JP2013069368A - Semiconductor integrated circuit including non-volatile resistance change element and operation method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an integrated circuit capable of changing the state of a non-volatile resistance change element which varies output values, without stopping output operation.SOLUTION: An integrated circuit (50) includes a circuit comprising a non-volatile resistance change element which has a write terminal (11) for changing resistance of a non-volatile resistance change element (10) and a readout terminal (12) for reading out the resistance separately, and which can simultaneously perform writing operation and read-out operation by using the write terminal and the readout terminal which are not electrically coupled with each other. The circuit has at least an output terminal (22) for outputting output values according to the resistance value of the non-volatile resistance change element, and an input terminal (11) for changing the resistance value. The circuit can feed back a part of output from the output terminal to the input terminal.

Description

  The present invention relates to a semiconductor integrated circuit including a nonvolatile resistance change element and an operation method thereof.

  As the circuit integration scale increases due to the development of manufacturing technology, an increase in standby power is a problem. Various methods such as clock gating to stop the clock of the circuit during standby are adopted, but in order to eliminate standby leaks fundamentally, the power is turned off when the integrated circuit is not used, and the power is turned on when necessary. It is most desirable to immediately enter the operating state after turning on.

  In such a problem, when a volatile element such as DRAM or SRAM is used to hold the setting data, the setting data is temporarily saved in the memory when the power is turned off and then turned off. When switching from to on, data must be loaded from memory. In order to suppress such dead time before and after the start-up, the time for saving and loading data can be shortened by placing non-volatile elements in the vicinity of the operation circuit or in the operation circuit to keep the data in place. can do.

  Hereinafter, an oscillation frequency variable circuit will be described as an example. The oscillation frequency variable circuit is used not only for adjusting the processing speed of the integrated circuit as a clock generation source, but also by configuring a frequency lock circuit (FLO) by combining a reference frequency oscillator and a differential frequency detector, asynchronous serial communication, etc. It is also used for timing adjustment. FIG. 4 shows a conventional RC oscillation circuit (oscillation frequency variable circuit) (conventional circuit 1, Patent Document 1) in which a nonvolatile memory is installed outside.

  On the other hand, a load-free nonvolatile frequency variable circuit as shown in FIG. 5 can be obtained by replacing a resistor on the bias line loaded in the oscillation frequency variable circuit or in the oscillation frequency variable circuit with a nonvolatile resistance change element. Has been proposed (conventional circuit 2, patent document 2).

  Patent Document 3 discloses a semiconductor device that compares the resistance value of a nonvolatile variable resistance element with the potential or current of a node in the semiconductor device and changes the resistance value based on the result.

Japanese Patent Laid-Open No. 10-229326 WO2008 / 081742 Publication WO2008 / 102583 Publication

  In the conventional circuit 2, the writing operation for changing the resistance and the reading operation for reading the changed resistance (corresponding to the oscillation operation in this circuit) cannot be performed simultaneously. For this reason, even if a circuit for detecting a difference from the reference frequency and a feedback circuit for returning the information to the oscillation circuit are added, continuous operation (for example, frequency lock) cannot be performed.

  In other words, analog circuits including non-volatile variable resistance elements that have been proposed so far can start up quickly when the power is turned on / off, but even if feedback for the output signal is received, the operation must be stopped once. There is a problem that the output value cannot be changed. Even when the output value can be changed without stopping the output, there is a problem that noise is added to the output due to the write operation that changes the resistance. In the semiconductor device disclosed in Patent Document 3, the resistance read terminal and the write terminal are electrically coupled, and the voltage for writing and reading may have an electrical influence on other terminals. .

  In the first aspect, the (semiconductor) integrated circuit according to the present invention has a writing terminal for changing the resistance of the nonvolatile variable resistance element and a reading terminal for reading the resistance separately, and is electrically And a circuit having a nonvolatile resistance change element that can simultaneously perform a write operation and a read operation using the write terminal and the read terminal that are not coupled to each other. The circuit has at least an output terminal that outputs an output value corresponding to the resistance value of the nonvolatile variable resistance element, and an input terminal that changes the resistance value. A part of the output from the output terminal can be fed back to the input terminal.

