CN107342103A - A kind of magnetic RAM and its Magnetic memory cell reading method - Google Patents
A kind of magnetic RAM and its Magnetic memory cell reading method Download PDFInfo
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- CN107342103A CN107342103A CN201610283466.6A CN201610283466A CN107342103A CN 107342103 A CN107342103 A CN 107342103A CN 201610283466 A CN201610283466 A CN 201610283466A CN 107342103 A CN107342103 A CN 107342103A
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
- G11C11/165—Auxiliary circuits
- G11C11/1673—Reading or sensing circuits or methods
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
- G11C11/165—Auxiliary circuits
- G11C11/1675—Writing or programming circuits or methods
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- Computer Hardware Design (AREA)
- Mram Or Spin Memory Techniques (AREA)
Abstract
The present invention provides a kind of magnetic RAM, the array formed including multiple Magnetic memory units, magnetic RAM is also included from reference to read module, from the of-state voltage for being used to change into high-impedance state according to the MTJ of Magnetic memory unit with reference to read module, the logic state of reading Magnetic memory unit.The present invention also provides a kind of Magnetic memory cell reading method of magnetic RAM.Magnetic RAM and its Magnetic memory cell reading method provided by the invention, utilize the magneto-resistor bias-dependent of MTJ, the digital independent from reference is realized, solves the problems, such as that reading data causes read error rate high the standard deviation Spreading requirements harshness of reference resistance.
Description
Technical field
The present invention relates to the memory area of semiconductor chip, and in particular to a kind of magnetic RAM and its magnetic
Resistance memory cell reading method.
Background technology
Magnetic RAM (MRAM) is a kind of emerging non-volatile holographic storage technology.It possesses the reading of high speed
Writing rate and high integration, and can be repeatedly written by unlimited number of.
One magnetic RAM is made up of the Magnetic memory unit of array.Each Magnetic memory unit includes
One structure for being MTJ (MTJ).MTJ be by two layers of ferrimagnet clip one layer it is non-
Often thin non-ferric magnetic dielectric composition.Wherein one layer of ferromagnetic material is the reference layer for having fixed magnetisation direction,
Another layer of ferromagnetic material is then the memory layer of changeable magnetization direction, and its direction of magnetization can be with fixed magnetization layer phase
It is parallel or antiparallel.The resistance value of MTJ depends on the direction of magnetization of this two layers of ferrimagnet：They
The consistent then magnetic tunnel junction resistance in direction is with regard to low, otherwise magnetic tunnel junction resistance is just high.General high-resistance state is to patrol
Collect " 1 ", low resistance state is logical zero.The direction of magnetization for changing memory layer just changes MTJ
Resistance states, and the Resistance states of MTJ are detected it is known that storage content in Magnetic memory unit.
Different magnetic RAMs changes the direction of magnetization of memory layer using different methods.First generation field
Switch magnetization random access memory is to produce magnetic field in MTJ to change the magnetic field side of memory layer with larger current
To.New spin-torque switch magnetization random access memory (STT MRAM) is directly through magnetic using current impulse
Property tunnel knot, sense of current can change memory layer the direction of magnetization, so as to determine the electricity of MTJ
The logical states of resistance state and Magnetic memory unit.Not only energy consumption is very low for this new magnetic RAM, and
And because required switching current can reduce with the size of MTJ and reduce, therefore can be adapted to not
Carry out the demand that semiconductor chip junction spot size further reduces.But with the magnetic tunnel in magnetic RAM
The quantity of road knot is continuously increased, and size constantly reduces, to the technological requirement of manufacture also more and more higher, existing process
The uniformity of lower magneto-resistor is also worse and worse.
The data of magneto-resistor mnemon are read, it is to be in high-resistance state " 1 " to seek to detect its MTJ
Or low resistance state " 0 ".In order to accurately distinguish Resistance states, MTJ requirement reaches high magnetic resistivity (electricity
Hinder poor and low-resistance ratio).The magnetic RAM of one Large Copacity contains more than one hundred million individual MTJs,
If the standard deviation of their resistance value distribution is high, magnetic resistivity is low, and that will inevitably make high-impedance state
Distribution and low resistance state distribution, which exist, to be overlapped, as shown in Figure 1.
