Abstract: A semiconductor device includes: a first read/write amplifier; a second read/write amplifier; a first group of bit lines belonging to the first read/write amplifier; a second group of bit lines belonging to the second read/write amplifier and mixed with the first group of bit lines. One of the first group of bit lines and one of the second group of bit lines are selected in parallel. A reference potential is supplied to at least one of the first non-selected bit lines adjacent to the first selected bit line selected from the first group of bit lines, and to at least one of the second non-selected bit lines adjacent to the second selected bit line selected from the first group of bit lines. At least one of remaining ones of the first and second non-selected bit lines is set into a floating state.

Abstract: A method and circuit for implementing domino static random access memory (SRAM) local evaluation with enhanced SRAM cell stability, and a design structure on which the subject circuit resides are provided. A SRAM local evaluation circuit enabling a read and write operations of an associated SRAM cell group includes true and complement bitlines, a single write data propagation input, a precharge signal, and a precharge write signal. A passgate device is connected between the complement bitline and the write data propagation input. A transistor stack is connected in series with the precharge device between the true bitline and ground. The precharge write signal disables the passgate device connected between the complement bitline and the write data propagation input during a read operation. During write operations, the precharge write signal enables the passgate device connected between the complement bitline and the write data propagation input and activates the transistor stack.

Abstract: A method and circuit for implementing domino static random access memory (SRAM) local evaluation with enhanced SRAM cell stability, and a design structure on which the subject circuit resides are provided. A SRAM local evaluation circuit enabling a read and write operations of an associated SRAM cell group includes true and complement bitlines, true and complement write data propagation inputs, a precharge signal, and a precharge write signal. A respective precharge device is connected between a voltage supply VDD and the true bitline and the complement bitline. A first passgate device is connected between the complement bitline and the true write data propagation input. A second passgate device is connected between the true bitline and the complement write data propagation input. The precharge write signal disables the passgate devices during a read operation. During write operations, the precharge write signal enables the passgate devices.

Abstract: A design structure embodied in a machine readable medium used in a design process for small signal sensing during a read operation of a static random access memory (SRAM) cell includes coupling a pair of complementary sense amplifier data lines to a corresponding pair of complementary bit lines associated with the SRAM cell, and setting a sense amplifier so as to amplify a signal developed on the sense amplifier data lines, wherein the bit line pair remains coupled to the sense amplifier data lines at the time the sense amplifier is set.

Abstract: A content addressable memory (CAM) device and process for searching a CAM. The CAM device includes a plurality of CAM cells, match-lines (MLs), search lines, and ML sense amplifiers. The ML sense amplifiers are capable of self-calibration to their respective thresholds to reduce effects of random device variation between adjacent sense amplifiers.

Abstract: An SRAM and a forming method and a controlling method thereof are provided. The above-mentioned SRAM includes a tracking column, a normal column, a cell voltage control circuit and a cell voltage pull-down circuit. Each of the tracking column and the normal column includes a plurality of memory cells. The cell voltage control circuit is coupled to the tracking column and the normal column for connecting an operation voltage to the two columns before a write operation of the SRAM starts and for disconnecting the operation voltage from the two columns after the write operation starts. The cell voltage pull-down circuit is coupled to the two columns for pulling down the cell voltages of the two columns after the write operation starts and for ceasing pulling down the cell voltage of the normal column when the cell voltage of the tracking column drops down to a predetermined voltage.

Abstract: A semiconductor memory write method which, when writing data at a threshold voltage level in a memory cell, is configured to perform two write operations including a preliminary data write operation of writing temporary data at a threshold voltage level lower than that of the data at the threshold voltage level, and a final data write operation of additionally writing final data at the threshold voltage level, includes making at least one of a write time of the preliminary data write operation, a word-line waiting time of verify read, and a bit-line waiting time of verify read, shorter than that of the final data write operation.

Abstract: A semiconductor device includes a memory cell to and from which data is written and read in accordance with voltage supplied, a power supply circuit generating the voltage supplied to the memory cell, a microcomputer, an external terminal, a surge protection circuit clamping at a predetermined voltage value a voltage supplied to the external terminal, and a first switch circuit switching to output to one of the power supply circuit and the microcomputer a voltage having passed through the surge protection circuit. The power supply circuit includes a voltage conversion circuit changing the magnitude of a voltage received from the first switch circuit, and a second switch circuit switching to supply the memory cell with one of the voltage received from the first switch circuit and the voltage changed in magnitude.