  In a second aspect, the (semiconductor integrated) circuit operating method according to the present invention has a writing terminal for changing the resistance of the nonvolatile variable resistance element and a terminal for reading the resistance separately, and is electrically coupled. An output terminal for outputting an output value corresponding to a resistance value of the nonvolatile resistance change element, including a nonvolatile resistance change element capable of simultaneously performing a write operation and a read operation using the write terminal and the read terminal which are not ringed; The present invention relates to a method for operating a circuit having at least an input terminal for changing the resistance value. This method includes the step of feeding back a part of the output from the output terminal to the input terminal.

  With the configuration according to the first aspect, it is possible to provide an integrated circuit that can change the state of the nonvolatile variable resistance element that changes the output value without stopping the output operation. In addition, since the writing terminal and the reading terminal are independent, there is little electrical influence on each other.

  Further, the state of the nonvolatile variable resistance element that changes the output value can be changed without stopping the output operation by the method according to the second aspect.

It is a circuit schematic diagram concerning one example of the present invention. FIG. 2 is a circuit schematic diagram of an RC oscillation circuit that further embodies the configuration of FIG. 1. It is a circuit schematic diagram concerning the other Example of this invention. It is a circuit schematic diagram of the RC oscillation circuit of a prior art. It is a non-volatile frequency variable circuit of a prior art. It is an example of a structure of the non-volatile variable resistance element used for this invention.

  The integrated circuit according to the present invention stops the output by using a nonvolatile resistance change element having a writing terminal for changing the resistance and a terminal for reading the resistance separately (that is, the writing operation and the reading operation can be performed simultaneously). The resistance value of the nonvolatile variable resistance element can be rewritten so that the output value changes without any change. Therefore, a part of the output value can be fed back and returned to the input terminal that changes the resistance value of the nonvolatile resistance change element at any time. Therefore, for example, a set value of a circuit such as a frequency lock circuit in which an oscillator and an integrator continuously input and output each other can be made nonvolatile.

  When the resistance of the circuit whose output is controlled by the resistance value is changed to a nonvolatile resistance element, it is not necessary to load data as compared with the case where the resistance is changed via the gate of the transistor. In addition, since the state changes from time to time due to feedback, the power can be turned off asynchronously. For this reason, even when the power is turned off due to an unexpected situation, it is possible to maintain the state immediately before the power is turned off.

  The nonvolatile variable resistance element having a writing terminal for changing the resistance and a terminal for reading the resistance separately may have a three-terminal structure such as a flash memory. However, a voltage application condition for changing the resistance of the element (a high voltage is applied to the gate) and a voltage application condition when the element is used as an appropriate resistor (source-drain resistance) are greatly different. For this reason, when writing and reading are performed simultaneously, the operation range becomes extremely narrow. From this point, a nonvolatile magnetoresistive change element using magnetism in which the write terminal and the resistance read terminal are electrically separated is desirable. In this case, the voltage condition for changing the resistance and the voltage condition for use as a resistor can be optimized separately.

  It is more preferable to use a non-volatile magnetoresistive element that does not affect the read operation of the current generated by the write operation and the magnetic field generated thereby. This nonvolatile resistance change element can be realized by combining a magnetic body that can change the magnetization state with a current and a resistance body that changes its resistance by detecting a magnetic field in a specific direction A.

Noise generated by operating current when changing the resistance value by arranging the resistor and the magnetic body so that the direction of the magnetic field generated by the current passed to change the magnetization state of the magnetic body is perpendicular to A Can increase tolerance. Non-volatile magnetoresistive elements have a very large number of rewrites of 10 ⁸ or more. Therefore, it can also be used for a feedback circuit that constantly rewrites the set conditions.

  To summarize some of the embodiments according to the present invention, in the first aspect, the nonvolatile resistance change element detects a magnetic body capable of changing a magnetization state by a current and a magnetic field in a specific direction. Current-induced domain wall motion type resistance change element that combines resistors whose resistance changes, and the direction of the magnetic field generated by the current for changing the magnetization state of the magnetic body is the specific direction of the magnetic field detected by the resistor It is preferable that the variable resistance element is configured to be orthogonal.

  Thereby, the current generated by the write operation and the magnetic field generated by the current hardly affect the read operation. Therefore, a circuit with higher reliability can be formed. That is, it is possible to suppress noise from being applied to the output by the write operation that changes the resistance.