Existing reading technology is typically used to fix midpoint resistance as reference to determine the resistance of MTJ
The method of state：Average a number of high-resistance state and a number of low resistance state MTJ are used as midpoint
Resistance is compared with detected magnetic tunnel junction resistance.But due to the material and manufacturing process of MTJ
Limitation, one side magnetic resistivity is difficult to increase substantially, another aspect high capacity memory resistance standard difference increase
Greatly, the overlapping of high-impedance state distribution and low resistance state distribution is exacerbated.Even if their overlap is zero, one of they
Can be overlapping with being distributed with for midpoint reference resistance.Overlapping between distribution may result in can not possibly successfully distinguish it is all
The resistance state of mnemon and produce read error.
The read method for becoming reference with the magnetic tunnel of the Magnetic memory unit that is read in itself is referred to as from reference
Read.It is existing that from reference method general process is tediously long or weak output signal, some also needs to adjust various parameters,
The speed for sacrificing reading data adds the time delay of memory.
The content of the invention
In view of problems of the prior art, it is an object of the invention to provide a kind of magnetic RAM, profit
With the magneto-resistor bias-dependent of MTJ, the digital independent from reference is realized, solves and reads data pair
The standard deviation Spreading requirements of reference resistance it is harsh and the problem of cause read error rate high.
The present invention also provides a kind of Magnetic memory cell reading method of magnetic RAM.
The bias-dependent of the magneto-resistor of MTJ, the value of the magneto-resistor of MTJ with bias (or
Loading current) increase and reduce, and change amplitude it is particularly violent in high-impedance state.
Therefore, when MTJ is currently high-impedance state, applies different size of electric current, difference can be detected
The value of larger magneto-resistor, and the value of these magneto-resistors can be significantly greater than the value of the magneto-resistor of low resistance state.
Specifically, as shown in Fig. 2 when MTJ is currently high-impedance state, electric current I1 is applied, magneto-resistor
It is worth for R1H, applies electric current I2, the value of magneto-resistor is R2, and R1H is significantly greater than R2；MTJ is current
For low resistance state when, apply electric current I1, the value of magneto-resistor is that R1L, R1H and R2 are significantly greater than R1L.
Electric current I1 is conventional read current, and electric current I2 is write current, i.e., MTJ is changed into high-impedance state
Electric current；, can be accurate using the change of the value of magneto-resistor, that is, the bias-dependent of MTJ in itself
MTJ current state is obtained, so as to obtain the logic state of Magnetic memory unit.
The present invention provides a kind of magnetic RAM, including the array that multiple Magnetic memory units are formed, magnetic
Random access memory also includes, from reference to read module, the magnetic according to Magnetic memory unit to be used for from reference read module
Property tunnel knot change into the of-state voltage of high-impedance state, read the logic state of Magnetic memory unit.
Further, from reference to read module include state obtain cache module, high-impedance state state acquisition module with
And comparator, state obtain cache module and are used to obtain and cache the first of the MTJ of Magnetic memory unit
The voltage of state, first state are the current state of MTJ；High-impedance state state acquisition module is used to read
The voltage of second state, the second state are the state that MTJ changes into high-impedance state；Comparator is used to compare
The voltage of the voltage of first state and the second state.
Further, state, which obtains cache module, includes read current driver and voltage acquisition buffer circuit, reads electricity
Flow driver and be used for magnetropism tunnel knot application read current, voltage obtains buffer circuit and is used to obtain and cache magnetic
The first state voltage of tunnel knot.
Further, high-impedance state state acquisition module includes write current driver and voltage acquisition circuit, write current
Driver is used for magnetropism tunnel knot and applies the first write current, and MTJ is changed into high resistant by the first write current
State, voltage acquisition circuit are used for the voltage for obtaining the second state of MTJ.
Further, voltage acquisition circuit also includes bleeder circuit, for adjusting the voltage of the second state.
Further, the divider resistance of bleeder circuit has following relation：
RD/ (RD+RU)=I1/I2
Wherein, RD, RU are divider resistance, and I1 is read current, and I2 is the first write current.
