CN202421321U - Current sensor - Google Patents
Current sensor Download PDFInfo
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- CN202421321U CN202421321U CN 201120565375 CN201120565375U CN202421321U CN 202421321 U CN202421321 U CN 202421321U CN 201120565375 CN201120565375 CN 201120565375 CN 201120565375 U CN201120565375 U CN 201120565375U CN 202421321 U CN202421321 U CN 202421321U
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- mtj
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- temperature compensation
- current sensor
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Abstract
The utility model provides a current sensor. The current sensor comprises Wheatstone bridges integrally arranged in the same chip, as well as an MTJ temperature compensation magneto-resistor and a current conductor, wherein each Wheatstone bridge consists of MTJ (Magnetic Tunnel Junction) magneto-resistors; the current conductor is close to the Wheatstone bridges, and tested current can be charged into the current conductor; permanent magnets are arranged at the periphery of the MTJ temperature compensation magneto-resistor and enable the magnetization directions of both a free layer and a pinning layer of the MTJ temperature compensation magneto-resistor to be in reverse parallel with each other, so that the MTJ temperature compensation magneto-resistor is in the high-resistance status that the resistance value only changes along with the temperature within the measuring range; and the Wheatstone bridges and the MTJ temperature compensation magneto-resistor are connected in series to obtain stable output voltages at two ends of the Wheatstone bridges, and a magnetic field generated by the tested current is obtained through the stable output voltage, so that the tested current value can be acquired. By adopting the above structure, the current sensor provided by the utility model can compensate temperature drift and has the advantages of high sensitivity, wide linear range, low power consumption and good temperature characteristic.
Description
Technical field
The utility model relates to a kind of current sensor, and especially a kind of tunnel junction magneto-resistor that adopts is the current sensor that contains the temperature compensation magneto-resistor of sensitive element.
Background technology
It is sensitive element that current sensor commonly used adopts Hall element usually; Also there are employing anisotropic magnetoresistance (AMR) or giant magnetoresistance (GMR) to be the current sensor of sensitive element; Its common ground is it all is to belong to magnet-sensitive element, realizes the measurement to its size of current through the magnetic field that the tested electrified wire of sensitivity produces.
The sensitivity of Hall element is extremely low; The current sensor that with the Hall element is sensitive element uses the magnetism gathering rings structure to amplify magnetic field usually, improves the Hall output sensitivity, thereby has increased the volume and weight of sensor; It is big that the while Hall element has power consumption, the defective of poor linearity.Though its remolding sensitivity Hall element of AMR element is high a lot; But its range of linearity is narrow; Simultaneously be that the current sensor of sensitive element need be provided with the set/reset coil it is preset-reset operation with AMR; Cause the complicacy of its manufacturing process, being arranged on of loop construction also increased power consumption when increasing size.The current sensor that with the GMR element is sensitive element has higher sensitivity than Hall current sensor, but its range of linearity is on the low side.
Tunnel junction magneto-resistor (MTJ; Magnetic Tunnel Junction) element is the novel magnetoresistance effect sensor that begins commercial Application in recent years; Its utilization be the tunneling magnetoresistance (TMR of magnetoresistance effect material; Tunnel Magnetoresistance), mainly show in the magnetoresistance effect material variation, the resistance generation significant change of magnetoresistance effect material along with the external magnetic field size and Orientation; Than before institute finds that the AMR element of also practical application has bigger resistance change rate, the while has better temperature stability with respect to Hall element and GMR element.The current sensor that with the MTJ element is sensitive element has better temperature stability than Hall current sensor, higher sensitivity, and lower power consumption, better the linearity does not need extra magnetism gathering rings structure; Have better temperature stability with respect to the AMR current sensor, higher sensitivity, the wideer range of linearity does not need extra set/reset loop construction; Has better temperature stability with respect to the GMR current sensor, higher sensitivity, lower power consumption, the wideer range of linearity.
Though it is the current sensor of sensitive element that the temperature characterisitic of MTJ current sensor is better than with Hall element, AMR element and GMR element, still there is the temperature drift phenomenon in actual use.