  The nonvolatile resistance change element is made of a ferromagnetic material having perpendicular magnetic anisotropy, and includes a first magnetization fixed region, a second magnetization fixed region, the first magnetization fixed region, and the second magnetization fixed. A first magnetization free layer including a magnetization free region connected to the region; a nonmagnetic layer provided in the vicinity of the first magnetization free layer; and a ferromagnetic material provided on the nonmagnetic layer. A reference layer, a first magnetization fixed layer group provided in the vicinity of the first magnetization fixed region, and between the first magnetization fixed layer group and the first magnetization fixed region, or the first magnetization fixed layer group It is preferable that the first barrier layer provided between the first barrier layer and the first barrier layer.

  It is preferable that the circuit further includes a circuit that adjusts (before feedback) an output amount from the output terminal that is fed back to the input terminal.

  The circuit having the nonvolatile resistance change element may include a second input terminal for inputting a signal in addition to the input terminal for feeding back a part of the output from the output terminal.

  The output from the output terminal is a signal whose frequency changes depending on the resistance value of the nonvolatile resistance change element, or a voltage value or a current value whose magnitude changes depending on the resistance value of the nonvolatile resistance change element. Is preferred.

  Moreover, it is preferable to have a plurality of the nonvolatile resistance change elements.

  The integrated circuit is preferably an oscillation frequency variable circuit or a frequency lock circuit.

  In a second aspect, it is preferable to include a step of adjusting (before feedback) an output amount from the output terminal that is fed back to the input terminal.

  The output from the output terminal is a signal whose frequency changes depending on the resistance value of the nonvolatile resistance change element, or a voltage value or a current value whose magnitude changes depending on the resistance value of the nonvolatile resistance change element. Is preferred.

Example 1
FIG. 1 shows a schematic circuit diagram according to one embodiment of the present invention. The integrated circuit having the feedback circuit 15 includes a circuit 17 including a nonvolatile resistance change element that can simultaneously perform a writing operation and a reading operation. The output of the circuit 17 including the nonvolatile resistance change element has a value corresponding to the resistance value of the nonvolatile resistance change element, and a part of the output is fed back to the input terminal that changes the resistance value. .

  FIG. 2 shows a more specific example of FIG. FIG. 2 shows an integrated circuit (RC oscillation circuit) 50 including the nonvolatile resistance change element 10 capable of simultaneously performing a write operation and a read operation according to an embodiment of the present invention. The RC oscillation circuit 50 includes an inverter circuit 20, and the output from the output terminal 22 is adjusted by the counter circuit 5 and fed back to the input terminal 11 for changing the magnetization state of the nonvolatile resistance change element 10.

  The nonvolatile resistance change element 10 used in the circuit shown in FIG. 2 is a domain wall motion type resistance change element having a writing terminal 11 (11 ′) for changing resistance and a terminal 12 (12 ′) for reading resistance separately. It is preferable to use it. As can be seen from FIG. 2, the write terminal and the read terminal are not electrically coupled. The variable resistance element 10 includes a resistor 2 and a magnetic body 1. The resistance value of the resistor 2 is changed by a magnetic field from a specific direction A. The distance and position between the resistor 2 and the magnetic body 1 may be in a range where the magnetic field A from the magnetic body 1 reaches the resistor 2. Therefore, a plurality of resistors 2 may be used for one magnetic body 1, and a plurality of resistance values may be used for a feedback circuit to increase the resistance value reading accuracy.

  In addition, WO2011 / 052475 (basic application: Japanese Patent Application No. 2009-245947), which is a related technology, illustrates a nonvolatile resistance change element having a writing terminal for changing resistance and a terminal for reading resistance separately. Has been. The nonvolatile resistance change element 10 preferably has such a structure as shown in FIG. 6, for example. The structure of the nonvolatile variable resistance element shown in FIG. 6 will be described below.

  As shown in FIG. 6A, the nonvolatile variable resistance element is made of a ferromagnetic material having perpendicular magnetic anisotropy, and includes a first magnetization fixed region 60a, a second magnetization fixed region 60c, and a first magnetization fixed region 60c. A first magnetization free layer 60 including a magnetization fixed region and a magnetization free region 60b connected to the second magnetization fixed region, a nonmagnetic layer 66 provided in the vicinity of the first magnetization free layer 60, and a ferromagnetic material. A reference layer 67 configured on the nonmagnetic 66 layer, a first magnetization fixed layer group 62 provided in the vicinity of the first magnetization fixed region 60a, a first magnetization fixed layer group 62, and a first magnetization fixed layer. A first blocking layer 61 provided between the region 60a and the first magnetization fixed layer group.

