阅读说明：本技术 一种磁传感器 (A kind of Magnetic Sensor ) 是由 B·N·恩格尔 P·G·马瑟 于 2015-03-13 设计创作，主要内容包括：本发明涉及一种磁传感器。所公开的实施例涉及实现斩波技术和相关结构来抵消隧穿磁阻(TMR)场传感器中的磁1/f噪声作用。TMR场传感器包括：第一桥电路,其包括用于感测磁场的多个TMR元件；以及第二电路,其用于向各TMR元件施加双极电流脉冲。电流线连续地或顺序连接到场源,以接收双极电流脉冲。场传感器具有包括响应于双极脉冲的高输出和低输出的输出。此不对称响应允许进行场传感器中的1/f噪声减小的斩波技术。(The present invention relates to a kind of Magnetic Sensors.The disclosed embodiments are related to realizing wave chopping technology and dependency structure to offset the effect of the magnetic 1/f noise in tunnel magneto (TMR) field sensor.TMR field sensor includes: the first bridge circuit comprising for sensing multiple TMR elements in magnetic field；And second circuit, it is used to apply bipolar pulses to each TMR element.Current line continuously or is sequentially connected to field source, to receive bipolar pulses.It includes in response to the high output of bipolar pulse and the output of low output that field sensor, which has,.This asymmetry response allows to carry out the wave chopping technology that the 1/f noise in field sensor reduces.)

1. a kind of Magnetic Sensor (100), comprising:

A magnetoresistive sensor element (210) more than first, a magnetoresistive sensor element more than described first are coupled together becoming first Circuit (200)；And

Second circuit (400), the second circuit and first circuit (200) are adjacent and be configured as from described second The bipolar current source (500) of circuit (400) coupling receives bi-polar current signal (600),

Wherein each magnetic in a part of the second circuit (400) and more than described first a magnetoresistive sensor elements (210) Resistance sensor element (210) is adjacent, and

Wherein the bi-polar current signal (600) is configured as generating magnetic field to offset from more than described first a magnetoresistive sensor members At least part for the 1/f noise that at least one magnetoresistive sensor element (210) in part (210) generates.

2. Magnetic Sensor (100) according to claim 1, wherein each magnetoresistive sensor element (210) includes:

First ferromagnetic layer (212)；

Second ferromagnetic layer (214)；With

Middle layer (216) between first ferromagnetic layer (212) and the second ferromagnetic layer (214).

3. Magnetic Sensor (100) according to claim 2, wherein the middle layer (216) includes insulating materials.

4. Magnetic Sensor (100) according to claim 2 or 3, wherein described the of each magnetoresistive sensor element (210) One ferromagnetic layer (212) has the direction of magnetization rotated freely in magnetic field, and each magnetoresistive sensor element (210) is described Second ferromagnetic layer (214) has the fixed direction of magnetization.

5. Magnetic Sensor (100) according to any one of the preceding claims, wherein in response to receiving the bipolar electric It flows signal (600), the second circuit (500) is configured as in generation and more than described first a magnetoresistive sensor elements (210) The adjacent magnetic field of each magnetoresistive sensor element (210).

6. Magnetic Sensor (100) according to any one of the preceding claims, wherein the bi-polar current signal is to include Positive part (610), the negative part different from the positive part (610) (620), the beginning of the positive part (610) just The periodic signal of resetting pulse (611) and the negative resetting pulse (621) at the beginning of the negative part (620), and wherein The output of first circuit (200) includes respectively responsive to the positive part of the bi-polar current signal (600) and described The high output of negative part and low output.

7. Magnetic Sensor according to claim 5, wherein the bi-polar current signal (600) is believed with the output of the first circuit Number output data rate at least twice rate transmission, wherein the bi-polar current signal (600) with occupy it is described bipolar The positive part (610) and the negative part (620) of the different weight percentage in each period of current signal (600) are asymmetric, And wherein the high output from first circuit and the low output by sampling, be added and be averaged, with counteracting by institute The 1/f caused by least one magnetoresistive sensor element (210) more than first in a magnetoresistive sensor element (210) is stated to make an uproar At least part of sound.