Summary of the invention
The utility model provides a kind of current sensor, is sensitive element with MTJ, and the current sensor that can compensate temperature drift, has highly sensitively, and the range of linearity is wide, and is low in energy consumption, and volume is little, the advantage of good temp characteristic.
For achieving the above object; The utility model provides a kind of current sensor; Comprise the integrated Wheatstone bridge of forming by the MTJ magneto-resistor and one or more MTJ temperature compensation magneto-resistor, the current lead that is arranged in the same chip; Said current lead is near Wheatstone bridge and wherein can be connected with tested electric current; Be provided with permanent magnet around the said MTJ temperature compensation magneto-resistor; This permanent magnet is antiparallel the DOM of the free layer of MTJ temperature compensation magneto-resistor and the DOM of pinning layer so that MTJ temperature compensation magneto-resistor is in resistance only temperature variant high-impedance state in measurement range; Said Wheatstone bridge and MTJ temperature compensation magneto-resistor are in series and obtain stable output voltage with the two ends at Wheatstone bridge, thereby and obtain the magnetic field that tested electric current produces through this stable output voltage and obtain tested current value.
Preferably, said MTJ magneto-resistor and MTJ temperature compensation magneto-resistor are formed by one or more MTJ element connected in series, and a plurality of MTJ elements have identical temperature characterisitic, R
HValue and R
LValue.
Preferably, Wheatstone bridge is the Hui Sitong half-bridge.
Preferably, said Wheatstone bridge is the Hui Sitong full-bridge.
The utility model adopts above structure, and the current sensor that can compensate temperature drift has highly sensitively, and the range of linearity is wide, and is low in energy consumption, and volume is little, the advantage of good temp characteristic.
Description of drawings
Fig. 1 is the synoptic diagram of tunnel junction magnetoresistive element (MTJ).
Fig. 2 is applicable to the magnetic resistance change rate curve synoptic diagram of the MTJ element of linear magnetic field measurement along the hard axis direction.
Fig. 3 is MTJ element 1 series connection and form the concept map of an equivalent MTJ magneto-resistor.
Fig. 4 is the magnetic resistance change rate curve map of MTJ magneto-resistor under the different temperatures.
Fig. 5 is the concept map that a kind of MTJ favour stone is recommended half-bridge.
Fig. 6 is the typical output map that MTJ recommends half-bridge.
Fig. 7 is the analog result that MTJ recommends the output of half-bridge under different temperatures.
Fig. 8 is the concept map that a kind of MTJ favour stone is recommended full-bridge.
Fig. 9 is the typical output map that MTJ recommends full-bridge.
Figure 10 is the analog result that MTJ recommends the output of full-bridge under different temperatures.
Figure 11 is the concept map that a kind of MTJ that contains thermo-compensator recommends the half-bridge current sensor chip.
Figure 12 is the concept map that MTJ that another kind contains thermo-compensator recommends the half-bridge current sensor chip.
Figure 13 is the concept map that a kind of MTJ that contains thermo-compensator recommends full-bridge current sensor chip.
Figure 14 is the test result that increases temperature compensation resistance front and back MTJ push-pull bridge current sensor temperature coefficient under the different magnetic field.
Embodiment
Fig. 1 is the concept of function sketch of a MTJ multilayer film element.MTJ element 1 generally comprises ferromagnetic layer or artificial inverse ferric magnetosphere (Synthetic Antiferromagnetic, SAF) 5, and the tunnel barrier layer 4 between the ferromagnetic layer of lower floor or 3, two magnetosphere of SAF layer on upper strata.In this structure, the ferromagnetic layer on upper strata has been formed the magnetic free layer with (SAF layer) 5, and its DOM changes with the change of external magnetic field.The ferromagnetic layer of lower floor (SAF layer) 3 is fixing magnetospheres, because its DOM is to be pinned at a direction, under general condition can not change.Pinning layer is deposited iron magnetosphere or SAF layer above or below antiferromagnetic layer 2 normally.Mtj structure normally is deposited on the top of the Seed Layer 10 of conduction, and the top of mtj structure is an electrode layer 6 simultaneously.The Seed Layer 10 of MTJ and the measured resistance value 11 between the protective seam 6 are represented the relative DOM of free layer 5 and pinning layer 3.When ferromagnetic layer (SAF layer) 5 the DOM on upper strata was parallel with the DOM of the ferromagnetic layer of lower floor 3, the resistance 11 of whole element was at low resistance state.When the DOM antiparallel of ferromagnetic layer (SAF layer) 5 the DOM on upper strata and the ferromagnetic layer of lower floor 3, the resistance 11 of whole element is at high-impedance state.Through known technology, the resistance of MTJ element 1 can be along with externally-applied magnetic field linear variation between high-impedance state and low resistance state.