Abstract: A semiconductor integrated circuit includes: an oxide resistance change element, a constant current source circuit supplying a write current to the oxide resistance change element, and a voltage clamper clamping a voltage in a path in which a write current flows. The voltage clamper is arranged in parallel with the path between the constant current source circuit and the oxide resistance change element.

Abstract: A nonvolatile memory apparatus comprises a memory array (102) including plural first electrode wires (WL) formed to extend in parallel with each other within a first plane; plural second electrode wires (BL) formed to extend in parallel with each other within a second plane parallel to the first plane and to three-dimensionally cross the plural first electrode wires; and nonvolatile memory elements (11) which are respectively provided at three-dimensional cross points between the first electrode wires and the second electrode wires, the elements each having a resistance variable layer whose resistance value changes reversibly in response to a current pulse supplied between an associated first electrode wire and an associated second electrode wire; and a first selecting device (13) for selecting the first electrode wires, and further comprises voltage restricting means (15) provided within or outside the memory array, the voltage restricting means being connected to the first electrode wires, for restricting a

Abstract: Systems, circuits and methods for controlling the word line voltage applied to word line transistors in Spin Transfer Torque Magnetoresistive Random Access Memory (STT-MRAM) are disclosed. One embodiment is directed to a STT-MRAM including a bit cell having a magnetic tunnel junction (MTJ) and a word line transistor. The bit cell is coupled to a bit line and a source line. A word line driver is coupled to a gate of the word line transistor. The word line driver is configured to provide a word line voltage greater than a supply voltage below a transition voltage of the supply voltage and to provide a voltage less than the supply voltage for supply voltages above the transition voltage.

Abstract: A memory card includes a non-volatile memory; and a power management unit for receiving an external supply voltage to supply an operating voltage to the non-volatile memory. The power management unit boosts/bypasses the external supply voltage based on whether the external supply voltage is lower than a detection voltage and then outputs the boosted/bypassed voltage as the operating voltage of the non-volatile memory.

Abstract: In a voltage generating circuit for a semiconductor memory device, each of a plurality of reset signal generators individually generates a reset signal in response to one of a plurality of external source voltages. The plurality of external source voltages have different voltage levels. An output voltage generator generates a plurality of output voltages by independently driving each of the plurality of external source voltages in response to a corresponding one of the plurality of reset signals. The output voltage generator outputs the plurality of output voltages through a common output terminal.

Abstract: A semiconductor device, including a word line driver for driving a word line connected to a memory cell in a memory cell array and for resetting the word line when the memory cell changes from an activated to a standby state. The reset level of the word line driver is set when resetting of the word line is performed, and may be switched between first and second potentials. A word line reset level generating circuit varies the amount of negative potential current supply in accordance with memory cell array operating conditions. The semiconductor device includes a plurality of power source circuits, each having an oscillation circuit and a capacitor, for driving the capacitor via an oscillation signal outputted by the oscillation circuit. At least some power source circuits share a common oscillation circuit, and different capacitors are driven via the common oscillation signal.

Abstract: Methods of operating a memory and a memory are disclosed, such as an analog non-volatile memory device and process that reduces the effects of charge leakage from data cache capacitors, maintaining stored charge levels as data. In one embodiment, data values are compensated for leakage that is uniform across the data cache by charging a reference capacitor or initiating another leakage model and uniformly adjusting the ground of the data capacitors by the effect amount or by adjusting an amplifier offset or gain. In another embodiment, held data values are compensated for charge leakage effects that are non-uniform due to data values being sequentially transferred into the data cache by scaling a ground node or adjustment of amplifier offset/gain of each capacitor in the data cache against the leakage reference and the order in which data was transferred into the data cache.

Abstract: A semiconductor storage device has memory cells provided at intersections of word lines and bit lines, a precharge circuit connected to the bit lines, and a write circuit. The write circuit includes a column selection circuit controlled by a write control signal, a transistor for controlling a potential of a selected bit line so that the potential of the selected bit line is a first potential (e.g., 0 V), a capacitance element for controlling the potential of the selected bit line so that the potential of the selected bit line is a second potential (e.g., a negative potential) that is lower than the first potential, and a clamp circuit for clamping the second potential when a power supply voltage becomes high.