8. Magnetic Sensor (100) according to any one of the preceding claims, wherein each magnetoresistive sensor element (210) It is one of tunnel magneto (TMR) element, giant magnetoresistance (GMR) element or anisotropic magnetoresistive (AMR) element.

9. Magnetic Sensor (100) according to any one of the preceding claims, wherein first circuit be bridge circuit or One of half-bridge circuit.

10. Magnetic Sensor (100) according to any one of the preceding claims, further includes:

A magnetoresistive sensor element (210) more than second, a magnetoresistive sensor element more than described second are coupled together becoming third Circuit；

4th circuit, the 4th circuit is configured as receiving bi-polar current signal (600), wherein one of the 4th circuit Divide adjacent with each magnetoresistive sensor element (210) in more than described second a magnetoresistive sensor elements (210)；

The multiple magnetoresistive sensor elements of third (210), the multiple magnetoresistive sensor elements of third are coupled together becoming the 5th Circuit；And

6th circuit, the 6th circuit is configured as receiving bi-polar current signal (600), wherein one of the 6th circuit Divide adjacent with each magnetoresistive sensor element (210) in the multiple magnetoresistive sensor elements of the third (210).

11. Magnetic Sensor (100) according to claim 8, wherein a magnetoresistive sensor element (210) quilt more than described first Be configured to sensing first direction on magnetic field, a magnetoresistive sensor element (210) more than described second be configured as sensing with institute The magnetic field in the orthogonal second direction of first direction is stated, and the multiple magnetoresistive sensor elements of the third (210) are configured as Sense the magnetic field on the third direction orthogonal with the first direction and second direction.

12. Magnetic Sensor (100) according to any one of the preceding claims, further includes:

It is fixed to be adjacent to at least one magnetoresistive sensor element (210) in more than described first a magnetoresistive sensor elements (210) The magnetic conductance (218) of position, wherein the magnetic conductance (218) is positioned on or below corresponding magnetoresistive sensor element (210).

13. Magnetic Sensor (100) according to any one of the preceding claims further includes being couple to first circuit (200) and the analog-digital converter (950) of one or more of the second circuit (400).

14. Magnetic Sensor (100) according to any one of the preceding claims, wherein second circuit (500) packet It includes:

Multiple current lines (410)；With

Multiplexing H-bridge circuit (800), for controlling the current path in each of the multiple current line (410).

15. Magnetic Sensor (100) according to claim 1, wherein the bi-polar current signal is periodic signal, the week Phase signal includes positive part (610), the negative part different from the positive part (610) (620), in the positive part (610) The positive resetting pulse (611) at beginning and negative resetting pulse (621) at the beginning of the negative part (620),

Wherein the positive resetting pulse (611) is configured as each magnetoresistive sensor element (210) of switching in a first direction The direction of magnetization of first ferromagnetic layer (212),

Wherein the weight bearing is set pulse (621) and is configured as first ferromagnetic layer of each magnetoresistive sensor element (210) (212) the direction of magnetization is switched to second direction opposite to the first direction,

Wherein the output of first circuit includes respectively responsive to the positive part of the bi-polar current signal and described negative Partial high output and low output, and

Wherein the high output from first circuit is sampled and is added with the low output, to eliminate by described first The 1/f noise caused by least one of described magnetoresistive sensor element in multiple magnetoresistive sensor elements is at least A part.

Technical field

The present invention relates generally to the field of magnetic field sensor, relate more specifically to reduce the noise in magnetic field sensor and offset Method.

Background technique

Magnetic field sensor is usually used in the various electronics such as computer, portable computer, media player, smart phone Device.In the presence of many technique/arrangements that can be used for detecting magnetic field.Tunnel magneto (TMR) is since it is compared to other Magnetic Sensors For it is advantageous in terms of sensitivity, power and processing cost, cause it be it is promising for hand-held set application magnetic strength survey Technology.The closely related technology of another kind in sensing magnetic fields is giant magnetoresistance (GMR).

