CN102122525B - Readout amplifying circuit for resistive random access memory (RRAM) cell - Google Patents

Abstract

The invention discloses a readout amplifying circuit for a resistive random access memory (RRAM) cell, and provides a novel readout amplifying circuit for an RRAM cell, which reduces the influence of interference current on reading operation, lowers the overall direct current (DC) power consumption and improves the accuracy of a reference voltage generating circuit. The readout amplifying circuit consists of a comparative readout level and the reference voltage generating circuit, wherein, the comparative readout level consists of N sense bits, the N sense bits and bit lines of an RRAM cell array are in a relationship of one-to-one correspondence, and each sense bit consists of a sensitive amplifier, a feedback resistor and a voltage comparator; and the reference voltage generating circuit consists of M voltage division elements and an operational amplifier, the voltage division elements in the reference voltage generating circuit are capacitors which are connected in series, and a positive input terminal of the operational amplifier is connected with a voltage division point. By utilizing the readout amplifying circuit, the misread rate can be lowered, the overall DC power consumption can be reduced, and the reference voltage output precision of the reference voltage generating circuit can be improved.

Description

Amplifying circuit is read in a kind of resistance-change memory unit

Technical field

The present invention relates to the amplifying circuit of reading of resistance-change memory cell array periphery, integrated circuit (IC) design field, be specifically related to a kind ofly change the change in resistance of sampling with DC current gain, produce the amplifying circuit of reading of reference voltage with the controlled capacitance voltage divider.

Background technology

Nonvolatile memory is a kind ofly can still preserve the storer of original storage information after power down, has obtained using widely in contemporary electronic systems.Nonvolatile memory is of a great variety, and (Resistive Random Access Memory RRAM) is wherein a kind of to resistance-variable storing device.Since resistance-variable storing device have superelevation storage density, simple in structure, speed is fast and non-volatile characteristics, application prospect is very wide.

The resistance-change memory cell array is the core of resistance-variable storing device, is made up of according to certain space structure a large amount of resistance-change memory unit.Interdigitated electrode design is a kind of typical resistance-change memory cell array structure, and its integrated level is higher, the microelectronic technique of compatible main flow.Interdigitated electrode design is the parallel nanowires of two-layer mutual square crossing, forms a grid.Form a resistance-change memory unit at each place, point of crossing, the resistance-change memory unit is with high-impedance state and low resistance state difference presentation logic " 0 " and " 1 ".Fig. 1 is interdigitated electrode design resistance-change memory cell array physical arrangement synoptic diagram.The resistance-change memory unit is made up of top electrode, hearth electrode and the middle resistive material of inserting, and Fig. 2 is its cross sectional representation.Fig. 3 is that the voltage and current of resistance-change memory unit concerns synoptic diagram, and wherein dotted line is the I-V curve of high-impedance state storage unit, and solid line is the I-V curve of low resistance state storage unit.When the voltage at two ends, resistance-change memory unit met or exceeded high-impedance state conversion current potential A point voltage value, the resistance-change memory unit changed high-impedance state into, when the voltage at two ends, resistance-change memory unit meets or exceeds low resistance state conversion current potential B point voltage value, changed low resistance state into.The voltage at two ends, resistance-change memory unit between A point voltage value and B point voltage value the time resistance state do not change.Utilize this characteristic of resistance-change memory unit, thereby realize writing of information by the resistance state that the size that changes impressed voltage changes the resistance-change memory unit; When reading data, two electrodes apply and read voltage in the resistance-change memory unit, by detecting resistance-change memory unit resistance state, realize reading of information.In order to detect the resistance state of differentiating the resistance-change memory unit, the current signal that will flow through resistive resistance-change memory unit changes voltage signal into reads that to amplify be a kind of effective and efficient manner.

