CN203894396U - Remodeled Wheatstone half-bridge circuit and sensor - Google Patents
Remodeled Wheatstone half-bridge circuit and sensor Download PDFInfo
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- CN203894396U CN203894396U CN201420199856.1U CN201420199856U CN203894396U CN 203894396 U CN203894396 U CN 203894396U CN 201420199856 U CN201420199856 U CN 201420199856U CN 203894396 U CN203894396 U CN 203894396U
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Abstract
The utility model discloses a remodeled Wheatstone half-bridge circuit and a sensor. The remodeled Wheatstone half-bridge circuit comprises two half-bridge resistance units; one end of one half-bridge resistance unit is in electric connection with one end of the other half-bridge resistance unit, and the other end of each half-bridge resistance unit is respectively provided with a second connection conductor and a third connection conductor. The characteristics are that asymmetry of resistance of the two half-bridge resistance units in a zero bias field is no more than +/- 5%, wherein at least one half-bridge resistance unit is formed by at least two resistance branches in parallel connection or in series connection. The remodeled Wheatstone half-bridge circuit is provided with parallel resistors to generate square items to effectively weaken noise response caused by asymmetry of resistance values of the two half-bridge resistance units, or employs resistors in series connection to completely counteract increase of asymmetry of resistance values caused by a bias filed, thereby greatly raising a signal to noise ratio.
Description
Technical field
The utility model relates to a kind of sensing circuit, is specifically related to a kind of improvement of favour stone half-bridge circuit, and the sensor that adopts this circuit, for feeble signal field is accurate, detects.
Background technology
Sensor technology is widely used in the every field such as traffic, space flight and aviation, finance, industry, biomedicine and smart mobile phone, panel computer, digital camera, interactive game.
Along with developing rapidly of sensor application field, in the urgent need to improving sensor, detect the ability of feeble signal field, the stability of detection and reduce costs, and suppress the external interference such as noise, be to improve the key factor of above-mentioned performance index.
Wheatstone bridge is a kind of common sensor circuit, and detection signal is exerted one's influence to resistance, such as adopting mistor, voltage dependent resistor (VDR), thermistor etc. according to detected object, changes the resistance in electric bridge, with this detection signal.Conventionally use the method that suppresses noise for adopting traditional Hui Sitong half-bridge or full-bridge circuit, yet traditional wheatstone bridge circuits require the resistance of each resistance of electric bridge in full accord.But in reality, once due to mass production processes repeatability problem and when having bias-field to cause resistance incomplete same, it suppresses noise ability and will have a greatly reduced quality.Industry member large-scale production level just at present, is less than +/-1% and all has certain challenge even if will very realize the asymmetry of resistance.Therefore, toward contact, must go filtering to there is the noise of characteristic frequency by means of various signal filter circuits.
Fig. 1 has illustrated a kind of sensor schematic diagram that uses traditional Hui Sitong half-bridge circuit.As shown in Figure 1, on substrate 1, by two resistance and wire, formed Hui Sitong half-bridge circuit, wherein, the resistance of a resistance 5 is R1, and the resistance of another resistance 4 is R2.Between two resistance, through the first wire 6, form and be electrically connected to, the other end of resistance 5 is provided with the second wire 2, and the other end of resistance 4 is provided with privates 3.
The resistance of two resistance is respectively,
R1=R0-Rw+R1s+R1n (1)
R2=R0+Rw+R2s+R2n (2)
Resistance R 1 when wherein null field resistance R 0 is null field and the average electrical resistance of R2; When asymmetry resistance R w is null field 1/2nd of the difference of resistance R 1 and R2 resistance; Resistance asymmetry is defined as Rw/R0, conventionally much smaller than 1; Signal resistance R1s and R2s are respectively the variation of the resistance value that resistance R 1 and R2 cause because of signal place; Noise resistance R1n and R2n are respectively the variation of the resistance value that R1 and R2 cause because of noise.
When detecting local signal field, the noise field gradient coming from the outside is much smaller than detected signal field gradient.When resistance R 1 and R2 spacing much smaller than noise field change apart from time, can approximate expression noise resistance be R1n=R2n=Rn.
