CN105372606A - Flux quantum counting device and flux quantum counting method without dead zone time - Google Patents
Flux quantum counting device and flux quantum counting method without dead zone time Download PDFInfo
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- CN105372606A CN105372606A CN201510079231.0A CN201510079231A CN105372606A CN 105372606 A CN105372606 A CN 105372606A CN 201510079231 A CN201510079231 A CN 201510079231A CN 105372606 A CN105372606 A CN 105372606A
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Abstract
The invention provides a flux quantum counting device and a flux quantum counting method without dead zone time. Two flux lock loops respectively connected with SQUIDs of different sensitivity are reset and then the working points thereof are locked, a flux interlock unit is employed to make the other flux lock loop in a working point-locked state when one flux lock loop is reset, so that the flux change within the dead zone time from resetting to locking of the reset flux lock loop is acquired, and the working point of the reset flux lock loop after relocking can be compensated and judged. The range of the readout circuit can be extended infinitely within the normal working interval of the SQUIDs through orderly active resetting and relocking, and the linearity in the whole range is improved. Moreover, the risk of working point jump within the dead zone time for the traditional flux quantum counting method is avoided effectively, the structure design and spatial layout of the two SQUIDs of different sensitivity are optimized, and the error of measurement caused by channel crosstalk and magnetic gradient is reduced.
Description
Technical field
The present invention relates to and belong to superconductor electronic technology field, especially a kind of based superconductive quantum inteferometer realizes the device and method without Dead Time fluxon counting.
Background technology
Superconducting quantum interference device (SQUID) (SQUID:SuperconductingQUantumInterferenceDevice) is a kind of magnetic flux voltage converter built based on Josephson junction, also be the highest Magnetic Sensor of current known sensitivity, have numerous application in atomic low-intensity magnetic field field of detecting such as biological magnetic, geophysics and low-field nuclear magnetic resonances.
Under current offset mode of operation, the output voltage V at SQUID two ends presents cyclical variation along with the increase of outside magnetic flux Φ, this is the basic place that its range is huge, but the V-Φ characteristic of SQUID is not linear, usual needs pass through flux locked loop (FluxLockLoop) linearization to reach practical object after noise matching, and the main operational principle of FLL is the change of being offset external magnetic field by the tickler on SQUID side, its working point is made to remain in V-Φ curve near certain position, but which also limits range and the bandwidth of SQUID simultaneously.
Under maskless working environment, especially motion or the serious environment of magnetic interference, the SQUID sensing circuit based on FLL is very easy to limit by range and causes circuit losing lock.Although make SQUID sensing circuit relock by the mode resetted, there is unpredictable jump in the working point after circuit relocks, and SQUID measurement is relative quantity, cannot carry out interpolation, thus the data recorded after making losing lock loses meaning.
Prior art has the wide range SQUID sensing circuit by Flux modulation, tested magnetic field is coupled to respectively by pick-up winding in the SQUID of two different sensitivity, and these two SQUID have oneself independently FLL circuit, although this way method greatly extends dynamic range, if but the SQUID sensing circuit losing lock of muting sensitivity, the problem jumped in working point exists equally, and the linearity in whole range can affect by pick-up winding and the effective operation interval of sensing circuit.In addition, easily erroneous judgement is caused because of non-linear and resolution when adopting the two-stage topologies of this technology to realize wide range, adopt multilevel topology to be then difficult to balance channel crosstalk and the measuring error caused by magnetic gradient, greatly can increase the complicacy of system simultaneously.
After prior art carries out logic decision, control waveform generation and shaping by fluxmeter counting unit in addition, by discharge switch, reset operation is carried out to integrator, realize fluxon counting, wherein the positive and negative count pulse of fluxmeter counting unit exports as circuit, and exports common for Waveform Reconstructing with integrator.Although this technology has relatively simple circuit structure, but there is Dead Time when resetting to integrator, if this section of Dead Time field fluctuation is more than a Φ 0, so measurement data will be discontinuous and the unknown, and its result is the same with the problem jumped in working point noted earlier.
In sum, the SQUID sensing circuit of existing wide range is not that to there is range inadequate, causing because there is Dead Time working point to jump uncontrollable problem exactly, greatly have impact on superconducting magnetic sensor in the widespread use of industry, scientific research and medical field and popularization.