Fig. 4 is a kind of structure for amplifying, WL of typically reading ₁Be the first word line of resistance-change memory array, WL ₂Be the second word line of resistance-change memory array ..., WL _jBe the j word line of resistance-change memory array ..., WL _PBe the P word line of resistance-change memory array, BL ₁Be first bit line of resistance-change memory array, BL ₂Be second bit line of resistance-change memory array ..., BL _iBe the i bit line of resistance-change memory array ..., BL _NBe the N bit line of resistance-change memory array, N is the number of bit of resistance-change memory cell array, and P is the number of resistance-change memory array word line, and P and N are positive integer.This read structure for amplifying by relatively read level, generating circuit from reference voltage two parts form.Wherein relatively read level and be made up of the individual position of reading of N, N bit line of corresponding resistance-change memory cell array namely first read corresponding first bit line in position respectively, and second reads corresponding second bit line in position, by that analogy.Each is read the position and forms by pull-up resistor, voltage comparator, first bit line and first that first end of reading the pull-up resistor of position connects the resistance-change memory cell array is read the positive input of the sense amplifier of position, other end ground connection, first inverting input of reading the sense amplifier in the position connects the output terminal V of generating circuit from reference voltage _Ref, first reads the output V of position _Out1Be connected to outside output; Second reads the position reads in the position connected mode and first of pull-up resistor and sense amplifier to N and reads similar, be that each end of pull-up resistor of reading the position is read a corresponding bit lines with this and linked to each other with this positive input of reading the sense amplifier in the position, other end ground connection, each inverting input of reading the sense amplifier of position connects the output terminal V of generating circuit from reference voltage _Ref, each reads the outside output of output termination of position.Generating circuit from reference voltage is made up of M sectional pressure element and operational amplifier, M is positive integer, each sectional pressure element is resistance, M sectional pressure element adopts serial arrangement to connect, the joint portion of per two sectional pressure elements forms a dividing point, the current potential of dividing point can calculate, and according to the needs of circuit, selects suitable dividing point (representing with the A point among the figure).The positive input of operational amplifier connects a dividing point such as A point, the output terminal V of operational amplifier _RefLinking to each other with its inverting input forms a voltage follower, in order to improve driving force.The output terminal V of generating circuit from reference voltage _RefBe connected to and relatively read in the level inverting input that each reads the sense amplifier of position, in order to reference voltage to be provided.

This amplifying circuit of typically reading is to resistance-change memory unit rm ₀When carrying out read operation, at the first word line WL ₁On add and read voltage, the first bit line BL ₁Ground connection, first read the position voltage comparator with first read the position pull-up resistor on dividing potential drop and the output voltage V of generating circuit from reference voltage _RefRelatively, the dividing potential drop on pull-up resistor is greater than V _RefThe time, amplify generation binary output signal 1, i.e. a V _Out1Be 1, the dividing potential drop on pull-up resistor is less than V _RefThe time, amplify generation binary output signal 0, i.e. a V _Out1Be 0, thereby realize resistance-change memory unit rm ₀Reading of resistance state.The playback mode of other storage unit is identical therewith.Yet, for reading for the amplifying circuit of Fig. 4, have the deficiency of several aspects will have a strong impact on the performance of reading amplifying circuit:

1. can't eliminate the influence of the interference current that is produced by interdigitated electrode design shown in Figure 1, the increase of resistance-change memory cell array capacity is restricted.Because the electrology characteristic of resistance-change memory unit itself and the characteristic of interdigitated electrode design, make to adopt as Fig. 4 read amplifying circuit the time can't eliminate interference current between the bit line of resistance-change memory cell array, when the word line of resistance-change memory cell array and bit line quantity increase, interference current will increase thereupon, thereby the increase of resistance-change memory cell array capacity has been caused restriction.It specifically produces reason as shown in Figure 6, if rm ₀The unit is high-impedance state, rm ₁, rm ₂, rm ₃Three unit all are low resistance state, at the first word line WL ₁On add and read voltage, the first bit line BL ₁Ground connection is read rm ₀During the value of unit, the path representation that dotted line the is indicated rm that flows through ₀Electric current, the path that solid line is indicated is sneak path, flow through sneak path for interference current.Along with the increase of resistance-change memory cell array capacity, the quantity of sneak path increases, and interference current will be tending towards seriously causing reading the resistance state that amplifying circuit can not correctly be identified the resistance-change memory unit gradually.