  Furthermore, a contact layer 64 and a second magnetization free layer 65 provided between the second magnetization fixed region 60 c and the nonmagnetic layer 66 are provided. Further, the second magnetization fixed layer group 63 is provided on the opposite side of the contact layer 64 across the first magnetization free layer 60.

  In FIG. 6B, the magnetization state of each layer in the “0” state is indicated by an arrow, and in FIG. 6C, the magnetization state in the “1” state is indicated by an arrow. The magnetizations of the first magnetization fixed region 60a, the second magnetization fixed region 60c, and the reference layer 67 are depicted as being fixed in the positive direction of the z axis, the negative direction, and the positive direction of the x axis, respectively. There is arbitraryness between. Since this optionality is obvious, it is omitted.

  Now, in the “0” state in which the magnetization free region 60b is magnetized upward as shown in FIG. 6B, the magnetization of the second magnetization free layer 65 is a leakage caused by the magnetization of the magnetization free region 60b in the upward direction. It faces in the positive x-axis direction by the magnetic flux. This is because the second magnetization free layer 65 is arranged above the magnetization free region 60b (in the positive z-axis direction), and the center of gravity of the second magnetization free layer 65 is in the positive x-axis direction with respect to the magnetization free region 60b. This is because they are shifted. As a result, the magnetizations of the second magnetization free layer 65 and the reference layer 67 become parallel, and this magnetic tunnel junction (MTJ) is in a low resistance state. DW indicates a domain wall.

  On the other hand, in the “1” state in which the magnetization free region 60b is magnetized downward as shown in FIG. 6C, the magnetization of the second magnetization free layer 65 leaks due to the magnetization of the magnetization free region 60b in the downward direction. It turns to the x-axis negative direction by magnetic flux. As a result, the magnetizations of the second magnetization free layer 65 and the reference layer 67 become antiparallel, and this MTJ is in a high resistance state. Thus, the information stored as the magnetization in the perpendicular direction of the magnetization free region 60b is transmitted to the magnetization of the second magnetization free layer 65 having the in-plane magnetization, and can be read out by the MTJ composed of the in-plane magnetization.

  In general, a high magnetoresistive effect ratio (MR ratio) can be obtained in an MTJ configured by in-plane magnetization. As a result, a large read signal can be obtained. The second magnetization free layer 65 and the reference layer 67 are made of a material having in-plane magnetic anisotropy. Specifically, Co—Fe—B and the like are exemplified. The nonmagnetic layer 66 is preferably composed of a nonmagnetic material. Specifically, Mg-O etc. are illustrated.

  Returning to FIG. 2, in order to reduce the influence of the write operation that changes the resistance of the resistor 2, it is generated by a write current (current) that is passed to change the magnetization state of the magnetic body 1 (magnetization state is upward). It is more desirable to arrange the resistor 2 and the magnetic body 1 so that the direction of the magnetic field is perpendicular to A. By arranging in this way, even if a pulsed current is applied to change the magnetization state of the magnetic body 1, it is difficult for the read current of the resistor 2 to receive noise from coupling of capacitance and inductance.

  The magnetization state of the magnetic body 1 varies depending on the direction in which the lower two terminals flow and the amount of current. The magnetization state of the magnetic body 1 does not change at the same time in the entire magnetic body, but forms a magnetic domain, and the magnetic domain state changes continuously by a write operation. For this reason, the resistance value of the resistor 2 whose resistance is changed by the magnetic field from the magnetic body 1 can be set with a finer analog precision with a value between them instead of a binary value, and can also be used for a feedback type analog circuit.

  The magnetization state of the magnetic body 1 and the resistance value of the resistor 2 are maintained even after the power is turned off. Therefore, when the circuit is newly operated, an output value reflecting the stored resistance value can be quickly obtained without loading data from an external memory. A part of the output value reflected in the resistance value of the resistor 2 is returned to the input terminal of the circuit through the feedback circuit. The resistance value of the nonvolatile variable resistance element 10 changes again by a signal input from the input terminal.

  Since the nonvolatile variable resistance element 10 has a writing terminal for changing resistance and a terminal for reading out the resistance separately, there is no operation to change the connection to the nonvolatile variable resistance element 10 in the circuit, and the output is stopped. It does not have to be. In addition, since the state is constantly rewritten, even if the power is turned off unexpectedly, it is possible to immediately recover the state before the power failure.