Fig. 2 is the magnetic resistance change rate curve synoptic diagram that is applicable to the MTJ element 1 of linear magnetic field measurement.Curve of output is saturated when the resistance of low resistance state 12 and high-impedance state 13.When pinning layer DOM 8 and free layer DOM 7 were parallel, the resistance of MTJ element 1 was a low resistance state 12; When pinning layer DOM 8 and free layer DOM 7 antiparallels, the resistance of MTJ element 1 is a high-impedance state 13.Before reaching capacity, curve of output is to be linearly dependent on externally-applied magnetic field H.Curve of output usually not with the point symmetry of H=0, H
oBe saturation field 21, the typical offset between 22, the corresponding zone of saturation of low resistance state 12 is more near the point of H=0, H
oValue be commonly called " orange skin effect (Orange Peel) " or " Nai Er be coupled (Neel Coupling) "; Its representative value is usually between 1 to 25 Oe; Relevant with the structure and the flatness of ferromagnetic thin film in the MTJ element 1, depend on material and manufacturing process.In unsaturated zone, the curve of output equation can be approximated to be:
(1)
Fig. 3 is MTJ element 1 series connection and form the synoptic diagram of an equivalent MTJ magneto-resistor.The MTJ magneto-resistor that is together in series can reduce noise, improves the stability of sensor.In the MTJ magneto-resistor, the bias voltage of each MTJ element 1 reduces with the increase of magnetic tunnel-junction quantity.The reduction of electric current need produce a big voltage, thereby has reduced shot noise, along with the ESD that increasing of magnetic tunnel-junction also strengthened sensor simultaneously is stable.In addition, along with the noise that increases the MTJ magneto-resistor of MTJ element 1 quantity correspondingly reduces, this be because each independently the mutual incoherent random behavior of MTJ element 1 on average fallen.
Fig. 4 is the magnetic resistance change rate curve map of MTJ magneto-resistor under the different temperatures; Can be clear that the rising along with temperature, the resistance of MTJ magneto-resistor is not obvious in the variation of low resistance state, and high-impedance state has tangible reduction phenomenon; In general, the resistance of MTJ magneto-resistor reduces with the rising of temperature.
Fig. 5 is the concept map that a kind of MTJ favour stone is recommended half-bridge.As shown in the figure, pinning layer DOM 8 antiparallels of two MTJ magneto-resistor R1, R2, free layer DOM 7 changes with the outfield, steady voltage V
BiasPut on pad V
BiasEnd and GND end, pad V
OUTBe output terminal.When to recommending the half-bridge sensor when applying an outfield; Magnetic-field component along sensitive direction 9; The resistance of R2 can decrease when the resistance of magneto-resistor R1 increased; The resistance of R2 can increase thereupon when applying resistance that rightabout outfield can make R1 and reduce, and the typical curve of output of recommending half-bridge is as shown in Figure 6.
Fig. 7 is the analog result that MTJ recommends the output of half-bridge under different temperatures.As shown in the figure, half-bridge circuit is along with its output voltage of rising of temperature can correspondingly reduce.
Fig. 8 is the concept map that a kind of MTJ favour stone is recommended full-bridge.As shown in the figure, four MTJ magneto-resistor R11, R12, R21, R22 connect steady voltage V with the full-bridge form
BiasPut on pad V
BiasEnd and GND end; Pad V+ and V-are output terminal; The free layer DOM 7 of four magneto-resistors changes with the outfield; The magneto-resistor R11 of relative position is identical with the pinning layer DOM 8 of R22 (R12 and R21), pinning layer DOM 8 antiparallels of the magneto-resistor R11 of adjacent position and R12 (R11 and R21 etc.), the sensitive direction 9 of bridge circuit and pinning layer DOM 8 parallel or antiparallels.