2. the dc power of reading amplifying circuit is bigger.Because each that relatively read level read working load resistance in the position as the element that detects resistance-change memory unit resistance state, thereby cause having DC channel from the word line of resistance-change memory cell array to the ground, when the bit line quantity of resistance-change memory cell array increases, cause the dc power of read operation to increase thereupon.Simultaneously, owing to use resistance as sectional pressure element in the generating circuit from reference voltage, cause input voltage V _InputThere is DC channel over the ground, produced bigger dc power.The dc power that above reason causes reading amplifying circuit integral body is bigger.

3. the accuracy of generating circuit from reference voltage is affected.The output voltage V of generating circuit from reference voltage _RefPrecision the matching precision of wherein sectional pressure element is had stronger dependence, in the preparation process of integrated circuit, resistance is difficult for realizing accurate coupling, owing to used resistance as sectional pressure element in the generating circuit from reference voltage, thus reduced the accuracy of generating circuit from reference voltage.

Because the existence of above shortcoming, need read amplifying circuit to original resistance-change memory unit is improved, with the influence of reduction by the interference current of the electrology characteristic generation of interdigitated electrode design and resistance-change memory unit itself, further reduce original dc power of reading amplifying circuit, improve the accuracy of generating circuit from reference voltage simultaneously.

Summary of the invention

The problem to be solved in the present invention is: provide a kind of novel resistance-change memory unit to read amplifying circuit, the interference current that reduction is brought by the electrology characteristic of interdigitated electrode design resistance-change memory cell array itself is to the influence of read operation, reduce the whole dc power of reading amplifying circuit, improve the accuracy of generating circuit from reference voltage.

Technical scheme of the present invention is:

Resistance-change memory of the present invention unit is read amplifying circuit and is also formed by relatively reading level and generating circuit from reference voltage.Relatively read level and read the position by N (N is the number of resistance-change memory cell array bit line) and forms, corresponding one by one with resistance-change memory cell array bit line respectively, namely i reads a corresponding i bit line BL _i, 1≤i≤N.Each is read the position and is made up of a sense amplifier, a feedback resistance, a voltage comparator.Read in the position positive input ground connection of sense amplifier, inverting input and i bit line BL at i _iLink to each other the output terminal V of sense amplifier _OiBe connected to the inverting input of this sense amplifier, the output terminal V of the inverting input of voltage comparator and sense amplifier by feedback resistance _OiLink to each other the output terminal V of the positive input of voltage comparator and generating circuit from reference voltage _RefLink to each other the output terminal V of voltage comparator _OutiThe output terminal of reading the position as i is connected to outside output.

Generating circuit from reference voltage is made up of M (M is positive integer) sectional pressure element and an operational amplifier, and each sectional pressure element is electric capacity.M sectional pressure element contacted in the following manner: the input end IN of first sectional pressure element ₁Ground connection, the output terminal OUT of first sectional pressure element ₁Be connected to the input end IN of second sectional pressure element ₂, the output terminal OUT of second sectional pressure element ₂Be connected to the input end IN of the 3rd sectional pressure element ₃, by that analogy, k (the output terminal OUT of sectional pressure element of 1≤k≤M-1) _kBe connected to the input end IN of k+1 sectional pressure element _K+1, the output terminal of M sectional pressure element and reference voltage source V _InputLink to each other.Output terminal OUT at first sectional pressure element ₁Input end IN with second sectional pressure element ₂The junction surface produces first dividing point, by that analogy, and at the output terminal OUT of k sectional pressure element _kInput end IN with the k+1 sectional pressure element _K+1Produce the k dividing point, namely produce a dividing point at the junction surface of per two sectional pressure elements.These sectional pressure elements are to the voltage V of reference voltage source _InputCarry out dividing potential drop, the current potential V of k dividing point _kSatisfy:

