressable memory (CAM) system configured for reduced power consumption and increased speed includes storing encoded data in a pair of stacked storage elements.

Abstract: A memory structure and method to fabricate the same is described. The memory structure includes a first memory cell having a first pair of non-volatile portions. The memory structure also includes a second memory cell having a second pair of non-volatile portions. The first and second pairs of non-volatile portions are disposed in an inter-locking arrangement.

Abstract: There is a need to highly integrate a circuit area of content addressable memory (CAM) and ensure faster operation thereof. A priority encoder and row decoder portion shares a row address register including more than one row. Each row of the row address register corresponds to each entry of a TCAM array mat and retains each address. Each row of the row address register corresponds to each word line and match line of the TCAM array mat. Writing data to the TCAM array mat activates word line for a row retained in the row address register corresponding to a specified address. Searching for the TCAM array mat activates a match line for the TCAM array mat. The row address register for the corresponding row stores the address of an entry for the TCAM array mat matching search data.

Abstract: A conditionally precharged content addressable memory (CAM) includes forcing a mismatch on a matchline of the CAM if a data entry in the CAM is invalid. The matchline of the CAM is precharged only if the data entry is valid.

Abstract: An integrated circuit having a CAM array includes a plurality of CAM cells organized in rows and columns where each row corresponds to an address word and each column corresponds to a bit position, and a match line for each row connected to be shared by CAM cells in that row. The CAM array also includes a feedback circuit for each row connected to limit a discharge voltage for a corresponding match line in that row. In another aspect, a method of operating an integrated circuit having a CAM array includes organizing a plurality of CAM cells in rows and columns where each row corresponds to an address word and each column corresponds to a bit position, and sharing a match line with CAM cells in each row. The method also includes limiting a discharge voltage for the match line.

Abstract: A semiconductor integrated circuit includes a plurality of output transistors each controlling the magnitude of an output voltage relative to the magnitude of a load current according to a control value indicated by an impedance control signal applied to a control terminal, a voltage monitor circuit outputting an output voltage monitor value indicating a voltage value of the output voltage, and a control circuit controlling the magnitude of the control value according to the magnitude of an error value between a reference voltage indicating a target value of the output voltage and the output voltage monitor value, and controls based on the control value whether any of such transistors be brought to a conducting state. The control circuit increases a change step of the control value relative to the error value during a predetermined period according to prenotification signals for notifying a change of the load current in advance.

Abstract: A CAM circuit includes a plurality of core memory cells, each cell including comparison logic for generating a local match signal based on a comparison between stored data in the cell and a compare value. The CAM circuit includes a plurality of local match lines, each local match line coupled with a corresponding cell and adapted to convey the local match signal generated by the cell. The CAM circuit includes combination logic for receiving respective local match signals generated by a subset of the cells and for generating an output word match signal having a value indicative of the local match signals. The subset of cells is arranged with at least one block having a word size that is limited based on available space for routing tracks used to convey the local match signals and at least one word match signal in a base metal layer across the cells.

Abstract: Quaternary CAM cells are provided that include one or more compare circuits that each has a minimal number of pull-down transistors coupled between the match line and ground potential. For some embodiments, the compare circuit includes two parallel paths between the match line and ground potential, with each parallel path consisting of a single pull-down transistor having a gate selectively coupled to the stored data value in response to a comparand value.

Abstract: A content addressable memory (CAM) system configured for reduced power consumption and increased speed includes a plurality of bit cells implementing a stacked architecture. Each bit cell comprises a pair of stacked storage elements in a first column and a compare circuit, coupled to the pair of stacked storage elements and a matchline of the CAM system, situated in a second column. The stacked architecture results in a reduced matchline length, thereby reducing CAM system power consumption and increasing CAM system speed. In a further embodiment, a content addressable memory (CAM) system configured for reduced power consumption and increased speed includes storing encoded data in a pair of stacked storage elements.