When half-bridge circuit is applied to bias voltage Vin, output voltage V out is
Vout=Vin×R2/(R1+R2)
= 0.5Vin×[1+(Rw-(R1s- R2s)/2)/[R0+(R1s+R2s)/2+Rn]] (3)
When no signal is inputted, the output voltage that noise causes changes Vn and is
Vn=0.5Vin×[1+(Rw/R0)/(1+(Rn/R0)] (4)
When having bias-field, the output voltage that noise causes changes Vn and is
Vn=0.5Vin×[1+(Rwb/Rb)/(1+(Rn/Rb)] (5)
Wherein, biasing resistor Rb=R0+dRb, dRb is the variation of the resistance value that causes of biasing place; Rwb=Rw+dRwb, dRwb be R1 and R2 under bias-field resistance value difference 1/2nd.In constant bias after the match, Rwb/Rb=Rw/R0; Under gradient bias-field, common Rwb/Rb>Rw/R0.
Obviously, the asymmetry Rw of two half-bridge resistances has caused the noise response in output signal, reduces this asymmetry (Rw/R0) and contributes to suppress noise.Yet, reduce the restriction that resistance inconsistency is subject to production technology and assemble ability.
Apply bias magnetic field and can encourage magnetic signal and significantly improve signal intensity, be conducive to improve signal to noise ratio (S/N ratio).But non-constant gradient bias magnetic field can significantly increase resistance asymmetry (Rw/R0).In addition,, although can adopt large bias-field to be conducive to reduce asymmetry by (Rw/Rb), bias-field size is subject to can not excessive biasing and cause the restriction that magnetic resistance is saturated.
Therefore the single order item [(Rw/R0)/(1+ (Rn/Rb)] of, depending merely on traditional half-bridge comes the effect of attenuate acoustic noise limited.
Fig. 2 has illustrated noise on an impact of using the Magnetic Sensor output signal of traditional Hui Sitong half-bridge circuit.It is set to, magnetic resistance is the tunnel magnetoresistive of reluctivity 200%, the magnetic-field-sensitive direction of two tunnel magnetoresistives is identical, the asymmetry of its null field resistance is +/-1%, without additional bias-field, a constant some signal Magnetic Field Source is closely first passed through R2 through R1 again by sensor top, and the maximum resistance change that signal magnetic field produces is 0.002% of null field resistance, and with the magnetic field producing by trigonometric function current lead, comes simulated environment noise to disturb above half-bridge circuit.
As seen from Figure 2, under the noise with signal formed objects, output signal can demonstrate the fluctuation that noise causes, and when noise is signal 5 times time, the waveform that recognize and judge output signal is suitable difficulty.
Summary of the invention
Goal of the invention of the present utility model is to provide a kind of remodeling Hui Sitong half-bridge circuit, reduces the not quite identical impact causing of resistance value in half-bridge, and the impact of the resistance value inconsistency variation particularly causing due to bias magnetic place improves detection sensitivity; Another goal of the invention of the present utility model is to provide the sensor of this remodeling of application Hui Sitong half-bridge circuit.
To achieve the above object of the invention, the technical solution adopted in the utility model is: a kind of remodeling Hui Sitong half-bridge circuit, comprise two half-bridge resistance units, one end of two half-bridge resistance units is electrically connected to through the first bonding conductor jointly, the other end of two half-bridge resistance units is respectively equipped with the second bonding conductor and the 3rd bonding conductor, the asymmetry of the resistance of two half-bridge resistance units when zero offset field be not more than ± and 5%, wherein at least one half-bridge resistance unit is in parallel or in series by least two resistance branch.
In technique scheme, the resistance of two half-bridge resistance units should equate in theory, but in actual fabrication, certainly exist deviation, as described in the background art, the resistance asymmetry of two half-bridge resistance units is larger in the definition of resistance asymmetry, and the impact of noise is larger.
Adopt after resistance branch formation in parallel half-bridge resistance unit, can produce quadratic component, by the asymmetry item (Rw/R0) to much smaller than 1, press quadratic power decay, effectively suppress noise response.
And adopt after resistance branch half-bridge resistance unit in series, can offset the dRwb of the resistance variations item causing along resistance spacing due to bias-field, and guarantee that null field resistance asymmetry is not because bias-field increases, only improve signal intensity and do not increase noise, thereby effectively improve signal to noise ratio (S/N ratio).
Preferred technical scheme, in two half-bridge resistance units, a half-bridge resistance unit consists of a resistance branch, and another half-bridge resistance unit is in parallel or in series by two resistance branch, and the other end of these two resistance branch is electrically connected to by the second bonding conductor.