  The form of the output reflecting the resistance value is not particularly limited, and may be the absolute value of the voltage and current, or the frequency component. The output and feedback to the output need not be performed at any time. When the output reaches a desired value, the output and feedback to the output may be stopped. The form of the feedback circuit that returns a part of the output to the input is not particularly limited, and may include analog-digital conversion.

  In this embodiment, the resistor 2 is connected to an input terminal 21 and an output terminal 22 of an inverter circuit 20 in which an odd number of multiple stages of inverters 3 are connected in series. One terminal of the capacitance 4 is connected to the input terminal or output terminal of the inverter circuit 20. Further one side of the capacitance 4 is dropped to the ground potential. When the output side of the inverter circuit 20 becomes high (the input side is low because of an odd number of stages), the time until the input side is changed from low to high is governed by the time required to charge the capacitance 4 connected in parallel. The charging time becomes longer when the resistance of the resistor 2 is increased because the flowing current is decreased, and conversely, the charging time is shortened when the resistance is increased. When the output side of the inverter circuit 20 is low (the input side is high because of an odd number of stages), the discharge time until the input side is changed from high to low also varies depending on the resistance value. Thus, a circuit in which the inverter circuit 20 and the resistor 2 are connected in series and in a ring shape functions as an oscillator, and the oscillation frequency changes by changing the resistance of the resistor 2.

  The oscillation output destination is input to the counter circuit 5, and the write current value (current) to the magnetic body 1 is changed according to the counter value. The magnetization state of the magnetic body 1 changes due to the change in the write current value, the magnetic field from the magnetic body 1 in the resistor 2 changes, and the resistance changes due to the magnetoresistive effect of the resistor 2. Through this series of operations, feedback is always applied to the output terminal 51 of the RC oscillation circuit 50.

  Since it is not necessary to switch the input / output terminal of the resistor 2 for writing, the oscillation frequency can be changed without stopping the oscillation. In addition, the influence of current and magnetic field on the output terminal due to writing is small, and noise coming from the coupling of inductance is difficult to enter. Since the noise to the input temporarily changes the oscillation frequency of the output, the noise to the input further increases through the feedback circuit. Therefore, by suppressing input / output noise, unnecessary oscillation can be suppressed and the entire circuit can be stabilized quickly.

  When the counter value is compared with a frequency counter of an oscillator having a reference frequency, these circuits can function as a frequency lock circuit. Further, the resistance of the resistor 2 is non-volatile like the magnetic body 1. For this reason, it is possible to oscillate from the same frequency as before turning off the power even after turning off the power and starting up again. Accordingly, when the oscillation circuit is not used, the power can be turned off frequently, so that standby power can be suppressed.

(Example 2)
In the RC oscillation circuit 50 shown in FIG. 2, a circuit including a nonvolatile resistance change element (a portion excluding the counter circuit 5 and its output terminal 51) is an oscillation circuit and an active element that can output an output value by itself. However, for example, the circuit 17 including the nonvolatile resistance change element illustrated in FIG. 1 may be a passive circuit such as an RC filter including a nonvolatile resistance change element and a capacitance. That is, the signal source itself does not need to be included in the circuit 17. Therefore, the number of input terminals of the circuit 17 is not necessarily limited to one as shown in FIG. 1, and a second input terminal for inputting a signal in addition to the output from the feedback circuit 15 may be provided. For example, as shown in FIG. 3, the output from the receiving circuit 19 is input to the second input terminal of the RC filter circuit 17 (input 2), and is output to the feedback circuit 15 through the filter function of the circuit 17. A part of the signal may be fed back and input from the first input terminal of the circuit 17 (input 1).

(Example 3)
The nonvolatile resistance change elements 10 configured and arranged as shown in FIG. 2 are further arranged in an array and used as memory cells (not shown). By simultaneously monitoring the resistance of the resistor 2 when writing the state to the magnetic body 1, it is possible to check on-time whether or not the data to be written is actually written to the magnetic body 1 (verify operation). The read current of the resistor 2 is less likely to receive noise due to the coupling of capacitance and inductance. Therefore, accurate verification is possible because there is no mistake in reading the resistance monitor value.