Abstract: A content addressable memory (CAM) device can include a number of bit lines. One or more of the bit lines can be connected to storage circuits of CAM cells in a corresponding column. Each CAM cell can include compare circuits that compare a stored value one or more compare data values. An isolation circuit car have a controllable impedance path connected between the bit line and a precharge voltage node and can be controlled by application of a potential at a control node. A control circuit can be coupled to the control node and can switch the isolation circuit from a high impedance state to a low impedance state prior to, and for a duration of at least of a portion of an access operation.

Abstract: The present invention provides a content addressable memory capable of higher frequency operation than conventional. When a search enable signal supplied from a search control circuit is asserted, each of search line drivers transfers search data to each CAM cell of a CAM memory array via a search line pair. The search line enable signal is transmitted to the search line drivers via a single control signal line coupled to the search control circuit. The control signal line is coupled to the search line drivers in such a manner that the search line enable signal passes through coupling nodes between the search line drivers and the control signal line in an arrangement order of the search line drivers from the side far away as viewed from match amplifiers.

Abstract: An associative memory that can reduce search errors is provided. An associative memory includes R distance/time conversion circuits DT1 to DTR. The R distance/time conversion circuits DT1 to DTR each include a NAND circuit 40 and N bit stages 41 to 4k. The N bit stages 41 to 4k delay a signal from the NAND circuit 40 by longer delay time as the distance between reference data and search data is greater and oscillate the signal. Among R oscillation signals output from the distance/time conversion circuits DT1 to DTR, the earliest changing oscillation signal is detected as an oscillation signal for the Winner row.

Abstract: Searching for patterns stored on a hardware storage device. A method includes, as part of a memory refresh operation, performing a read to read contents of a portion of a memory. The method further includes writing the read contents of the portion of memory back to the portion of memory. The read contents are provided to data comparison logic. Using the data comparison logic; the read contents are compared to predetermined data patterns. A determination is made as to whether or not the contents match at least one of the predetermined data patterns. When the read contents match at least one of the predetermined data patterns, a software readable indicator is provided indicating that the read contents match at least one of the predetermined data patterns. Similar embodiments may be implemented using hard drive head wear leveling operations.

Abstract: A memory includes: memory devices that each store data of one bit; and a read unit that, by using one predetermined memory device of the memory devices that are included in a memory block having a predetermined unit number of the memory devices as an inversion flag device, reads out data of (the predetermined unit number ?1) bits that is written in the other memory devices with the bits being inverted in a case where the data of one bit written in the inversion flag device is a first value representing any one of “0” and “1” and directly reads out the data of (the predetermined unit number ?1) bits that is written in the other memory devices in a case where the data of one bit written in the inversion flag device is a second value other than the first value.

Abstract: A digital design and technique may be used to implement a Manhattan Nearest Neighbor content addressable memory function by augmenting a serial content addressable memory design with additional memory and counters for bit serially accumulating in parallel and subsequently comparing in parallel all the Manhattan distances between a serially inputted vector and all corresponding vectors resident in the CAM. Other distance measures, besides a Manhattan distance, may optionally be used in conjunction with similar techniques and designs.

Abstract: The present invention relates to a binary content addressable memory (CAM), and more particularly, to a binary content addressable memory (CAM) in which the number of transistors constituting the content addressable memory can be reduced to decrease the size of the content addressable memory, thereby increasing the degree of integration and improving power consumption. According to the present invention, since the binary content addressable memory according to the present invention has a smaller number of transistors than those of the conventional binary content addressable memory, a memory can be fabricated in a smaller size, thereby improving the degree of integration as one of most important factors in the memory design. In addition, improvement of the degree of integration contributes to miniaturization and lightweightness of the product in its design.

Abstract: A content addressable memory device capable of making simultaneous pursuit of low power consumption and speeding up is provided. A match amplifier A determines coincidence or non-coincidence of search data and data stored in a content addressable memory in an entry of a memory array A, according to a voltage of a match line MLA. A match amplifier B determines coincidence or non-coincidence of search data and data stored in a content addressable memory in an entry of a memory array B, according to a voltage of a match line MLB. A block-B control circuit directs to start searching in the memory array B after two cycles after searching has been started in the memory array A. A block-B activation control circuit directs to stop searching in the memory array B according to a voltage of the match line MLA after searching in the memory array A.