$V_k=\left(\frac{k}{M}\right)\·V_{\mathrm{input}}$ Formula one

When being arranged in high-impedance state, reads note resistance-change memory unit position sense amplifier output terminal V _OiCorresponding voltage value is V _H, read position sense amplifier output terminal V when the resistance-change memory unit is arranged in low resistance state _OiCorresponding voltage value is V _LFor given voltage resolving accuracy T, the voltage resolving accuracy refers to the minimum voltage that a sectional pressure element divides (V for example _InputDuring for 4V, adopt 4 sectional pressure elements can reach the voltage resolving accuracy of 1V), exist:

$M=\left(\frac{1}{T}\right)\·V_{\mathrm{input}}$ Formula two

For the voltage comparator that each is read in the position can be distinguished high-impedance state and the corresponding magnitude of voltage of low resistance state that this reads the resistance-change memory unit of sense amplifier sampling output in the position, the current potential V of the dividing point of choosing effectively _jShould satisfy:

$V_j=\frac{V_H+V_L}{2}$ Formula three

Got by formula one, formula two and formula three:

$j=\frac{V_H+V_l}{2T}$ Formula four

The positive input of the operational amplifier in the generating circuit from reference voltage links to each other with the j dividing point of choosing, the output terminal V of operational amplifier _RefBe connected to the inverting input of this operational amplifier, constitute a voltage follower, the output terminal V of operational amplifier _RefAs the output terminal of reference voltage generation circuit with relatively read in the level each and read that the positive input of voltage comparator links to each other in the position.

To resistance-change memory unit rm ₀And rm ₁Sampling process can represent R with the equivalent electrical circuit among Fig. 9 _QEquivalent resistance on the expression sneak path, SA ₁The sense amplifier of position, SA are read in expression first ₂The sense amplifier of position, V are read in expression second _I1Expression sense amplifier SA ₁The inverting input current potential, V _I2Expression sense amplifier SA ₂The inverting input current potential, I ₁SA during the expression read operation ₁Feedback resistance on electric current, I ₂SA during the expression read operation ₂Feedback resistance on electric current, I ₃Sneak path equivalent resistance R during the expression read operation _QOn electric current, I ₄Resistance-change memory unit rm flows through during the expression read operation ₀Electric current, I ₅Resistance-change memory unit rm flows through during the expression read operation ₁Electric current.

Read in the position at each, the feedback arrangement that sense amplifier and feedback resistance constitute has been realized the sampling to resistance-change memory unit resistance state, each voltage comparator of reading in the position compares the back amplification with signal and the reference voltage of sampling, and forms binary digital signal output.

Adopt the present invention can reach following technique effect:

1. use the resistance state of sense amplifier sampling resistance-change memory unit, utilize the characteristic of the input end zero current of sense amplifier, reduced the influence of the interference current between the bit line, thereby realized lower read false rate.

2. in the feature of relatively reading the zero input current that has utilized sense amplifier in the level, sectional pressure element has adopted electric capacity in the generating circuit from reference voltage simultaneously, has reduced the whole dc power of circuit.

3. because in the preparation technology of integrated circuit, the easier realization of capacity ratio resistance is mated accurately, sectional pressure element adopts electric capacity to improve the precision of generating circuit from reference voltage output reference voltage.

Description of drawings

Fig. 1 is the described typical interdigitated electrode design resistance-change memory cell array physical arrangement of background technology;

Fig. 2 is the cross sectional representation of interdigitated electrode design resistance-change memory shown in Figure 1 unit;

Fig. 3 is the I-V characteristic synoptic diagram of resistance-change memory unit in the interdigitated electrode design resistance-change memory cell array shown in Figure 1;

Fig. 4 is that amplification circuit structure figure is read in the described typical interdigitated electrode design resistance-change memory of background technology unit;

Fig. 5 is generating circuit from reference voltage structural drawing among Fig. 4;

Fig. 6 is that the interference current synoptic diagram in the amplification circuit structure is read in Fig. 4 interdigitated electrode design resistance-change memory unit;

Fig. 7 is that amplification circuit structure figure is read in resistance-change memory of the present invention unit;

Fig. 8 is generating circuit from reference voltage structural drawing among Fig. 7;

Fig. 9 is that the present invention relatively reads sense amplifier signal sampling process equivalent circuit diagram in the level.