TMR element non magnetic, insulating tunnel barrier separation two ferromagnetic layers by being made up of.One layer has " freedom " The direction of magnetization that ground rotates in magnetic field.Another layer has " fixation " reference magnetization, which is sensing concern Medium to low intensive magnetic field in when do not rotate.If the direction of magnetization of the two layers is parallel to each other, the electricity of tunnel barrier It hinders low.On the contrary, resistance is high when the direction of magnetization is antiparallel.Therefore magnetic field sensor based on TMR is changed by resistance by magnetic Field is converted into electric signal, and resistance change is caused by changing relative to the angular response of fixing layer in field magnetic free layer 's.

In such sensor, magnetic 1/f caused by being fluctuated because of the magnetic aligning in the region in one or two of layer Noise.These fluctuations are formed in the resistance change at the different markers occurred in echo signal as noise and can not be simple It filters out.1/f noise (also referred to as pink noise) be be inversely proportional with signal frequency spectral density (energy or power/ Hz signal or fluctuation processing).In addition, it is inclined also null field to be formed because of the difference of the magnetic aligning in the region in any magnetic film It moves, which may depend on temperature or stress in sensor.

Therefore, it would be desirable to be the system for effectively reducing 1/f noise and offset in TMR magnetic field sensor, device And method.

Summary of the invention

Certain embodiments of the present invention, which is provided using distinctive bipolar copped wave (chopping) technology, offsets TMR sensing The systems, devices and methods of 1/f noise and offset effect in device.As previously described, there are magnetic 1/ in TMR magnetic field sensor F magnetic noise and the noise can weaken the performance and sensitivity of these sensors.For around low with motion sensing application Frequently under (< 100Hz), the effect of 1/f magnetic noise becomes significant.The noise shows zero field-biased low frequency bending of TMR sensor bridge (meander), to reduce precision.

According to various embodiments of the present invention, wave chopping technology and dependency structure are realized to offset the magnetic in TMR field sensor 1/f noise effect and offset.TMR field sensor includes the first bridge circuit, and the first bridge circuit includes being configured to sense magnetic field Multiple TMR elements.Each TMR element includes the first ferromagnetic layer and the second ferromagnetic layer separated by non magnetic, insulating tunnel barrier. TMR field sensor further includes second circuit, and second circuit is configured to be adjacent to application bipolar current with each of TMR element Pulse.

In certain embodiments, second circuit includes second (fixation) ferromagnetic layer with each TMR element of the first bridge circuit The multiple in-built electrical streamlines being disposed adjacently.The current line is continuous or is sequentially connected to field source and applies to all current lines Add the bi-polar current signal.When applying bipolar pulses, magnetic field pulse is generated on first (freedom) ferromagnetic layer.According to First free ferromagnetic is switched to the first or second and is aligned by the polarity of applied current impulse, magnetic field generated (alignment)。

When application bipolar pulses adjacent with each of TMR element, free layer orientation switches to and current impulse Polarity alignment.After pulse completion, for the polarity of free layer alignment, measurement sensor output.In each free layer polarity The measured sensor output signal that place measures does not have reindexing, but the effect of magnetic 1/f noise and offset reindexing.This is not Symmetrical response allows wave chopping technology, in the art, with the repetition rate of at least twice of desired output data rate, In Apply magnetic field in first time period in a first direction, then applies magnetic field to second direction in second time period.The two The sensor output signal of period is combined, therefore is constructively added to sensing magnetic fields signal, but 1/f noise and offset are made With being cancelled.In one embodiment, the magnetic field applied on the first direction and the second direction and free ferromagnetic Alignment completely.In another embodiment, it is distributed for desired (or preferably) switching, in the first direction and described the The magnetic field applied on two directions is aligned with free ferromagnetic at deviation angle orientation.