Abstract: A static CAM includes a plurality of entries E each including a number of CAM cells B and a summary S. Each CAM cell B is associated with a memory cell M and a comparator C. Generally, the CAM receives as input i number of lookup data lines. When data is received, memory cells M provide compared data for corresponding comparators C in CAM cells B to compare the compared data to the received data. If all compared data match all received data lines for an entry, then there is a hit for that entry. But if any compared data does not match the corresponding data line, then there is a miss for that line and therefore a miss for that entry. Depending on applications, the CAM returns an address if there is a hit for one or a plurality of entries.

Abstract: A semiconductor device includes a first memory region including a plurality of memory cells; a test unit configured to test the first memory region, and detect a weak bit from among the plurality of memory cells; and a second memory region configured to store a weak bit address (WBA) of the first memory region, and data intended to be stored in the weak bit, wherein the first memory region and the second memory region include different types of memory cells.

Abstract: A method for comparing content addressable memory (CAM) elements is disclosed. Binary values are stored in a pair of CAM elements. A comparison value is provided to a group of comparators, the comparison value based on the binary value stored in the pair of CAM elements. A match value is provided to the group of comparators, the match value corresponding to a binary value pair to be compared with the binary value stored in the pair of CAM elements. A positive match result value is output from a selected group of comparators via an output line in response to the comparison value matching the match value.

Abstract: The power consumption of a search engine such as a CAM device is dynamically adjusted to prevent performance degradation and/or damage resulting from overheating. For some embodiments, the CAM device is continuously sampled to generate sampling signals indicating the number of active states and number of compare operations performed during each sampling period. The sampling signals are accumulated to generate an estimated device power profile, which is compared with reference values corresponding to predetermined power levels to generate a dynamic power control signal indicating predicted increases in the device's operating temperature resulting from its power consumption. The dynamic power control signal is then used to selectively reduce the input data rate of the CAM device, thereby reducing power consumption and allowing the device to cool.

Abstract: Techniques are described for sum address compare (A+B=K) operation for use in translation lookaside buffers and content addressable memory devices, for example. Address input signals A and B are supplied as input to the A+B=K operation and K is a previous value stored in a plurality of memory cells. In each memory cell, a single logic gate circuit output and its inversion are generated in response to updating the memory cells, wherein each single logic gate circuit has as input an associated memory cell output and a next lowest significant bit adjacent memory cell output. In each of the memory cells, a portion of the A+B=K operation associated with each memory cell is generated in a partial lookup compare circuit wherein the corresponding address input signals A and B are combined with the associated memory cell output and the generated single logic gate circuit output and its inversion during a read lookup compare operation.

Abstract: An entry including multiple bits of unit cells each storing data bit is coupled to a match line. The match line is supplied with a charging current having a restricted current value smaller than a match line current flowing in a one-bit miss state in one entry, but larger than a match line current flowing in an all-bit match state in one entry. A precharge voltage level of a match line is restricted to a voltage level of half a power supply voltage or smaller. Power consumption in a search cycle of a content addressable memory can be reduced, and a search operation speed can be increased.

Abstract: The associative memory comprises a simplified functional processing unit (SFPU), implemented by an LUT logic network, that implements simplified CAM function g, where g is the function derived from CAM function ƒ by replacing the value showing “invalid” with the don't care, an auxiliary memory that stores the inverse function ƒ?1 of said CAM function ƒ; and an output modifier that checks whether the output value of said SFPU is equal to the output value of the CAM function ƒ; wherein the SFPU produces the operational value (“tentative index value”) for the simplified CAM function g; the auxiliary memory produces the value of the inverse function ƒ?1 when the tentative index value is applied; the output modifier compares the input data with the value of the inverse function ƒ?1, and produces the output of said SFPU if they are the same, otherwise produces the signal showing the “invalid”.

Abstract: A design structure including universal peripheral processor architecture on an integrated circuit (IC) includes a first data bus and a second data bus communicating with first and second ternary content addressable memory (TCAM) devices configured as state machines. First and second processors are coupled to the first bus interface logic and the second bus interface logic. First and second data storage devices communicate with the first and second processors and are coupled to the first and second data buses and communicate with each other. The TCAM devices are configured as state machines and are coupled to and adapted to interface with the processors, the data storage devices, and the bus interface logic using predefined protocols.