Further technical scheme, two resistance of described two resistance branch are equidistantly symmetrically distributed in the both sides of another branch road resistance along its sensitive direction, and its null field resistance asymmetry be not more than ± 5%.
In technique scheme, each resistance branch is a resistance or is in series or in parallel to form by a plurality of resistance.
A sensor, is provided with above-mentioned remodeling Hui Sitong half-bridge circuit, and described two half-bridge resistance units sensitive resistance that the value of having a resistance changes by responding to detected signal forms.Can use separately above-mentioned remodeling Hui Sitong half-bridge circuit, also can form Hui Sitong full-bridge circuit by remodeling Hui Sitong half-bridge circuit.
When as Magnetic Sensor, described sensitive resistance is magnetic resistance, and the magnetic-field-sensitive direction of each magnetic resistance is identical or arrange on the contrary.Described magnetic resistance can be tunnel magnetoresistive, giant magnetoresistance, anisotropic magnetoresistive, Hall magnetic resistance.
Further technical scheme, is provided with bias magnetic field, or the on the contrary setting identical with bias magnetic field direction of the magnetic-field-sensitive direction of described magnetic resistance.
Preferred technical scheme, described bias magnetic field is linear magnetic field gradient, and the magnetic-field-sensitive direction of magnetic resistance is identical and be disposed in linear bias magnetic field range, and not to be biased magnetic field saturated for magnetic resistance simultaneously.
In technique scheme, described bias magnetic field adopts one pole or multistage, and the South Pole-arctic-South Pole or the arctic-South Pole-arctic combination, produces linear magnetic field gradient in the scope that can distribute at magnetic resistance.
Bias magnetic field can be implemented by the combination of single or multiple permanent magnets or coil magnet, can also at hard magnetic bias film or the loop construction of chip surface, be implemented by produced by micro processing.
When using gradient bias magnetic field situation, the output waveform that Hard Magnetic and soft magnetism signal detected has obvious different characteristic.
Because technique scheme is used, the utility model compared with prior art has following advantages:
1, the utility model wherein at least one half-bridge resistance unit by resistance branch structure in parallel or be connected into, the quadratic component producing due to parallel resistance far surpasses to weakening the effect of resistance inconsistency the first power item that traditional circuit produces, or because resistance in series has suppressed the resistance asymmetry increase that bring in biasing place, therefore the remodeling Hui Sitong half-bridge circuit that, the utility model provides and sensor can more effectively suppress noise response and improve signal to noise ratio (S/N ratio);
While 2, adopting the utility model to prepare Magnetic Sensor, thereby bias magnetic field is set and can significantly improves signal intensity raising signal to noise ratio (S/N ratio), the quadratic component producing in conjunction with parallel resistance, or in conjunction with resistance in series, suppressed the resistance asymmetry increase that bring in biasing place, can suppress to greatest extent noise response and improve signal to noise ratio (S/N ratio);
3, due to above-mentioned extraordinary inhibition noise ability, can avoid using noise filter circuit, and can relax the requirement to manufacturing process tolerance and build-up tolerance, be conducive to improve yield rate and reduce costs;
4, adopting central magnetic field is zero and during the contrary bias magnetic field of left and right magnetic direction, can clearly distinguish soft magnetism and the Hard Magnetic feature of magnetic signal.
Accompanying drawing explanation
Fig. 1 is the sensor construction schematic diagram that uses Hui Sitong half-bridge circuit in prior art;
Fig. 2 adopts the circuit of Fig. 1 as Magnetic Sensor signal output map under noise when without bias magnetic field;
Fig. 3 is the sensor construction schematic diagram of the utility model embodiment mono-;
Fig. 4 be in embodiment mono-, adopt Fig. 3 structure as Magnetic Sensor the signal output map under noise;
Fig. 5 is the comparison diagram that uses the ratio of the signal under the noise difference with sensor shown in Fig. 1 of the utility model embodiment mono-Magnetic Sensor.
Fig. 6 is the sensor construction schematic diagram of the utility model embodiment bis-;
Fig. 7 is the sensor construction schematic diagram of the utility model embodiment tri-;
Fig. 8 is the magnetic sensor arrangement schematic diagram of the utility model embodiment tetra-;
Fig. 9 is the output waveform of Magnetic Sensor detected Hard Magnetic signal under noise of the utility model embodiment tetra-.
Figure 10 is the output waveform of the Magnetic Sensor detected soft magnetism signal under noise described in the utility model embodiment tetra-.