All aspects of the invention will also be applied to the device based on GMR.It is disclosed herein that present invention may also apply to utilize For sensing any magnetic strength survey technology (for example, AMR, fluxgate, with the Hall of electromagnetic flux field concentrator) of the soft magnetic film in magnetic field.For For the sake of easy and clear, the TMR technology will be used as example in the present invention described in this document.

Detailed description of the invention

Exemplary embodiment of the present invention shown in reference to the accompanying drawings.These attached drawings be intended to it is illustrative, rather than limit Property processed.Although the present invention is usually to describe under the background of these embodiments, being not intended to by doing so will be of the invention The range special characteristic of embodiment that is limited to describe and describe.

Fig. 1 is the exemplary structure overview of TMR magnetic field sensor according to various embodiments of the present invention.

Fig. 2 is the cross-sectional view of single TMR element according to various embodiments of the present invention.

Fig. 3 is the exemplary diagram of two kinds of different copped wave states according to various embodiments of the present invention.

Fig. 4 is the exemplary diagram of the bridge circuit for Z axis according to various embodiments of the present invention.

Fig. 5 is exemplary control current signal according to various embodiments of the present invention.

Fig. 6 is illustrative sensors output signal according to various embodiments of the present invention.

Fig. 7 is the figure of confirmatory measurement result according to various embodiments of the present invention.

Fig. 8 is multiplexing (multiplexing) H reset for sequence with control logic according to various embodiments of the present invention The exemplary diagram of bridge.

Fig. 9 is the exemplary diagram of reading chain according to various embodiments of the present invention.

Those skilled in the art will recognize that various implementations and implementation of the invention can be practiced to specifications Example.All these implementations and embodiment are intended to be included within the scope of this invention.

Specific embodiment

In the following description, for purposes of illustration, sets forth specific details are to provide the understanding of the present invention.However, The present invention can practice in the case where some or all of without these details.The embodiment of the following description of the present invention can quilt It is incorporated to multiple and different electronic components, circuit, in device and system.The construction and device shown in block diagram is example of the invention The illustration of property embodiment and it will not be used as obscuring the pretext of broad teachings of the invention.The connection between component in attached drawing It is not limited to be directly connected to.On the contrary, can the connection between component be modified, reformatted or otherwise led to Intermediate member is crossed to be changed.

When specification quotes " one embodiment " or " embodiment ", it is intended to mean that the embodiment discussed is combined to retouch Special characteristic, structure, characteristic or the function stated are included at least one of the invention and expect in embodiment.Therefore, specification In different places there is the phrase " in one embodiment " and do not constitute multiple reference to single embodiment of the invention.

Various embodiments of the present invention for such as computer, portable computer, media player, smart phone, can It dresses the 1/f noise in TMR magnetic field sensor used in the various electronic devices such as electronic device and reduces and deviate reduction.TMR Magnetic field sensor and single TMR element therein can be incorporated in single component or comprising discrete component.In addition, this hair Bright embodiment can be applied to diversified technology and methods.

Fig. 1 shows the schematic diagram of TMR magnetic field sensor 100 according to various embodiments of the present invention.Magnetic field sensor 100 Including the first bridge circuit 200 energized by voltage source 300, the second circuit 400 energized by optionally stable field source 500.One In a embodiment, field source 500 is current source.First bridge circuit 200 includes multiple TMR elements 210.Bridge circuit 200 can be half Bridge circuit, full-bridge circuit, or any combination thereof.In one embodiment, the first bridge circuit 200 is that there are two circuit branch for tool Bridge circuit, the bridge output signal 260 between the two branches are in some intermediate point along branch.