Abstract: The present disclosure includes devices, methods, and systems for programming memory, such as resistance variable memory. One embodiment can include an array of resistance variable memory cells, wherein the resistance variable memory cells are coupled to one or more data lines, a row decoder connected to a first side of the array, a column decoder connected to a second side of the array, wherein the second side is adjacent to the first side, a gap located adjacent to the row decoder and the column decoder, and clamp circuitry configured to control a reverse bias voltage associated with one or more unselected memory cells during a programming operation, wherein the clamp circuitry is located in the gap and is selectively coupled to the one or more data lines.

Abstract: A nonvolatile semiconductor memory device can prevent memory characteristics from deteriorating due to IR drop on word or bit lines in a cross-point type memory cell array. The device comprises a word line selection circuit selecting a selected word line from word lines and applying selected and unselected word line voltages to the selected and unselected word lines, respectively, a bit line selection circuit selecting a selected bit line from bit lines and applying selected and unselected bit line voltages to the selected and unselected bit lines, respectively, and voltage control circuits preventing voltage fluctuation of at least either one of the word and bit lines, wherein at least either one of the word and bit lines are connected to the voltage control circuits at a voltage control point positioned at a farthest point from a drive point connected to the word line selection circuit or bit line selection circuit.

Abstract: For realizing high speed flash memory, bit line is multi-divided for reducing parasitic capacitance, so that local bit line is quickly discharged when reading a memory cell and multi-stage sense amps are used, wherein the multi-stage sense amps are composed of a first dynamic circuit serving as a local sense amp connecting to the local bit line through a read transistor, a second dynamic circuit serving as a segment sense amp for reading the local sense amp, and a tri-state inverter serving as an amplify circuit of a global sense amp for reading the segment sense amp. When reading data, a cell current difference is converted to a time difference for differentiating low threshold data and high threshold data by the multi-stage sense amps. And a buffered data path is connected to the global sense amp for achieving fast data transfer. Additionally, alternative circuits and memory cell structures are described.

Abstract: In a particular embodiment, a memory device is disclosed that includes a memory cell including a resistance-based memory element coupled to an access transistor. The access transistor has a first oxide thickness to enable operation of the memory cell at an operating voltage. The memory device also includes a first amplifier configured to couple the memory cell to a supply voltage that is greater than a voltage limit to generate a data signal based on a current through the memory cell. The first amplifier includes a clamp transistor that has a second oxide thickness that is greater than the first oxide thickness. The clamp transistor is configured to prevent the operating voltage at the memory cell from exceeding the voltage limit.

Abstract: A memory includes many memory regions each including a target memory cell, a source line, a bit line and a reading control circuit. The source line is coupled to a first terminal of the target memory cell. The bit line is coupled to a second terminal of the target memory cell. The reading control circuit is for selectively applying a working voltage to the source line.

Abstract: A semiconductor memory device includes an equalizing signal generation circuit comprising a clamping circuit that clamps a voltage level less than the voltage level of a high voltage level by being controlled by the high voltage, and an equalizing signal driver receiving an output signal of the equalizing signal generation circuit as a driving signal.

Abstract: A semiconductor memory device has a data output device. The data output device is provided with a slew rate control unit for detecting the number of transitions of a plurality of output data to output slew rate control information; and an output driving unit for driving the plurality of output data with a pull-up drivability and a pull-down drivability adjusted based on the slew rate control information.

Abstract: A semiconductor memory device comprising: a memory cell array in which memory cells each containing a variable resistive element and a rectifier element connected in series are arranged at intersections of a plurality of first wirings and a plurality of second wirings; and a control circuit for selectively driving said first wirings and said second wirings; wherein said control circuit applies a first voltage to said selected first wiring, and changes said first voltage based on the position of said selected memory cell within said memory cell array to apply a second voltage to said selected second wiring, so that a predetermined potential difference is applied to a selected memory cell arranged at the intersection between said selected first wiring and said selected second wiring.

Abstract: Systems, devices and methods are disclosed, such as a system and method of sensing the voltage on bit lines that, when respective memory cells coupled to the bit lines are being read that compensates for variations in the lengths of the bit lines between the memory cells being read and respective bit line sensing circuits. The system and method may determine the length of the bit lines between the memory cells and the sensing circuits based on a memory address, such as a block address. The system and method then uses the determined length to adjust either a precharge voltage applied to the bit lines or the duration during which the bit lines are discharged by respective memory cells before respective voltages on the bit lines are latched.