Figure 11 is the comparison diagram of signal to noise ratio (S/N ratio) difference between the Magnetic Sensor of the utility model embodiment mono-and embodiment tetra-and the Magnetic Sensor that adopts traditional Hui Sitong half-bridge circuit.
Figure 12 is the magnetic sensor arrangement schematic diagram of the utility model embodiment five;
Figure 13 is the output waveform of Magnetic Sensor detected Hard Magnetic signal under noise of the utility model embodiment five.
Figure 14 is the output waveform of the Magnetic Sensor detected soft magnetism signal under noise described in the utility model embodiment five.
Figure 15 is the magnetic sensor arrangement schematic diagram of the utility model embodiment six.
Figure 16 is the output waveform of the traditional Magnetic Sensor detected Hard Magnetic signal under noise under bias magnetic field.
Figure 17 is that the Magnetic Sensor of the utility model embodiment six is in bias magnetic field lower time, the output waveform of detected Hard Magnetic signal under noise.
Figure 18 is the magnetic sensor circuit structural representation of the utility model embodiment seven.
Embodiment
Below in conjunction with drawings and Examples, the utility model is further described:
Embodiment mono-: a kind of remodeling Hui Sitong half-bridge circuit, comprise two half-bridge resistance units, one end first bonding conductor 6 of two half-bridge resistance units is electrically connected to, one of them half-bridge resistance unit consists of two resistance branch parallel connections, in each resistance branch, be provided with a resistance 5, the other end of this half-bridge resistance unit is provided with the second bonding conductor 2, two resistance branch connect and compose parallel connection by the second bonding conductor 2, another half-bridge resistance unit forms single resistance branch by a resistance 4, the other end of this half-bridge resistance unit is provided with the 3rd bonding conductor 3, and two parallel resistance branch roads are with respect to the symmetrical setting of half-bridge resistance unit of single resistance branch.
Shown in accompanying drawing 3, for adopting the magnetic sensor chip of above-mentioned remodeling Hui Sitong half-bridge circuit, comprise substrate 1, resistance and conductor are arranged in substrate 1.Wherein, resistance 4 and resistance 5 are magnetic resistance, resistance 5 is by two magnetic resistance parallel connections, a half-bridge resistance unit that has formed Hui Sitong half-bridge circuit, and another magnetic resistance has formed another half-bridge resistance unit of Hui Sitong half-bridge circuit, two magnetic resistance in parallel are symmetrically distributed in the both sides of single magnetic resistance along its magnetic-field-sensitive direction.The second bonding conductor 2, the 3rd bonding conductor 3, the first bonding conductor 6 are arranged at the two ends of above-mentioned magnetic-field-sensitive resistance, are respectively used to connect biased electrical pressure side, earth terminal and the signal output part of conducting channel.
Wherein, magnetic resistance can be tunnel magnetoresistive, giant magnetoresistance, anisotropic magnetoresistive, Hall magnetic resistance.
With reference to Fig. 3, the resistance of two magnetic resistance in parallel is respectively,
R11=R0-Rw+R11s+R11n (6)
R12=R0+Rw+R12s+R12n (7)
The resistance of another magnetic resistance is
R2=0.5(R0+R2s+R2n) (8)
Signal resistance R11s, R12, and R2s is respectively detected magnetic signal to two magnetic resistance R11 in parallel, R12, and the variation of the resistance value of magnetic resistance R2 generation; Noise resistance R11n, R12n, and R2n is respectively outside noise and disturbs two magnetic resistance R11 in parallel, R12, and the variation of the resistance value that produces of magnetic resistance R2, can be approximately R11n=R12n=R2n=Rn.
The resistance of parallel resistance is
R1=0.5(R0+R1sm+Rn)(1-((Rw-R1sd)/(R0+R1sm+R1n))^2) (9)
Wherein, R1sm=(R11s+R12s)/2, R1sd=(R11s-R12s)/2;
The output voltage of favour stone half-bridge is
Vout=0.5Vin/(1-0.5((Rw-Rs12d)/(R0+Rs12m+Rn))^2) (10)
When no signal, the output voltage that noise causes changes Vn and is
Vn=0.5Vin/[1-0.5((Rw/R0)/(1+(Rn/R0)))^2] (11)
Compare with the single order item (seeing formula 4) of traditional sensors, the second order quadratic term that parallel resistance described in the utility model produces ((Rw/R0)/(1+ (Rn/R0))) ^2 more effectively attenuate acoustic noise disturbs.