The present invention also provides a kind of Magnetic memory cell reading method of above-mentioned magnetic RAM, including following
Step：
(1) state obtains the voltage of the first state of the MTJ of cache module acquisition Magnetic memory unit,
And cache；
(2) high-impedance state state acquisition module obtains the electricity of the second state of the MTJ of Magnetic memory unit
Pressure；
(3) comparator compares the voltage of first state and the voltage of the second state, if the voltage of first state is big
In the voltage of the second state, the first state of MTJ is high-impedance state；If the voltage of first state is less than
The voltage of second state, the first state of MTJ is low resistance state；
(4) if the first state of MTJ is low resistance state, MTJ is changed into low resistance state.
Further, step (2) comprises the following steps：
(21) MTJ of the write current driver magnetropism mnemon of high-impedance state read module applies the
One write current, MTJ is changed into high-impedance state；
(22) voltage acquisition circuit of high-impedance state read module obtains the state that MTJ changes into high-impedance state
Voltage.
Further, step (2) comprises the following steps：
(23) the write current driver magnetropism tunnel knot of high-impedance state read module applies the first write current, by magnetic
Property tunnel knot changes into high-impedance state；
(24) voltage acquisition circuit of high-impedance state read module obtains the MTJ after bleeder circuit adjusts
Change into the of-state voltage of high-impedance state.
Further, step (4) comprises the following steps：
(41) write current driver magnetropism tunnel knot the second write current of application of high-impedance state read module, second
MTJ is changed into low resistance state by write current.
Compared with prior art, magnetic RAM and its Magnetic memory cell reading method provided by the invention,
Have the advantages that：Using the magneto-resistor bias-dependent of MTJ, the digital independent from reference is realized,
Solving reading data causes read error rate is high to ask the standard deviation Spreading requirements harshness of reference resistance
Topic.
Brief description of the drawings
Fig. 1 is the distribution of resistance figure of the MTJ of the Magnetic memory unit of magnetic RAM；
Fig. 2 is the resistor current curve of the MTJ of the Magnetic memory unit of magnetic RAM；
Fig. 3 is the schematic diagram of the magnetic RAM of one embodiment of the present of invention；
Fig. 4 is the schematic diagram of the magnetic RAM of an alternative embodiment of the invention.
Embodiment
As shown in figure 3, the magnetic RAM of one embodiment of the present of invention, including multiple Magnetic memory lists
The array that member is formed, magnetic RAM also include, from reference to read module, being used for root from reference to read module
The of-state voltage of high-impedance state is changed into according to the MTJ of Magnetic memory unit, reads patrolling for Magnetic memory unit
The state of collecting.
Cache module, high-impedance state state acquisition module and comparator are obtained from state is included with reference to read module.
State obtains cache module and is used to obtain and cache the first state of the MTJ of Magnetic memory unit
Voltage, first state are the current state of MTJ, and electric capacity C1 caching first states are used in the present embodiment
Voltage.The voltage of other modes caching first state can certainly be used, the present invention is not restricted.
State, which obtains cache module, includes read current driver and voltage acquisition buffer circuit, and read current driver is used
Apply read current in magnetropism tunnel knot, voltage obtains buffer circuit and is used to obtaining and caching the of MTJ
One of-state voltage.
High-impedance state state acquisition module is used for the voltage for reading the second state, and the second state changes for MTJ
For the state of high-impedance state.
High-impedance state state acquisition module includes write current driver and voltage acquisition circuit, and write current driver is used for
Magnetropism tunnel knot applies the first write current, and MTJ is changed into high-impedance state by the first write current, and voltage obtains
Sense circuit is used for the voltage for obtaining the second state of MTJ.
Comparator is used to compare the voltage of first state and the voltage of the second state, if the voltage of first state is big
In the voltage of the second state, the first state of MTJ is high-impedance state；If the voltage of first state is less than
The voltage of second state, the first state of MTJ is low resistance state.