Abstract: The claimed subject matter provides systems and/or methods that facilitate programming and reading multi-level, multi-bit memory cells in a memory device. In multi-bit memory cells, programming one element can affect the second element. Certain combinations of elements can cause excessive levels of complementary bit disturb, state dependent non-uniform charge loss, and state dependent program disturb, reducing memory device reliability. Such effects may be pronounced where a high charge level is programmed into a first element while a second element of the same memory cell is unprogrammed. Memory cell elements can be programmed using additional charge levels to mitigate such effects.

Abstract: A sense amplifier includes a reference signal providing unit and an internal sense amplification unit. The reference signal providing unit provides a reference bit line signal in response to a reference control signal. The internal sense amplification unit receives the reference bit line signal and data signals that correspond to the data. The received signals are provided through bit lines connected to the memory cell array. The internal sense amplification unit senses the received reference bit line signal and the data signals and amplifies the sensed signals. The sense amplifier senses data stored in memory cells connected to dummy bit lines of the outmost memory cell array of a semiconductor memory device such that the memory cells that are not used can be used. Accordingly, the design area and cost of the semiconductor memory device can be reduced.

Abstract: Embodiments for an area efficient high performance memory cell comprising a transistor connected to one of a bit line and a bit line bar are disclosed.

Abstract: A sense amplifier section comprises two stages of latch-type sense amplifier circuits, i.e., a primary-stage latch-type sense amplifier and a secondary-stage latch-type sense amplifier, wherein stress exerted on the primary-stage latch-type sense amplifier is reduced significantly to ensure high accuracy in amplification. In the above configuration including the secondary-stage latch-type sense amplifier, when an amplified output from the primary-stage latch-type sense amplifier reaches a predetermined voltage level (e.g., 50 mV), a transition to amplifying operation of the secondary-stage latch-type sense amplifier is enabled so that a time duration of operation of the primary-stage latch-type sense amplifier (corresponding to a time duration of stress exertion on the primary-stage latch-type sense amplifier) can be shortened significantly.

Abstract: A semiconductor integrated circuit includes a plurality of memory cells arranged in a matrix, a plurality of word lines corresponding to respective rows of the plurality of memory cells, a plurality of word line drivers for driving the plurality of word lines, respectively, and a plurality of pull-down circuits connected to the plurality of word lines, respectively, for causing voltages of the respective connected word lines to be lower than or equal to a power supply voltage when the respective word lines are in an active state. The word line drivers each have a transistor for causing the corresponding word line to go into the active state. The pull-down circuits each have a pull-down transistor for pulling down the corresponding word line, the pull-down transistor being a transistor having the same conductivity type as that of the transistor included the word line driver for driving the corresponding word line.

Abstract: Systems and methods of controlled value reference signals of resistance based memory circuits are disclosed. In a particular embodiment, a circuit device is disclosed that includes a first input configured to receive a reference control signal. The circuit device also includes an output responsive to the first input to selectively provide a controlled value reference voltage to a sense amplifier coupled to a resistance based memory cell.

Abstract: A plurality of memory cells, each including a variable resistance element capable of having four or more values, are arranged at intersections of first wirings and second wirings. A control circuit selectively drives the first and second wirings. A sense amplifier circuit compares, with a reference voltage, a voltage generated by a current flowing through a selected memory cell. A reference voltage generation circuit includes: a resistance circuit including first and second resistive elements connected in parallel. Each of the first resistive elements has a resistance value substantially the same as a maximum resistance value in the variable resistance elements, and each of the second resistive elements has a resistance value substantially the same as a minimum resistance value in the variable resistance elements. A current regulator circuit averages currents flowing through the first and second resistive elements.

Abstract: A sense amplifier has a transimpedance amplifier capable of producing an output voltage level proportionate to a current variation sensed going into a bitline. A transconductance device is configured to produce varying bitline current in response to the transimpedance amplifier output voltage. The transconductance device is capable of utilizing the transimpedance amplifier output voltage as feedback to produce a bitline clamp voltage level. The transimpedance amplifier configured to produce an output voltage proportionate to a cell current of a selected memory cell and provide an output signal corresponding to a memory cell state. An output amplifier is coupled to the transimpedance amplifier and capable of producing an output signal level proportionate to the transimpedance amplifier output voltage.