Fig. 4 is the impact of noise on Magnetic Sensor output signal in the present embodiment.It is set to, magnetic resistance is the tunnel magnetoresistive of reluctivity 200%, the magnetic-field-sensitive direction of two tunnel magnetoresistives is identical, the asymmetry of two magnetic resistance null field resistance in parallel is +/-1%, without additional bias-field, a constant some signal Magnetic Field Source is closely first passed through R2 through R1 again by sensor top, and the maximum resistance change that signal magnetic field produces is 0.002% of null field resistance, and half-bridge circuit top comes simulated environment noise to disturb with the magnetic field producing by trigonometric function current lead.
Visible, even if at 50 times under the noise of signal, the utility model Magnetic Sensor used still can guarantee good output waveform and signal to noise ratio (S/N ratio), it suppresses noise ability and is much better than traditional Magnetic Sensor.
Fig. 5 is Magnetic Sensor and the comparison diagram that uses the traditional half-bridge Magnetic Sensor output signal-noise ratio under similarity condition shown in Fig. 1 in the present embodiment.
Under equal noise, the signal to noise ratio (S/N ratio) of the utility model Magnetic Sensor is far above traditional half-bridge Magnetic Sensor.Even if resistance asymmetry differs from one times than traditional half-bridge Magnetic Sensor, the signal to noise ratio (S/N ratio) of the utility model Magnetic Sensor still obviously exceeds traditional half-bridge Magnetic Sensor.
Therefore, the utility model Magnetic Sensor can be tolerated larger resistance asymmetry.
Embodiment bis-
Fig. 6 is the another kind design of the utility model magnetic sensing chip.Two magnetic resistance in parallel itself are comprised of the magnetic resistance of two or more parallel connections.
Embodiment tri-
Fig. 7 is the another kind design of magnetic sensing chip described in the utility model.Magnetic resistance itself is comprised of the magnetic resistance of a plurality of series connection.
Embodiment tetra-
As shown in Figure 8, on the magnetic sensor chip basis of embodiment mono-, increase and apply gradient bias magnetic field, form the Magnetic Sensor with bias magnetic field.Bias magnet 7 in assembling module 8 and 9 is implemented magnetic field biasing in a side that departs from zero offset field, center to the magnetic resistance of described formation Hui Sitong half-bridge, and offset position is in the middle of the magnetic pole of two, north and south, and magnetic field gradient approaches minimum.Now, the output voltage of Hui Sitong half-bridge is
Vout=0.5Vin/(1-0.5((Rwb/Rb-R12sd/Rb)/(1+R12sm/Rb+Rn/Rb))^2) (12)
Wherein, R12sm=(R1s+R2s)/2, R12sd=(R1s-R2s)/2;
When no signal, the output voltage that noise causes changes Vn and is
Vn=0.5Vin/[1-0.5((Rwb/Rb)/(1+(Rn/Rb)))^2] (13)
Although bias magnetic field may cause resistance asymmetry (Rwb/Rb) to increase, also cause signal terms (R12sd/Rb) and significantly increase (R12sm/Rb).When the increase ratio of resistance asymmetry is less than the increase ratio of signal terms, the raising of signal to noise ratio (S/N ratio) will be benefited from.
Fig. 9 is the output waveform of Magnetic Sensor detected Hard Magnetic signal under noise described in embodiment tetra-.
This Magnetic Sensor is specifically set to, magnetic-field-sensitive resistance adopts reluctivity for 200% tunnel magnetoresistive thin film, inconsistent resistance R w is the +/-4% of null field resistance R 0, biasing 40% is that biasing resistor Rb is 140% of null field resistance R 0, a Hard Magnetic signal that can not be biased magnetic field magnetisation reversion passes through Magnetic Sensor by Magnetic Sensor top along bias magnetic field direction, and the maximum resistance change that this Hard Magnetic signal magnetic field produces is 0.2% of null field resistance R 0.
As seen from Figure 9, when noise causes null field resistance variations 2%, the Magnetic Sensor that the utility model provides still can keep good Hard Magnetic signal output waveform.Because bias magnetic field cannot this Hard Magnetic signal of magnetization inversion, in Fig. 9, two signal peaks in left and right are suitable.