The Magnetic memory cell reading method of magnetic RAM in the present embodiment, comprises the following steps：
(1) state obtains the voltage of the first state of the MTJ of cache module acquisition Magnetic memory unit,
And cache；
(2) high-impedance state state acquisition module obtains the electricity of the second state of the MTJ of Magnetic memory unit
Pressure；
(3) comparator compares the voltage of first state and the voltage of the second state, if the voltage of first state is big
In the voltage of the second state, the first state of MTJ is high-impedance state；If the voltage of first state is less than
The voltage of second state, the first state of MTJ is low resistance state；
(4) if the first state of MTJ is low resistance state, MTJ is changed into low resistance state.
Step (2) comprises the following steps：
(21) MTJ of the write current driver magnetropism mnemon of high-impedance state read module applies the
One write current, MTJ is changed into high-impedance state；
(22) voltage acquisition circuit of high-impedance state read module obtains the state that MTJ changes into high-impedance state
Voltage.
Step (4) comprises the following steps：
(41) write current driver magnetropism tunnel knot the second write current of application of high-impedance state read module, second
MTJ is changed into low resistance state by write current.
Second write current and the first write current are in opposite direction.
The magnetic RAM of the present embodiment, using the magneto-resistor bias-dependent of MTJ, realize certainly
The digital independent of reference, solve reading data causes to read to the standard deviation Spreading requirements harshness of reference resistance
The problem of taking error rate high.
What is compared due to comparator is voltage signal, although the R2 as reference, as shown in Fig. 2 with the magnetic
High-impedance state resistance R1H of the tunnel knot under conventional read current and low resistance state resistance R1L has larger difference, still
Because its electric current I2 is larger so that V2=I2*R2 and V1H=I1*R1H difference can reduce.
As shown in figure 4, in an alternative embodiment of the invention, in order that the difference of two voltages is more accurately anti-
The difference of resistance is reflected, bleeder circuit can be increased in the voltage acquisition circuit of high-impedance state read module, for adjusting
The voltage of second state.
The divider resistance of bleeder circuit has following relation：
RD/ (RD+RU)=I1/I2
Wherein, RD, RU are divider resistance, and I1 is read current, and I2 is the first write current.
Voltage V2 ' the values of the second state after being so adjusted are I1*R2, and V2 ' and V1 ratio
It is exactly R2 and R1H or R1L ratio, more accurately reflects the difference of resistance.
, all can be with having foot from reference voltage no matter which Resistance states MTJ is in due to the addition of partial pressure
Enough big differences, enable data quick and precisely to read.
In the present embodiment, step (2) comprises the following steps：
(23) the write current driver magnetropism tunnel knot of high-impedance state read module applies the first write current, by magnetic
Property tunnel knot changes into high-impedance state；
(24) voltage acquisition circuit of high-impedance state read module obtains the MTJ after bleeder circuit adjusts
Change into the of-state voltage of high-impedance state.
Preferred embodiment of the invention described in detail above.It should be appreciated that the ordinary skill people of this area
Member makes many modifications and variations without creative work can according to the design of the present invention.Therefore, all skill
In art field technical staff under this invention's idea on the basis of existing technology by logic analysis, reasoning or
The available technical scheme of limited experiment, all should be in the protection domain being defined in the patent claims.
Claims (10)
1. a kind of magnetic RAM, including the array that multiple Magnetic memory units are formed, it is characterised in that magnetic
Random access memory also includes being used for according to Magnetic memory unit from reference to read module, the read module of reference certainly
MTJ change into the of-state voltage of high-impedance state, read the logic state of the Magnetic memory unit.
2. magnetic RAM as claimed in claim 1, it is characterised in that described to include certainly with reference to read module
State obtains cache module, high-impedance state state acquisition module and comparator, and the state obtains cache module and used
In obtaining and caching the voltage of the first state of the MTJ of Magnetic memory unit, the first state is magnetic
The current state of property tunnel knot；The high-impedance state state acquisition module is used for the voltage for reading the second state, described
Second state is the state that the MTJ changes into high-impedance state；The comparator is used for more described first
The voltage of state and the voltage of second state.
3. magnetic RAM as claimed in claim 2, it is characterised in that the state obtains cache module bag
Include read current driver and obtain buffer circuit with voltage, the read current driver applies for magnetropism tunnel knot
Read current, the voltage obtain buffer circuit and are used to obtain and cache the first state voltage of the MTJ.