Abstract: A nonvolatile memory device includes multiple memory blocks divided into multiple memory block groups. Each memory block group includes at least two memory blocks of the multiple memory blocks. The nonvolatile memory device also includes a main word line common to the memory blocks, and multiple sub-word lines corresponding to the memory blocks. Sub-word lines of the multiple sub-word lines located within the same memory block group are electrically connected to each other, and sub-word lines of the multiple sub-word lines located in different memory block are electrically isolated from each other.

Abstract: A method and apparatus for multiple string searching using a ternary content addressable memory. For one embodiment, the method includes receiving a text string having a plurality of characters and performing an unanchored search of a database of a stored patterns matching one or more characters of the text string using a state machine, wherein the state machine comprises a ternary content addressable memory (CAM) and wherein the performing comprises comparing a state and one of the plurality of characters with contents of a state field and a character field, respectively, stored in the ternary CAM. In various embodiments, one or more of the following search features may be supported: exact string matching, inexact string matching, single character wildcard matching, multiple character wildcard matching, case insensitive matching, parallel matching and rollback.

Abstract: A variable resistance memory device includes a memory cell connected to a bit line and a clamp circuit configured to provide either a first read voltage or a second read voltage to the bit line according to an elapsed time from a write operation of the memory cell. Related methods are also described.

Abstract: A semiconductor memory device including: a memory cell coupled to a bit line via a select gate transistor; a sense amplifier configured to have a current source for supplying current to the bit line, and detect cell current of the memory cell flowing on the bit line; and a select gate line driver configured to drive the select gate transistor so as to keep the memory cell applied with substantially constant drain-source voltage independently of the bit line resistance at a read time.

Abstract: One embodiment of the present invention sets forth a high-speed single-ended memory read circuit that overcomes performance limitations of conventional single ended memory read circuits. A bit line keeper control mechanism for the high-speed single-ended memory read circuit is disclosed that automatically configures the bit line keeper for high-speed operation or low-speed operation, based on the frequency of a system clock. In high-speed operation, the bit line keeper is disabled, thereby eliminating short-circuit currents related to the bit line keeper and increasing the read performance of the single-ended memory read circuit. In low-speed operation, the bit line keeper is periodically disabled by a timer circuit to enable efficient read or write operations. Subsequent to the read or write operation, the bit line keeper is enabled to preserve state on the bit lines. By selectively enabling the bit line keeper, high-speed performance is improved while preserving correct function at low speeds.

Abstract: A read circuit for reading at least one memory cell adapted to storing a logic value, the at least one memory cell including: a storage element made of a phase-change material; and an access element for coupling the storage element to the read circuit in response to a selection of the memory cell, the read circuit including: a sense current supply arrangement for supplying a sense current to the at least one memory cell; and at least one sense amplifier for determining the logic value stored in the memory cell on the basis of a voltage developing thereacross, the at least one sense amplifier comprising a voltage limiting circuit for limiting the voltage across the memory cell for preserving the stored logic value, wherein the voltage limiting circuit includes a current sinker for sinking a clamping current, which is subtracted from the sense current and depends on the stored logic value.

Abstract: A nonvolatile semiconductor memory device comprises a memory cell array including first and second mutually crossing lines and electrically erasable programmable memory cells arranged at intersections of the first and second lines, each memory cell containing a variable resistor operative to nonvolatilely store the resistance thereof as data and a first non-ohmic element operative to switch the variable resistor; and a clamp voltage generator circuit operative to generate a clamp voltage required for access to the memory cell and applied to the first and second lines. The clamp voltage generator circuit has a temperature compensation function of compensating for the temperature characteristic of the first non-ohmic element.

Abstract: An SRAM device include: a latch unit for retaining data; one or more pass gate transistors controlled by a word line for coupling the latch unit to a bit line and a complementary bit line; and a power saving module coupled to the latch unit for raising a source voltage of the latch unit in response to a control signal on the word line, thereby reducing a leakage current for the latch unit.

Abstract: A plurality of fuse cells are arranged in an array. One or more fuse cells include a pair of fuse devices to output a pair of voltages, respectively, wherein the pair of fuse devices are redundantly programmed. A sense amplifier is coupled to the plurality of fuse cells to read the pair of voltage outputs from each of the plurality of fuse cells, respectively. A comparator circuit is coupled to the sense amplifier to compare the pair of voltage outputs for each of the plurality of fuse cells and to output the compared result.