Fig. 2 shows the cross-sectional views of single TMR element 210 according to various embodiments of the present invention.TMR sensor 210 by The first ferromagnetic layer 212 and the second ferromagnetic layer 214 separated by non magnetic, insulating tunnel barrier 216.In one embodiment, First layer 212 has the direction of magnetization 232 rotated freely in magnetic field.The second layer 214 has non-rotary when in magnetic field The fixed reference direction of magnetization 234.If the direction of magnetization of the two layers is parallel to each other, the resistance of tunnel barrier 216 is low.On the contrary Ground, when the direction of magnetization is antiparallel, resistance is high.Therefore TMR element is rung by the angle due to magnetic free layer relative to fixing layer Resistance caused by should changing in magnetic field changes, and magnetic field is converted into electric signal.Ferromagnetic layer 212 and 214 can be by such as Ni, Fe Or any suitable ferromagnetic material of its alloy is formed.Insulating tunnel barrier 216 can be by such as AlO_x、MgO_x、ZrO_x、TiO_x、HfO_x、 Or any combination thereof insulating material composition.

In one embodiment, the first ferromagnetic layer 212 is connected to the first conductor wire 224 by the first contact 222, and second Ferromagnetic layer 214 is connected to the second conductor wire 228 by the second contact 226, and the second contact 226 can be above the second ferromagnetic layer And lower contact.

In one embodiment, second circuit 400 includes being disposed adjacently with the second ferromagnetic layer 214 of each TMR element 210 Multiple in-built electrical streamlines 410.Current line 410 is connected, so that applying electric current arteries and veins to the current line for each TMR element 210 Punching.According to various embodiments, the connection of current line 410 can be continuous, sequence or time multiplexing.At another In embodiment, current line can also be disposed adjacently with the first ferromagnetic layer 212, or with the first ferromagnetic layer of each TMR element 210 and Both second ferromagnetic layers are disposed adjacently.First ferromagnetic layer 212 is patterned into the shape with major and minor axis.In zero magnetic field, The direction of magnetization of first ferromagnetic layer 212 is arranged along the long axis of element and can be along any one side of the axis in both direction It is upwardly-directed.By applying control current signal to current line 410, around the current line arround in region, generate induction magnetic .Since first layer 212 has the direction of magnetization 232 for rotating freely through and switching, the direction of magnetization 232, which will switch to, to be felt It answers under the action of magnetic field along the direction projected on its axis.Electricity as the exemplary illustration in Fig. 2, in current line 410 When stream has finger outwardly direction, the direction of magnetization 232 is directed toward a left side, has the component with the negative alignment in reference magnetization direction 234, and Free layer will be switched to the left；When the electric current in current line 410, which has, refers to inward direction, the direction of magnetization 232 is directed toward the right side, With the component with 234 positive alignment of reference magnetization direction, and free layer will be switched to the right.

Fig. 3 shows two kinds of different copped waves of the bridge circuit surveyed for X-Y axis magnetic strength according to various embodiments of the present invention The exemplary diagram of state.When applying current impulse to current line 410, generating on the first ferromagnetic layer has the direction of magnetization 232 Magnetic field pulse.According to the polarity of the current impulse applied, magnetic field generated by free layer direction 232 switch to have with The component of the positive or negative alignment in reference magnetization direction 234 of second ferromagnetic layer.

(A) of Fig. 3 shows the direction of magnetization 232 of the substantially positive alignment in the first ferromagnetic layer 212 and (B) of Fig. 3 is shown The direction of magnetization 232 of substantially negative alignment in first ferromagnetic layer 212.In one embodiment, the generated direction of magnetization 232 and ginseng Examine the intersecting angle between the direction of magnetization 234 is 45 degree or is 225 degree in negative alignment in positive alignment.Above angle of the crossing Degree is described for exemplary purpose that is clear and understanding.Intersecting angle can be appointing between 0 and ± 90 in positive alignment What angle is any angle between 180 and 270 in negative alignment.Here, figure is simplified, therefore each sensing element can table Show the array of sensing element.