  In addition, it is possible to reduce useless writing time by adding a circuit for stopping the writing operation after confirming the normal writing operation. Accordingly, it is possible to speed up the writing process for the entire memory cell including the verify operation. In addition, since the unnecessary writing time is reduced, the load on the cell due to the writing operation can be minimized, so that the reliability of the cell is improved.

  The present invention has been described with reference to the above-described embodiment. However, within the scope of the entire disclosure (including claims and drawings) of the present invention, examples and examples are further based on the basic technical concept. Can be changed and adjusted. Various combinations and selections of various disclosed elements are possible within the scope of the claims of the present invention. That is, the present invention naturally includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the drawings, and the technical idea.

DESCRIPTION OF SYMBOLS 1 Magnetic body 2 Resistor 3 Inverter 4 Capacitance 5 Counter circuit 10 Non-volatile resistance change element 11 Input terminal 15 Feedback circuit 17 Circuit containing a non-volatile resistance change element 19 Reception circuit 20 Inverter circuit 50 RC oscillation circuit 51 Output terminal 60 1st Magnetization free layer 60a first magnetization fixed region 60b magnetization free region 60c second magnetization fixed region 61 first blocking layer 62 first magnetization fixed layer group 63 second magnetization fixed layer group 64 contact layer 65 second magnetization free layer 66 nonmagnetic Layer 67 Reference layer

Claims (10)

  A write terminal for changing the resistance of the nonvolatile variable resistance element and a read terminal for reading the resistance are separately provided, and writing is performed using the write terminal and the read terminal which are not electrically coupled. Including a circuit having a nonvolatile resistance change element capable of simultaneously performing an operation and a read operation, wherein the circuit has an output terminal for outputting an output value corresponding to the resistance value of the nonvolatile resistance change element, and an input for changing the resistance value An integrated circuit comprising: at least a terminal; and a part of an output from the output terminal can be fed back to the input terminal.   The nonvolatile resistance change element is a current-induced domain wall motion type resistance change element that combines a magnetic body that can change a magnetization state with a current and a resistance body that changes its resistance by detecting a magnetic field in a specific direction. 2. The variable resistance element according to claim 1, wherein a direction of a magnetic field generated by a current for changing a magnetization state of the magnetic body is orthogonal to a specific direction of the magnetic field detected by the resistor. An integrated circuit as described. The nonvolatile variable resistance element is
A ferromagnetic body having perpendicular magnetic anisotropy, and a first magnetization fixed region, a second magnetization fixed region, a first magnetization fixed region and a magnetization free region connected to the second magnetization fixed region; A first magnetization free layer comprising:
A nonmagnetic layer provided in the vicinity of the first magnetization free layer;
A reference layer made of a ferromagnetic material and provided on the nonmagnetic layer;
A first magnetization fixed layer group provided in the vicinity of the first magnetization fixed region;
The first blocking layer provided between the first magnetization pinned layer group and the first magnetization pinned region or sandwiched between the first magnetization pinned layer groups. 3. The integrated circuit according to 2.   The integrated circuit according to claim 1, further comprising a circuit that adjusts an output amount from the output terminal to be fed back to the input terminal.   The circuit having the nonvolatile resistance change element includes a second input terminal for inputting a signal in addition to the input terminal for feeding back a part of the output from the output terminal. The integrated circuit as described in any one of -4.   The output from the output terminal is a signal whose frequency changes depending on the resistance value of the nonvolatile resistance change element, or a voltage value or a current value whose magnitude changes depending on the resistance value of the nonvolatile resistance change element. An integrated circuit according to any one of claims 1 to 5.   The integrated circuit according to claim 1, comprising a plurality of the nonvolatile resistance change elements.   The integrated circuit according to claim 1, wherein the integrated circuit is an oscillation frequency variable circuit or a frequency lock circuit. A writing terminal for changing the resistance of the nonvolatile variable resistance element and a terminal for reading the resistance are separately provided, and a writing operation and a reading operation are performed using the writing terminal and the reading terminal which are not electrically coupled. An operation method of a circuit including at least a nonvolatile resistance change element that can be performed simultaneously, an output terminal that outputs an output value corresponding to a resistance value of the nonvolatile resistance change element, and an input terminal that changes the resistance value,
A method for operating a circuit, comprising a step of feeding back a part of an output from an output terminal to the input terminal.   The operation method according to claim 9, further comprising a step of adjusting an output amount from the output terminal to be fed back to the input terminal.

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