Abstract: A method and structure for passing a bitline voltage regardless of its voltage level via a bitline in a memory device is disclosed. In one embodiment, the method includes detecting the bitline voltage of the bitline, feeding a control signal at an activation voltage level to the bitline pass device to maintain a pass voltage differential of the bitline pass device when the bitline is selected and passing the bitline voltage via the bitline pass device in response to the control signal, where the pass voltage differential is greater than a threshold voltage of the bitline pass device regardless of a level of the bitline voltage.

Abstract: A nonvolatile semiconductor memory device comprises a memory cell array including first and second mutually crossing lines and electrically erasable programmable memory cells arranged at intersections of the first and second lines, each memory cell containing a variable resistive element; a data write circuit operative to apply a voltage required for data write to the memory cell via the first and second lines; and a current limit circuit operative to limit the value of current flowing in the memory cell on the data write at a certain current limit value.

Abstract: Systems, devices and methods are disclosed, such as a system and method of sensing the voltage on bit lines that, when respective memory cells coupled to the bit lines are being read that compensates for variations in the lengths of the bit lines between the memory cells being read and respective bit line sensing circuits. The system and method may determine the length of the bit lines between the memory cells and the sensing circuits based on a memory address, such as a block address. The system and method then uses the determined length to adjust either a precharge voltage applied to the bit lines or the duration during which the bit lines are discharged by respective memory cells before respective voltages on the bit lines are latched.

Abstract: An integrated circuit device (e.g., a logic device or a memory device) having a memory cell array including a plurality of bit lines (e.g., first and second bit lines) and a plurality of bit line segments (e.g., first and second bit line segments) wherein each bit line segment is selectively and responsively coupled to or decoupled from its associated bit line via an associated isolation circuit. The memory cell array further includes a plurality of memory cells, wherein each memory cell includes a transistor having a first region, a second region, a body region, and a gate coupled to an associated word line via an associated word line segment. A first group of memory cells is coupled to the first bit line via the first bit line segment and a second group of memory cells is coupled to the second bit line via the second bit line segment.

Abstract: A magnetic storage device includes a plurality of MRAM memory cells connected to a data transfer line, a clamp transistor connected between the data transfer line and a reading signal line and configured to fixedly hold the potential of the data transfer line, and a reading circuit which is connected to the reading signal line and which reads the storage information of the memory cell. The reading circuit includes a hold switch connected between the reading signal line and a reading node N and configured to hold the potential of the node N, a capacitor connected between the node N and a ground end, a precharging switch connected between the node N and a power source and configured to charge the capacitor, and an inverter to which the potential of the node N is input to generate a digital signal.

Abstract: The circuit arrangement comprises a symmetrically constructed comparator (3), a non-volatile memory cell (10) and a reference element (20). The comparator (3) exhibits a latching function, and is connected in a differential current path that joins the power supply terminal (9) to a reference potential terminal (8). The non-volatile memory cell (10) is connected in a first branch (35) of the differential current path, and the reference element (20) is connected in a second branch (55) of the differential current path.

Abstract: A memory devices provide signals indicating when refresh operations are complete. The signals from a number of memory devices can be combined, such as by Oring, to provide a refresh complete signal to a power management controller. Dynamic factors can affect the refresh operation and the memory may be refreshed without restoring the entire system to a high power state. The time required to perform a refresh operation can be determined dynamically, allowing the system to be returned to a low power state as soon as refresh is complete. Ambient temperatures can be monitored to dynamically determine when to perform a refresh operation.

Abstract: Provided is a nonvolatile semiconductor memory device which reads out a memory cell at high speed. A minute current source (105) is connected to a clamp NMOS transistor (103) for clamping a drain voltage of a memory cell (101), and a minute current is caused to flow through the clamp NMOS transistor (103). When the current does not flow through the memory cell (101), by causing the minute current to flow through the clamp NMOS transistor (103), the drain voltage of the memory cell (101) is prevented from rising. A bias voltage (BIAS) to be input to the clamp NMOS transistor (103) can be set high and the drain voltage of the memory cell (101) can also be high, and hence a current value of the memory cell (101) becomes larger and speed of sensing a current of a sense amplifier circuit (104) is improved.