Fig. 4 is two kinds of different copped wave states of the bridge circuit surveyed for Z axis magnetic strength according to various embodiments of the present invention Exemplary diagram.Z axis magnetic strength is surveyed, each TMR element integrates at least one magnetic conductance (flux guide) 218.Magnetic conductance 218 be the vertical rod of the high aspect ratio made of high-permeability material in each corresponding bridge leg, which, which has, terminates at magnetic strength Survey element to extrorse end.In one embodiment, magnetic conductance can above first (freedom) ferromagnetic layer 212 and/or under Fang Yiwei.Magnetic conductance acquires magnetic flux from the applied field being orientated in z-direction, and is bent field wire, to have close to magnetic conductance end Horizontal component.(A) of Fig. 4 shows+90 degree intersecting angles between the generated direction of magnetization 232 and reference magnetization direction 234 simultaneously And

(B) of Fig. 4 shows -40 degree intersecting angles.

Fig. 5 is exemplary control bi-polar current signal 600 according to various embodiments of the present invention.Resetting/stabilization field source 500 are configured to generate desired control electric current (such as, exemplary control bi-polar current signal 600 as shown in Figure 4) And apply it to current line 410.Bi-polar current signal 600 be include positive part 610 (+I_stab) and negative part 620 (- I_stab periodic signal).In one embodiment, bi-polar current signal 600 further includes positive 611 (+I_ of resetting pulse Reset), positive resetting pulse 611 is in the beginning of positive part 610, for switching the direction of magnetization.In one embodiment, bipolar Current signal 600 further includes negative resetting pulse 621 (- I_reset), and negative resetting pulse 621 is in the beginning of negative part 620, is used In the direction of magnetization of switching opposite direction.

According to output speed, power and noise requirements, positive/negative resetting pulse 611/621 can be the 10 of positive/negative part to 1M or more.Positive/negative part 610/620 can use any value, and in some cases, described value includes zero.In one embodiment In, positive part 610 is equal to negative part 620.In another embodiment, positive part 610 is different from negative part 620.

In one embodiment, 50% positive portion of bi-polar current signal 600 and each period for respectively accounting for current signal 600 Points 610 and negative part 620 it is symmetrical.In one embodiment, bi-polar current signal 600 and each period for accounting for current signal 600 Different weight percentage positive part 610 and negative part 620 it is asymmetric.In another embodiment, single I resetting pulse may be present With subsequent a lot of+I resetting pulse, wherein the initial measurement of sampling and each subsequent measurement phase after each+I resetting pulse Add.1/f noise is minimized, at least with the desired output data rate of the bridge output signal 260 of magnetic field sensor 100 Twice of rate applies bi-polar current signal 600.10 millisecond periods of the bi-polar current signal 600 in Fig. 5 are for exemplary Purpose, it is no intended to limit the invention to disclosed precise forms.In order to realize offset subtract each other and the asymmetric period, it can be achieved that The initial measurement stage.

Fig. 6 shows showing in response to the applied bi-polar current signal 600 in Fig. 4 according to various embodiments of the present invention Example property bridge output signal 260.Bridge output signal 260 has in response to 620 (- I_ of positive part 610 (+I_stab) and negative part Stab high output 261 and low output 262).Bridge output signal 260 asymmetrically responds symmetrical bi-polar current signal 600.One In a embodiment, height output 261 and low output 262 are positive.In another embodiment, height output 261 is positive and low output 262 are negative.For the field applied under this exemplary cases, positive output 261 has the absolute voltage higher than negative output 262 Value.As a result, output signal 260 has the field dependence value of ensemble average, although bi-polar current signal 600 is symmetrical and flat with zero Mean value.In typical circuit implementation, two values will be sampled and keep and be added together, and generate output signal.Only Want bi-polar current signal 600 at least twice of the desired output data rate of the bridge output signal 260 of magnetic field sensor 100 Rate apply, the realization of bi-polar current signal 600 just do not interfere the normal operating of magnetic field sensor 100 to export.