Embodiment

Below in conjunction with accompanying drawing, describe structure and the course of work that amplifying circuit is read in resistance-change memory of the present invention unit in detail.

Fig. 7 is that amplification circuit structure figure is read in resistance-change memory of the present invention unit, the present invention by relatively read level, generating circuit from reference voltage forms.Relatively read level and formed by the individual position of reading of N, corresponding one by one with resistance-change memory cell array bit line respectively, namely first read the corresponding first bit line BL in position ₁, second reads the corresponding second bit line BL in position ₂, by that analogy, N reads the corresponding N bit line BL in position _NEach is read the position and is made up of a sense amplifier, a feedback resistance, a voltage comparator.Read in the position positive input ground connection of sense amplifier, inverting input and i bit line BL at i _iLink to each other the output terminal (V of sense amplifier _Oi) being connected to the inverting input of this sense amplifier by feedback resistance, the inverting input of voltage comparator links to each other with the output terminal of sense amplifier, the output terminal V of the positive input of voltage comparator and generating circuit from reference voltage _RefLink to each other the output terminal V of voltage comparator _OutiBe connected to outside output as first output terminal of reading the position.

Generating circuit from reference voltage is made up of M (M is positive integer) sectional pressure element and an operational amplifier among Fig. 8, and each sectional pressure element is made up of an electric capacity.M sectional pressure element contacted in the following manner: the input end IN of first sectional pressure element ₁Ground connection, the output terminal OUT of first sectional pressure element ₁Be connected to the input end IN of second sectional pressure element ₂, the output terminal OUT of second sectional pressure element ₂Be connected to the input end IN of the 3rd sectional pressure element ₃, by that analogy, k (the output terminal OUT of sectional pressure element of 1≤k≤M) _kBe connected to the input end IN of k+1 sectional pressure element _K+1, the output terminal of M sectional pressure element and reference voltage source V _InputLink to each other.Output terminal OUT at first sectional pressure element ₁Input end IN with second sectional pressure element ₂The junction surface produces first dividing point, by that analogy, and at k (the output terminal OUT of sectional pressure element of 1≤k≤M) _kInput end IN with the k+1 sectional pressure element _K+1Produce the k dividing point, namely produce a dividing point at the junction surface of per two sectional pressure elements.The current potential of j dividing point satisfies:

$V_j=\frac{V_H+V_L}{2},$

The number M of sectional pressure element satisfies:

$M=\left(\frac{1}{T}\right)\·V_{\mathrm{input}}$

The positive input of the operational amplifier in the generating circuit from reference voltage links to each other with the dividing point of choosing, the output terminal V of operational amplifier _RefBe connected to the inverting input of this operational amplifier, constitute a voltage follower, the output terminal V of operational amplifier _RefAs the output terminal of reference voltage generation circuit with relatively read in the level each and read that the positive input of voltage comparator links to each other in the position.

When carrying out read operation, apply in corresponding word lines and to read voltage, once read the data of the resistance-change memory unit on delegation's word line.The composition of reading the position owing to each is identical, remembers that each resistance of reading feedback resistance in the position is R _f, when the resistance-change memory unit on this word line was carried out read operation, each read the DC current gain of sense amplifier in the position by the ratio decision of feedback resistance and resistance-change memory cell resistance.To read the first word line WL ₁On the resistance-change memory unit be that example describes: at the first word line WL ₁On apply and read voltage V _r, the first bit line BL ₁Be connected note rm with the inverting input of sense amplifier ₀The resistance of unit is R _M0, to rm ₀When the unit carries out read operation, can be got by the closed loop characteristic of inverting amplifier, corresponding first reads the DC current gain of sense amplifier in the position by the ratio R of feedback resistance and resistance-change memory cell resistance _f/ R _M0Determine that the pass is between output and the input voltage:

$V_{o1}=-\frac{R_f}{R_{m0}}\·V_r$

When being in different resistance state, resistance-change memory unit rm ₀Have different resistances, thereby cause output voltage V _O1Difference with the sampling unit resistance changes, and the variation of the resistance of resistance-change memory unit is converted to the variation of the output voltage of sense amplifier, with the resistance of this resistance-change memory unit of sampling.V _O1Output and first read that the inverting input of voltage comparator links to each other in the position, voltage comparator compares the generation output signal by the output signal to reference voltage and sense amplifier.