Figure 10 is the output waveform of Magnetic Sensor detected soft magnetism signal under noise described in embodiment tetra-.It arranges with upper identical.
Figure 10 shows, when noise causes null field resistance variations 2%, the Magnetic Sensor that the utility model provides still can keep good soft magnetism signal output waveform.Because bias magnetic field can this soft magnetism signal of magnetization inversion, and soft magnetism signal changes with the size of bias magnetic field, and in Fig. 9, two signal peaks in left and right differ obvious.
Comparison diagram 9 can find out with Figure 10, and the Magnetic Sensor that the utility model provides can be picked out by signal peak characteristic difference soft magnetism or the Hard Magnetic attribute of detected magnetic signal.
Figure 11 is the contrast of Magnetic Sensor described in employing the utility model embodiment tetra-and the signal to noise ratio (S/N ratio) of conventional half bridge topology Magnetic Sensor when having or not bias magnetic field.
Visible, no matter whether to setover, the signal to noise ratio (S/N ratio) of Magnetic Sensor described in the utility model is all far above conventional half bridge topology Magnetic Sensor.Under the condition allowing, apply bias magnetic field, can improve to greatest extent the anti-noise jamming ability of Magnetic Sensor described in the utility model.
Embodiment five
As shown in figure 12, two parallel resistance branch roads are distributed in one side of the half-bridge resistance unit of single resistance branch, two remodeling half-bridge circuits are symmetrically distributed in both sides, bias magnetic field center and have formed the intelligent stone full-bridge circuit of retrofiting, its magnetic-field-sensitive opposite direction, the magnetic-field-sensitive direction of each remodeling half-bridge circuit magnetic resistance is identical with the lateral offset magnetic direction of position, and other setting is identical with embodiment tetra-.Can also only use single half-bridge circuit.
Figure 13 is the Magnetic Sensor half-bridge of detected Hard Magnetic signal and output waveform of full-bridge circuit under noise described in embodiment five.
As seen from Figure 13, full-bridge circuit has lower noise response or higher noise resisting ability than half-bridge circuit.Meanwhile, because bias magnetic field cannot magnetization inversion Hard Magnetic signal, the output waveform that is positioned at both sides, bias magnet center has identical amplitude direction.
Figure 14 is the Magnetic Sensor half-bridge of detected soft magnetism signal and output waveform of full-bridge circuit under noise described in embodiment five.
Because soft magnetism signal can be biased magnetic field magnetisation reversion, its output waveform that is positioned at magnetic blow out centre both sides has positive and negative contrary amplitude.
Embodiment six
As shown in figure 15, two resistance in series branch roads are symmetrically distributed in the both sides of the half-bridge resistance unit of single resistance branch, form Hui Sitong half-bridge circuit.
Shown in accompanying drawing 15, for adopting the magnetic sensor chip of above-mentioned remodeling Hui Sitong half-bridge circuit, comprise substrate 1, resistance and conductor are arranged in substrate 1.Wherein, resistance is magnetic resistance, two magnetic resistance 5-1 and 5-2 have been composed in series a half-bridge resistance unit of Hui Sitong half-bridge circuit, and another magnetic resistance (resistance 4) has formed another half-bridge resistance unit of Hui Sitong half-bridge circuit, the magnetic resistance of two series connection is symmetrically distributed in the both sides of single magnetic resistance along its magnetic-field-sensitive direction.The second bonding conductor 2, the 3rd bonding conductor 3, the first bonding conductor 6 are arranged at the two ends of above-mentioned magnetic-field-sensitive resistance, are respectively used to connect biased electrical pressure side, earth terminal and the signal output part of conducting channel.
When applying linear bias field, the resistance of two series connection magnetic resistance is respectively,
R11=0.5(Rb-Rwb+R11s+R11n） (14)
R12=0.5(Rb+Rwb+R12s+R12n) (15)
After its series connection, resistance is,
R1=Rb+0.5(R11s+R12s+R11n+R12n) (16)
Asymmetric Rwb of resistance that visible biasing place produces connects and offset completely because of resistance.
The resistance of another magnetic resistance is
R2= Rb+Rw+R2s+R2n (17)
When no signal is inputted, the output voltage that noise causes changes Vn and is
Vn=0.5Vin×[1+(Rw/Rb)/(1+(Rn/Rb)] (18)
Compare with formula (5), because resistance asymmetry Rw is much smaller than Rwb, resistance asymmetry does not change because increase bias-field, and the utility model series connection method used possesses the noise output much smaller than classic method.