Fig. 7 shows the figure for extending the confirmatory measurement result in the period according to various embodiments of the present invention.The figure packet It includes for generating 271 (V of positive signal sequence_pos) individual signals 261 many samples, including for generating negative signal sequence 272 (V_neg) negative signal 262 many samples and resultant signal (V_tot).In Fig. 6, Y-axis be subtract each other with constant DC voltage it is inclined It moves, so that all results are fitted on single precisely figure line.After certain delay after each resetting pulse, positive signal 271 is taken With each point of negative signal 272, with eliminate transformation when ring (ringing).Positive signal and negative signal are accurately anti-at low frequency Phase.Therefore, resultant signal 273 is acted on the 1/f noise that positive signal 271 and negative signal 272 identification to cancel each other out is substantially reduced.

Fig. 8 shows the multiplexing H-bridge circuit reset for sequence with control logic according to various embodiments of the present invention 800.Multiplexing H-bridge circuit 800 forms multiple single H-bridge circuits of the current line 410 for each TMR element 210.Multiplexing H-bridge circuit 800 include multiple transistors 810 for controlling the current flow path in current line 410.For example, p1 transistor and n1 crystal Pipe can be closed, therefore the electric current in current line 410 can follow the first resetting path 801, and then p2 and n2 can be closed, with such It pushes away, to allow remaining current line to there is similar sequence to reset path.Then, p2 and n0 in this case, pass through control institute It is expected that the cut-off/close of transistor combination, creates the second resetting path in opposite direction.In one embodiment, individually (sequentially) current path of each current line 410 is controlled.In another embodiment, the current path quilt of all current lines 410 Control simultaneously is the single joint current path for all current lines.By correctly controlling the logic of multiplexing H-bridge circuit, magnetic field Sensor will execute the first measurement after the first resetting pulse sequence, store the first measured value, execute the second resetting arteries and veins The second measurement after sequence is rushed, the second measured value is stored, is summed to two measured values to generate total output.Show in Fig. 8 Mixing H-bridge circuit out can easily be expanded or shunk, to adapt to the current line and transistor of various quantity.Multiplexing H-bridge circuit 800 are used only for exemplary purpose.In the range and equivalency range of application, it can be mixed the various modifications of H-bridge circuit.

Fig. 9 shows exemplary reading chain according to various embodiments of the present invention.Reading chain 900 includes multiple components, packet Include the bipolar resetting contact maker (chop) 910 of magnetic, Magnetic Sensor 920, electric contact maker 930, low-noise amplifier (LNA) 940, modulus (A/D) converter 950, electrolytic interrupter (dechop) 960, magnetic solution contact maker 970 etc..Electric contact maker 930, low-noise amplifier (LNA) 940, A/D converter 950 and electrolytic interrupter 960 form the electric part 902 for reading chain, and reading chain, which may also include, to be used for The component of axis multiplexing (axes muxing), down-sampling, averaging etc..In one embodiment, the bipolar resetting contact maker 910 of magnetic It is operated in 1~50,000Hz frequency range, electrolytic interrupter 960 operates under 40kHz frequency, but usually magnetic interrupter frequency Twice of rate, and magnetic solution contact maker 970 matches the frequency of the bipolar resetting contact maker 910 of magnetic.In another embodiment, above Component can also be worked according to application with other operating frequencies or order.Contact maker-solution contact maker keeps electricity to that can form sampling Road, the sampling hold circuit allow to carry out signal summation under each state, to generate such as the sensor output 273 in Fig. 7.

Those skilled in the art will recognize that various implementations can be realized in described configuration, it is all these Implementation is within the scope of the present invention.For example, adjustable various parameters, farthest to eliminate TMR magnetic field sensing 1/f noise in device.It is some including resetting pulse width and amplitude, bi-polar current signal period, bipolar electric in these parameters Flow the duty ratio (space ratio) etc. of signal.

Above description of the invention is described for purpose that is clear and understanding above.It is arranged in and limits the invention to Disclosed precise forms.Various modifications form can be in the range and equivalency range of application.