Each is read in the position, and sense amplifier and feedback resistance have realized that this reads the position to the sampling function of resistance-change memory unit resistance.Following surface analysis is read the course of work of amplifying circuit, with to the first word line WL ₁On resistance-change memory unit rm ₀, rm ₁Sampling process be that example is analyzed explanation because R _QCan regard the equivalent resistance between any two storage unit bit lines as, again because the read operation principle is identical, so this analysis is equally applicable to any two the resistance-change memory unit on the same word line.To rm ₀, rm ₁The equivalent sampling circuit as shown in Figure 9: rm ₀, rm ₁An end and word line WL ₁Link to each other rm ₀The other end read sense amplifier SA in the position by first bit line and first ₁Inverting input link to each other SA ₁Output terminal V _O1Link to each other SA through feedback resistance with its inverting input ₁Positive input end grounding; Rm ₁The other end read sense amplifier SA in the position by second bit line and second ₁Inverting input link to each other SA ₁Output terminal V _O2Link to each other SA through feedback resistance with its inverting input ₁Positive input end grounding, the resistance R on all sneak paths _QCome equivalently represented.First reads the sense amplifier SA of position ₁And rm ₀, feedback resistance constituted an inverting amplifier; Second reads the sense amplifier SA of position ₂And rm ₁, feedback resistance constituted the another one inverting amplifier.Note rm ₀Resistance be R _M0, rm ₁Resistance be R _M1, each is read, and the resistance of feedback resistance equals constant R in the position _fDraw following equation according to Kirchhoff's law:

$\frac{V_r-V_{i1}}{R_{m0}}-I_1-I_3=0---\left(1\right)$

$\frac{V_r-V_{i2}}{{\mathrm{<figure-callout\; id="1"\; label="R\; m"\; filenames="HDA0000055368550000051.png"\; state="\{\{state\}\}">R</figure-callout>}}_m}+I_3-I_2=0---\left(2\right)$

$\frac{V_{i1}-V_{i2}}{R}=I_3---\left(3\right)$

$\frac{V_{i1}-V_{o2}}{R_f}{=I}_1---\left(4\right)$

$\frac{V_{i2}-V_{o2}}{R_f}=I_2---\left(5\right)$

$V_{o1}=a{\&CenterDot;V}_{i1}---\left(6\right)$

$V_{o2}=a{\&CenterDot;V}_{i2}---\left(7\right)$

Wherein a represents the open-loop gain of sense amplifier in the signal sampling amplifier stage, and the value of applying is V on the word line _rRead voltage, R represents sneak path equivalent resistance R between two bit lines _QResistance, I ₃Expression sneak path interference current.Can be got by above equation arrangement

$\frac{V_{o1}}{V_{o2}}=\frac{R_f\&CenterDot;(R_{m0}+{\mathrm{<figure-callout\; id="1"\; label="R\; m"\; filenames="HDA0000055368550000051.png"\; state="\{\{state\}\}">R</figure-callout>}}_m+R)+R{\&CenterDot;R}_{m1}(a-1)}{R_f\&CenterDot;(R_{m0}+{\mathrm{<figure-callout\; id="1"\; label="R\; m"\; filenames="HDA0000055368550000051.png"\; state="\{\{state\}\}">R</figure-callout>}}_m+R)+R{\&CenterDot;R}_{m0}(a-1)}---\left(8\right)$

Can be got by equation (8), when the open-loop gain a of sense amplifier is tending towards infinity (ideal situation), the influence of interference current can be ignored between the bit line, and the output voltage ratio only ratio with the high-impedance state resistance of resistance-change memory unit and low resistance state resistance is relevant, that is:

$\frac{V_{o1}}{V_{o2}}=\frac{R_{m1}}{R_{m0}}---\left(9\right)$

By formula (9), the ratio of output voltage depends on the ratio of high-impedance state resistance and the low resistance state resistance of resistance-change memory unit, and with sneak path on equivalent resistance R _QIrrelevant, thus show that this reads the influence that amplifying circuit can reduce interference current on the sneak path, the resistance state of the resistance-change memory unit of sampling effectively.