When to recommending full-bridge sensors when applying an outfield; Two other is in the magneto-resistor R12 of relative position and the resistance of R21 can correspondingly reduce when along the magnetic-field component of sensitive direction 9 magneto-resistor R11 and the R22 resistance of relative position being increased; The resistance of R12 and R21 can correspondingly increase when the direction in change outfield can make R11 and R22 resistance reduce;---a pair of resistance increases another resistance is reduced---can increase the sensitivity output of bridge circuit to use the multiple measurement outfield of two pairs of magneto-resistors that opposite response is arranged, and therefore is called as " push-pull type " bridge circuit.The voltage of its output terminal is:
(2)
The output of bridge circuit is defined as:
In recommending full-bridge circuit, the magnetic resistance change rate function of MTJ magneto-resistor is:
Then:
Promptly realize recommending the output of full-bridge, the analog result of its curve of output is as shown in Figure 9.
Figure 10 is the analog result that MTJ recommends the output of full-bridge under different temperatures.As shown in the figure, full-bridge circuit is along with its output voltage of rising of temperature can correspondingly reduce.
We are not difficult to find out that the reason of the temperature drift of MTJ favour stone bridge circuit is because the variation of MTJ element resistance causes the variation of its voltage.For the temperature drift phenomenon, a thermo-compensator can be set temperature is floated compensate.Figure 11 is a kind of thermo-compensator R that contains
T(16) MTJ recommends the concept map of half-bridge current sensor chip.As shown in the figure; Half-bridge circuit 14 is together in series with temperature compensation resistance 16, is provided with permanent magnet 17 its free layer DOM 7 of biasing of high-intensity magnetic field around the temperature compensation resistance 16, makes itself and pinning layer DOM 8 be antiparallel and is in high-impedance state 13; Insensitive to the outfield; Its resistance 11 only with temperature variation, is provided with lead 20 in the chip simultaneously in measurement range, electric current 19 to be measured flows into chip through pad Iin+; Flow out through pad Iin-, the magnetic field 21 that magneto-resistor half-bridge circuit 14 is produced through responsive tested electric current 19 is to measure electric current to be measured again.Temperature compensation resistance 16 can calculate according to resistance and the temperature coefficient of half-bridge arm resistance R1, R2 in the ideal case; When magneto-resistor during with temperature variation; The resistance of temperature compensation resistance and half-bridge circuit reduces simultaneously or raises; Big variation just can not take place in the voltage that puts on the electric bridge two ends, thereby realizes the compensation to temperature drift.
Figure 12 is that another kind contains thermo-compensator R
T(16) MTJ recommends the concept map of half-bridge current sensor chip.As shown in the figure, the pinning layer DOM 8 of arm resistance R1 and R2 is identical, and free layer DOM 7 changes with the outfield; Half-bridge circuit 14 is together in series with temperature compensation resistance 16, is provided with permanent magnet 17 its free layer DOM 7 of biasing of high-intensity magnetic field around the temperature compensation resistance 16, makes itself and pinning layer DOM 8 be antiparallel and is in high-impedance state 13; Insensitive to the outfield; Only with temperature variation, electric current 19 to be measured gets into through pad Iin+ its resistance 11 in measurement range, and Iin-flows out; The U type lead 20 of built-in chip type be positioned at arm resistance R1 and R2 above or below, the magnetic field 21 that half-bridge circuit 14 is produced through responsive electric current 19 is to measure electric current to be measured.
Figure 13 contains thermo-compensator R
T(16) MTJ recommends the concept map of full-bridge current sensor chip.As shown in the figure, four MTJ magneto-resistor R11, R12, R21, R22 form Hui Sitong full-bridge and temperature compensation resistance R
T(16) series connection; The pinning layer DOM 8 identical free layer DOM 7 of four MTJ magneto-resistors change with the outfield, are provided with permanent magnet 17 its free layer DOM 7 of biasing of high-intensity magnetic field around the temperature compensation resistance 16, make itself and pinning layer DOM 8 be antiparallel and are in high-impedance state 13; Insensitive to the outfield; Its resistance 11 only with temperature variation, is provided with U type lead 20 in the chip simultaneously in measurement range, electric current 19 to be measured flows into chip through pad Iin+; Flow out through pad Iin-, the magnetic field 21 that magneto-resistor full-bridge circuit 14 is produced through responsive electric current 19 is to measure electric current to be measured again.