It is worthy of note, this example has illustrated to depart from the application of magnetic blow out centre biasing, and this principle is also applicable to the application in magnetic blow out centre biasing, the i.e. occasion of Rb=R0.
Figure 16 is conventional half bridge topology Magnetic Sensor detected Hard Magnetic signal output waveform under noise while using bias magnetic field.Although be biased magnetic field, contribute to suppress noise, the change in resistance producing at noise be null field resistance 0.1% time, severe jamming signal output waveform.
Figure 17 is the output waveform of Magnetic Sensor detected Hard Magnetic signal under noise described in embodiment six.Even the change in resistance that noise produces be null field resistance 0.5% time, still can keep good signal output waveform.Compare with Figure 16 visible, be eager to excel 5 times of conventional half bridge topology Magnetic Sensors of the antijamming capability of the utility model Magnetic Sensor described in embodiment six.
Embodiment seven
As shown in figure 18, two half-bridge branch road resistance respectively have a plurality of identical magnetic resistance (MR) to be composed in series, and the resistance of a branch road in magnetic induction direction with equidistant (W) from the both sides that are distributed in another branch road resistance.
Claims (10)
1. a remodeling Hui Sitong half-bridge circuit, comprise two half-bridge resistance units, one end of two half-bridge resistance units is electrically connected to through the first bonding conductor jointly, the other end of two half-bridge resistance units is respectively equipped with the second bonding conductor and the 3rd bonding conductor, it is characterized in that: the asymmetry of the resistance of two half-bridge resistance units when zero offset field be not more than ± and 5%, wherein at least one half-bridge resistance unit is in parallel or in series by least two resistance branch.
2. remodeling Hui Sitong half-bridge circuit according to claim 1, it is characterized in that: in two half-bridge resistance units, a half-bridge resistance unit consists of a resistance branch, another half-bridge resistance unit is in parallel or in series by two resistance branch, and the other end of these two resistance branch is electrically connected to by the second bonding conductor.
3. remodeling Hui Sitong half-bridge circuit according to claim 1 and 2, is characterized in that: form two parallel connections or the resistance in series of a resistance branch, be equidistantly symmetrically distributed in the both sides of another branch road resistance along its induction direction.
4. remodeling Hui Sitong half-bridge circuit according to claim 1 and 2, is characterized in that: each resistance branch is a resistance or is in series or in parallel to form by a plurality of resistance.
5. a sensor, is characterized in that: be provided with the remodeling Hui Sitong half-bridge circuit described in arbitrary claim in claim 1 to 4, described two half-bridge resistance units sensitive resistance that the value of having a resistance changes by responding to detected signal forms.
6. sensor according to claim 5, is characterized in that: when as Magnetic Sensor, described sensitive resistance is magnetic resistance, and the magnetic-field-sensitive direction of each magnetic resistance is identical or arrange on the contrary.
7. sensor according to claim 6, is characterized in that: described magnetic resistance is selected from tunnel magnetoresistive, giant magnetoresistance, anisotropic magnetoresistive or Hall magnetic resistance.
8. according to the sensor described in claim 6 or 7, it is characterized in that: when when being provided with the Magnetic Sensor of bias magnetic field, or the on the contrary setting identical with bias magnetic field direction of the magnetic-field-sensitive direction of described magnetic resistance.
9. sensor according to claim 8, it is characterized in that: when conduct is provided with the Magnetic Sensor of bias magnetic field, described bias magnetic field is linear magnetic field gradient, and the magnetic-field-sensitive direction of magnetic resistance is identical and be disposed within the scope of linear magnetic field gradient, and not to be biased magnetic field saturated for magnetic resistance simultaneously.
10. sensor according to claim 9, is characterized in that: when conduct is provided with the Magnetic Sensor of bias magnetic field, described bias magnetic field adopts one pole or multistage, in the scope distributing, produces linear magnetic field gradient at magnetic resistance.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103901365A (en) * | 2013-12-20 | 2014-07-02 | 叶友忠 | Modified Wheatstone half-bridge circuit and sensor |
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| CN103901365A (en) * | 2013-12-20 | 2014-07-02 | 叶友忠 | Modified Wheatstone half-bridge circuit and sensor |
| CN103901365B (en) * | 2013-12-20 | 2017-04-12 | 叶友忠 | Modified Wheatstone half-bridge circuit and sensor |
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