Sectional pressure element in the generating circuit from reference voltage has used electric capacity to carry out dividing potential drop, in the technology of integrated circuit, the easier realization of capacity ratio resistance is accurately mated, when temperature variation, the appearance value of electric capacity changes, but proportionate relationship each other still can keep necessarily, so the reference voltage that produces varies with temperature very little, and because electric capacity is inhibited to direct current signal, so the dc power of generating circuit from reference voltage can be down to 0 in theory.The input reference voltage V of generating circuit from reference voltage _InputCan be produced by general reference voltage generating circuit.

The reference voltage V of generating circuit from reference voltage output _RefBe connected to each and read voltage comparator in the position, realized reference voltage V by each voltage comparator of reading the position _RefCompare and enlarge with this voltage of reading sense amplifier sampling output of position, thereby the low amplitude of oscillation sampled voltage of resistance-change memory unit is amplified to the voltage that digital circuit can be identified, and then will read the result and output to external circuit.

Claims (1)

1. amplifying circuit is read in a resistance-change memory unit, and it is formed by relatively reading level and generating circuit from reference voltage, relatively reads level and is made up of the individual position of reading of N, and the individual position of reading of N is corresponding one by one with resistance-change memory cell array bit line, and namely i reads the corresponding i bit line BL in position _i, 1≤i≤N, N are the number of resistance-change memory cell array bit line; Generating circuit from reference voltage is made up of M sectional pressure element and an operational amplifier, and M is positive integer; It is characterized in that:

Described each of relatively reading in the level read the position and is made up of a sense amplifier, a feedback resistance, a voltage comparator; Read in the position positive input ground connection of sense amplifier, inverting input and i bit line BL at i _iLink to each other the output terminal V of sense amplifier _OiBe connected to the inverting input of this sense amplifier, the output terminal V of the inverting input of voltage comparator and sense amplifier by feedback resistance _OiLink to each other the output terminal V of the positive input of voltage comparator and generating circuit from reference voltage _RefLink to each other the output terminal V of voltage comparator _OutiThe output terminal of reading the position as i is connected to outside output;

Each sectional pressure element in the described generating circuit from reference voltage is electric capacity, and M sectional pressure element contacted in the following manner: the input end IN of first sectional pressure element ₁Ground connection, the output terminal OUT of k sectional pressure element _kBe connected to the input end IN of k+1 sectional pressure element _K+1, the output terminal of M sectional pressure element and reference voltage source V _InputLink to each other, 1≤k≤M-1 produces a dividing point at the junction surface of per two sectional pressure elements, namely at the output terminal OUT of k sectional pressure element _kInput end IN with the k+1 sectional pressure element _K+1Produce the k dividing point;

The positive input of the operational amplifier in the described generating circuit from reference voltage links to each other with the j dividing point, the output terminal V of operational amplifier _RefBe connected to the inverting input of this operational amplifier, constitute a voltage follower, the output terminal V of operational amplifier _RefRead with relatively reading in the level each that the positive input of voltage comparator links to each other in the position as the output terminal of reference voltage generation circuit, dividing point j satisfies in the generating circuit from reference voltage

$j=\frac{V_H+V_L}{2T}$

V _HRead position sense amplifier output terminal V when being arranged in high-impedance state for the resistance-change memory unit _OiCorresponding voltage value, V _LRead position sense amplifier output terminal V when being arranged in low resistance state for the resistance-change memory unit _OiCorresponding voltage value, T is the voltage resolving accuracy, the voltage resolving accuracy refers to the minimum voltage that a sectional pressure element divides;

The number M of sectional pressure element satisfies in the described generating circuit from reference voltage

$M=\left(\frac{1}{T}\right)\&CenterDot;V_{\mathrm{input}}$

V _InputBe the voltage of reference voltage source, T is the voltage resolving accuracy, and the voltage resolving accuracy refers to the minimum voltage that a sectional pressure element divides.

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