Abstract: Power consumption of CAM devices is reduced during compare operations between a search key and data stored in the device's array by reducing the amount of electric charge by which the match line is discharged during mismatch conditions. More specifically, for some embodiments, each row of the CAM array includes circuitry that discharges the match line to a virtual ground node rather than to ground potential during mismatch conditions. Because the electrical potential on the virtual ground node is greater than ground potential, power consumption associated with charging the match line back to a logic high state during the next compare operation is reduced.

Abstract: A digital design and technique may be used to implement a Manhattan Nearest Neighbor content addressable memory function by augmenting a serial content addressable memory design with additional memory and counters for bit serially accumulating in parallel and subsequently comparing in parallel all the Manhattan distances between a serially inputted vector and all corresponding vectors resident in the CAM. Other distance measures, besides a Manhattan distance, may optionally be used in conjunction with similar techniques and designs.

Abstract: An offset removal circuit (10) includes a removal circuit (1) and a removal circuit (2). The removal circuit (1) digitally removes offset voltage from an input voltage Vin. The removal circuit (2) removes offset voltage, in an analog manner, from the voltage subjected to offset voltage removal by the removal circuit (1). Then, the removal circuit (2) outputs the voltage subjected to the offset voltage removal to a non-inverting input terminal of a differential amplifier (20).

Abstract: The invention provides a content-addressable memory cell formed by two transistors that are configured so that one of the transistors is for storing a data bit and the other for is storing the complement of the data bit. Each transistor has a back control gate that can be controlled to block the associated transistor. The device also includes a comparison circuit that is configured to operate the first and second transistors in read mode while controlling the back control gate of each of the transistors so as to block the passing transistor if a proposed bit and the stored bit correspond. Then, the presence or absence of current on a source line linked to the source of each of the transistors indicates whether the proposed bit and the stored bit are identical or not. The invention also provides methods for operating the content-addressable memory cells of this invention, as well as content-addressable memories having a plurality of the content-addressable memory cells of this invention.

Abstract: Methods and circuits for CAM cells using PMCs are disclosed herein. In one embodiment, a BCAM cell can include: (i) a first PMC coupled to a first access transistor and a bit node, where the first access transistor is coupled to a true bit line; (ii) a second PMC cell coupled to a second access transistor and the bit node, where the second access transistor is coupled to a complement bit line, and the first and second access transistors are controllable by a word line; (iii) a program enable transistor coupled to the bit node, and configured to couple a program control voltage to the bit node when enabled; and (iv) a match indication transistor configured to discharge a match line in response to states of the true and complement bit lines relative to the bit node.

Abstract: Static-based comparators and methods for comparing data are disclosed. The static-based comparator is configured to selectively switch at least one comparator output in response to a comparison of corresponding data with compare data, and a validity indicator for the data. If the validity indicator indicates valid data, the static-based comparator switches to drive the comparator output indicating either a match or mismatch between corresponding compared data. If the validity indicator indicates invalid data, the static-based comparator provides a mismatch on the comparator output without switching the static-based comparator regardless of whether or not the data matches the compare data. In this manner, the static-based comparator does not dissipate power switching the comparator output for data marked invalid. The static-based comparator can be employed in content addressable memories (CAMs) for comparing one or more bits of tag data to corresponding bit(s) of compare data.

Abstract: To provide a semiconductor device whose power can be turned off without the need for a peripheral circuit for data to escape temporarily and in which stored data is not lost even in an off state of the power of the device, and a memory device including the semiconductor device. In a holding circuit of the semiconductor device, a transistor that includes a semiconductor layer (at least a channel formation region) including an oxide semiconductor material with which small off-state current can be achieved is used. Further, the semiconductor device includes a switching element which enables a comparison circuit in which comparison between data stored in the holding circuit and reference data input from the outside does not need to be performed to become forcibly inactive.