The output V of bridge diagram
OUT(T) and real output value V
OUTCan fit to linear function with temperature variation:
K wherein
TBe the temperature coefficient of output voltage, the temperature coefficient k of Hall current sensor commonly used
TBe several thousand PPM/ ℃.Figure 14 is the test result that increases temperature compensation resistance front and back MTJ push-pull bridge current sensor temperature coefficient under the different magnetic field, and we can be clearly seen that after temperature compensation resistance was set, its temperature coefficient greatly reduced, and the good results are evident in temperature compensation.
More than combine diagram to be illustrated to the specific embodiment of the utility model, clearly, on the basis of the scope of not leaving the utility model and spirit, can much revise prior art and technology.In the affiliated technical field of the utility model, the common knowledge of a GPRS just can be carried out diversified change in the technological main idea scope of the utility model.
Claims (4)
1. current sensor; It is characterized in that: comprise the integrated Wheatstone bridge of forming by the MTJ magneto-resistor and one or more MTJ temperature compensation magneto-resistor, the current lead that is arranged in the same chip; Said current lead is near Wheatstone bridge and wherein can be connected with tested electric current; Be provided with permanent magnet around the said MTJ temperature compensation magneto-resistor; This permanent magnet is antiparallel the DOM of the free layer of MTJ temperature compensation magneto-resistor and the DOM of pinning layer so that MTJ temperature compensation magneto-resistor is in resistance only temperature variant high-impedance state in the measurement range of this current sensor; Said Wheatstone bridge and MTJ temperature compensation magneto-resistor are in series and obtain stable output voltage with the two ends at Wheatstone bridge, obtain tested current value thereby the output voltage of this current sensor through the two ends of Wheatstone bridge obtains the magnetic field that tested electric current produces.
2. current sensor according to claim 1 is characterized in that: said MTJ magneto-resistor and MTJ temperature compensation magneto-resistor are formed by one or more MTJ element connected in series, and a plurality of MTJ elements have identical temperature characterisitic, R
HValue and R
LValue.
3. current sensor according to claim 1 is characterized in that: said Wheatstone bridge is the Hui Sitong half-bridge.
4. current sensor according to claim 1 is characterized in that: said Wheatstone bridge is the Hui Sitong full-bridge.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201120565375 CN202421321U (en) | 2011-12-30 | 2011-12-30 | Current sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201120565375 CN202421321U (en) | 2011-12-30 | 2011-12-30 | Current sensor |
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| Publication Number | Publication Date |
|---|---|
| CN202421321U true CN202421321U (en) | 2012-09-05 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201120565375 Withdrawn - After Issue CN202421321U (en) | 2011-12-30 | 2011-12-30 | Current sensor |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102419393A (en) * | 2011-12-30 | 2012-04-18 | 江苏多维科技有限公司 | Current sensor |
| CN110987028A (en) * | 2019-11-22 | 2020-04-10 | 珠海格力电器股份有限公司 | Temperature compensation system and compensation method of magnetic encoder |
-
2011
- 2011-12-30 CN CN 201120565375 patent/CN202421321U/en not_active Withdrawn - After Issue
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102419393A (en) * | 2011-12-30 | 2012-04-18 | 江苏多维科技有限公司 | Current sensor |
| WO2013097542A1 (en) * | 2011-12-30 | 2013-07-04 | 江苏多维科技有限公司 | Current sensor |
| CN102419393B (en) * | 2011-12-30 | 2013-09-04 | 江苏多维科技有限公司 | Current sensor |
| US9465056B2 (en) | 2011-12-30 | 2016-10-11 | MultiDimension Technology Co., Ltd. | Current sensor with temperature-compensated magnetic tunnel junction bridge |
| CN110987028A (en) * | 2019-11-22 | 2020-04-10 | 珠海格力电器股份有限公司 | Temperature compensation system and compensation method of magnetic encoder |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20120905 Effective date of abandoning: 20130904 |
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| RGAV | Abandon patent right to avoid regrant |