4. magnetic RAM as claimed in claim 3, it is characterised in that the high-impedance state state acquisition module
Including write current driver and voltage acquisition circuit, the write current driver is used for magnetropism tunnel knot and applies the
The MTJ is changed into high-impedance state, the voltage acquisition circuit by one write current, first write current
For the voltage for the second state for obtaining the MTJ.
5. magnetic RAM as claimed in claim 4, it is characterised in that the voltage acquisition circuit also includes
Bleeder circuit, for adjusting the voltage of second state.
6. magnetic RAM as claimed in claim 5, it is characterised in that the divider resistance of the bleeder circuit
With following relation：
RD/ (RD+RU)=I1/I2
Wherein, RD, RU are divider resistance, and I1 is read current, and I2 is the first write current.
7. a kind of Magnetic memory cell reading method of magnetic RAM as described in claim any one of 1-6,
Characterized in that, the Magnetic memory cell reading method comprises the following steps：
(1) state obtains the voltage of the first state of the MTJ of cache module acquisition Magnetic memory unit, and delays
Deposit；
(2) high-impedance state state acquisition module obtains the electricity of the second state of the MTJ of the Magnetic memory unit
Pressure；
(3) comparator compares the voltage of first state and the voltage of the second state, if the voltage of the first state is big
In the voltage of second state, the first state of the MTJ is high-impedance state；If first shape
The voltage of state is less than the voltage of second state, and the first state of the MTJ is low resistance state；
(4) if the first state of MTJ is low resistance state, the MTJ is changed into low resistance state.
8. the Magnetic memory cell reading method of magnetic RAM as claimed in claim 7, it is characterised in that
Step (2) comprises the following steps：
(21) MTJ of the write current driver magnetropism mnemon of the high-impedance state read module applies the
One write current, the MTJ is changed into high-impedance state；
(22) voltage acquisition circuit of the high-impedance state read module obtains the MTJ and changes into high-impedance state
Of-state voltage.
9. the Magnetic memory cell reading method of magnetic RAM as claimed in claim 7, it is characterised in that
Step (2) comprises the following steps：
(23) the write current driver magnetropism tunnel knot of the high-impedance state read module applies the first write current, by institute
State MTJ and change into high-impedance state；
(24) voltage acquisition circuit of the high-impedance state read module obtains the magnetic tunnel after bleeder circuit adjusts
Road knot changes into the of-state voltage of high-impedance state.
10. the Magnetic memory cell reading method of magnetic RAM as claimed in claim 7, it is characterised in that
Step (4) comprises the following steps：
(41) the write current driver of the high-impedance state read module applies the second write current to the MTJ,
The MTJ is changed into low resistance state by second write current.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610283466.6A CN107342103A (en) | 2016-04-29 | 2016-04-29 | A kind of magnetic RAM and its Magnetic memory cell reading method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610283466.6A CN107342103A (en) | 2016-04-29 | 2016-04-29 | A kind of magnetic RAM and its Magnetic memory cell reading method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109961811A (en) * | 2017-12-22 | 2019-07-02 | 中电海康集团有限公司 | A kind of reading circuit of spin transfer torque MRAM |
| CN110197683A (en) * | 2018-02-27 | 2019-09-03 | 上海磁宇信息科技有限公司 | A kind of MRAM reading circuit with self-calibration function |
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| CN104380384A (en) * | 2012-04-11 | 2015-02-25 | 艾沃思宾技术公司 | Self-referenced sense amplifier for spin torque mram |
| US9111622B2 (en) * | 2012-05-09 | 2015-08-18 | Everspin Technologies, Inc. | Self referencing sense amplifier for spin torque MRAM |
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| CN102067230A (en) * | 2008-06-27 | 2011-05-18 | 希捷科技有限公司 | Spin-transfer torque memory non-destructive self-reference read method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109961811A (en) * | 2017-12-22 | 2019-07-02 | 中电海康集团有限公司 | A kind of reading circuit of spin transfer torque MRAM |
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| CN110197683A (en) * | 2018-02-27 | 2019-09-03 | 上海磁宇信息科技有限公司 | A kind of MRAM reading circuit with self-calibration function |
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