Abstract: An entry including multiple bits of unit cells each storing data bit is coupled to a match line. The match line is supplied with a charging current having a restricted current value smaller than a match line current flowing in a one-bit miss state in one entry, but larger than a match line current flowing in an all-bit match state in one entry. A precharge voltage level of a match line is restricted to a voltage level of half a power supply voltage or smaller. Power consumption in a search cycle of a content addressable memory can be reduced, and a search operation speed can be increased.

Abstract: A package apparatus includes at least one memory chip, a voltage detection circuit configured to make a determination of whether a voltage supplied to the memory chip is a specific voltage or higher, and a controller configured to control an operation of the memory chip based on a result of the determination.

Abstract: The present invention provides a content addressable memory capable of higher frequency operation than conventional. When a search enable signal supplied from a search control circuit is asserted, each of search line drivers transfers search data to each CAM cell of a CAM memory array via a search line pair. The search line enable signal is transmitted to the search line drivers via a single control signal line coupled to the search control circuit. The control signal line is coupled to the search line drivers in such a manner that the search line enable signal passes through coupling nodes between the search line drivers and the control signal line in an arrangement order of the search line drivers from the side far away as viewed from match amplifiers.

Abstract: The address generator has a hash network for producing hashed Y1, which is obtained by hushing X1, to an input vector X=(X1, X2), a tentative address generator Y1 for making an address generation function f(X) to a tentative address A? when no hash collision occurs and otherwise making one of unique addresses A to A?, a data regenerator for producing X?=f?1(A?), a unique address generator for producing A? when X? coincides with X and otherwise producing “invalid value”, a complementary address generator for producing (X) to X, to which the unique address generator produces “invalid value”, and otherwise producing “invalid value”, and an output combiner which produces, when the outputs of the unique address generator and the complementary address generator have values other than the “invalid value”, the values as a unique address A and otherwise produces “invalid value” as A.

Abstract: The present invention is directed to reduce array area and power consumption in a content addressable memory. A comparator for performing a match determination and a size determination is provided commonly for plural entries each storing data to be retrieved. Each entry includes data storage cells for storing data and mask cells for storing mask bits. The number of mask cells is smaller than that of the data storage cells. Search data is transmitted to the comparator via a search data bus. One of the entries is selected according to a predetermined rule. The comparator decodes the mask bits, generates a mask instruction signal, and performs match comparison and size comparison between the search data and data to be retrieved which is stored in the selected entry.

Abstract: A content addressable memory (CAM) unit does not have any in-cell comparator circuitry. The CAM unit includes a memory array, a multiple row decoder, a controller and an output unit. The memory array has storage cells arranged as data rows and complement rows. The multiple row decoder activates more than one row of the memory array at a time and the controller indicates to the multiple row decoder to activate data rows or complement rows as a function of an input pattern to be matched. The output unit indicates which columns generated a signal, the columns matching the pattern.

Abstract: A pair of operator cells each having a series-coupled circuit of first and second transistors is used as a storage unit. To-be-retrieved data and retrieval data are respectively stored in the first and second transistors, and mutually complementary data items are stored in the operator cells of the storage unit. The operator cells supply currents according to the result of an AND operation between the stored data items to corresponding bit lines, and the read data from the storage unit corresponds to the result of an EXOR operation between the retrieval data and the to-be-retrieved data. The currents flowing in the corresponding bit lines are amplified with sense amplifier circuits to drive local match lines. In the individual sub-blocks of an operator cell array, data items having different pattern lengths can be stored. The potentials of the local match lines are selected according to the data pattern lengths, and match retrieval is performed for the data items having the different pattern lengths.

Abstract: A semiconductor memory device includes a memory array configured to include memory cells for storing input data and Code Address Memory (CAM) cells for storing setting data used to set an operation condition; an operation circuit configured to perform a CAM read operation by supplying a read voltage to the CAM cells, perform a test operation for detecting unstable CAM cells in each of which a difference between a threshold voltage and the read voltage is smaller than a permitted limit, from among the CAM cells, and perform an erase operation or a program operation for the unstable CAM cells; and a controller configured to control the operation circuit so that the program operation for storing the setting data in the unstable CAM cells is performed if the number of unstable CAM cells detected in the test operation is greater than a permitted value.