Summary of the invention
The shortcoming of prior art in view of the above, in order to solve the problem of SQUID sensing circuit range deficiency under motion or the serious environment of magnetic interference, the invention provides a kind of fluxon counting assembly without Dead Time and method, not only by positive return in an orderly manner and the range relocking its sensing circuit of infinite expanding in the normal operation interval of SQUID, and the linearity improved in its whole range, and can effectively avoid traditional fluxon method of counting in Dead Time, there is the risk of working point jump.
For realizing above-mentioned target and other related objectives, the invention provides a kind of fluxon counting assembly without Dead Time, comprise: the first flux locked loop and the second flux locked loop, connecting respectively is a highly sensitive SQUID and relative the 2nd SQUID for muting sensitivity relatively; Threshold detection unit, connects the output terminal of described first flux locked loop and the second flux locked loop respectively; Reset unit, accesses described first flux locked loop and the second flux locked loop respectively; Magnetic flux interlocking unit, is connected between described threshold detection unit and reset unit; Data acquisition unit, the output terminal connecting described first flux locked loop and the second flux locked loop, connect described threshold detection unit output terminal and connect the input end of described magnetic flux interlocking unit; Wherein, when the output of described first flux locked loop reaches the first predetermined threshold value, described threshold detection unit exports the first reset signal; Described magnetic flux interlocking unit, when receiving described first reset signal, is relocked after being resetted by reset unit to the first flux locked loop again; Described data acquisition unit is collected described first flux locked loop and is compensated the first flux locked loop for locking working point from being reset to the flux change occurred in the Dead Time between relocking; And, when detecting after described first flux locked loop relocks and receive the second reset signal that described threshold detection unit exports because the output of the second flux locked loop reaches the second predetermined threshold value, described data acquisition unit controls to relock after described magnetic flux interlocking unit is resetted to described second flux locked loop unit by described reset unit again, and the flux change that described data acquisition unit collects the interior generation of Dead Time that described second flux locked loop is reset between locking compensates the second flux locked loop for locking working point.
Optionally, described first flux locked loop and the second flux locked loop are same circuits structure, and described circuit structure comprises: front-end amplifier, and it comprises: two input ends and the output terminal that connect SQUID and bias voltage source respectively; Integrator, its input end connects the output terminal of described front-end amplifier, and its output terminal is as the output terminal of flux locked loop; Tickler, is connected to the output terminal of described integrator through feedback resistance, be magnetically coupled to the SQUID that described front-end amplifier input end connects.
Optionally, described front-end amplifier, comprising: first order amplifier, and its negative input meets SQUID; First resistance, its two ends connect negative input and the output terminal of described first order amplifier respectively; Wherein, the positive pole of described first order amplifier connects the positive pole of described bias voltage source, the minus earth of described bias voltage source; Described integrator, comprising: second level amplifier, and its negative input is connected to the output terminal of described first order amplifier, the electrode input end ground connection of described second level amplifier; Electric capacity, two ends are connected to negative input and the output terminal of described second level amplifier respectively.
Optionally, described first predetermined threshold value comprises the first reference voltage level, and described second predetermined threshold value comprises the second reference voltage level; Described threshold detection unit, comprise: first threshold circuit, comprise: the first comparer and the second comparer, the negative input of described first comparer connects the electrode input end of the second comparer and is connected to the output terminal of the first flux locked loop, the electrode input end input of described first comparer has the first negative reference voltage level, the negative input input of described second comparer has the first positive reference voltage level, when being greater than the first reference voltage level with the absolute value of the output at described first flux locked loop, export the first reset signal; The output terminal of described first comparer and the second comparer is all connected to described data acquisition unit; Second Threshold circuit, comprise: the 3rd comparer and the 4th comparer, the negative input of described 3rd comparer connects the electrode input end of the 4th comparer and is connected to the output terminal of the second flux locked loop, the electrode input end input of described 3rd comparer has the second negative reference voltage level, the negative input input of described 4th comparer has the second positive reference voltage level, when being greater than the second reference voltage level with the absolute value of the output at described second flux locked loop, export the second reset signal; The output terminal of described 3rd comparer and the 4th comparer is all connected to described data acquisition unit.
Optionally, described threshold detection unit also comprises: the 3rd threshold circuit, comprise: the 5th comparer and the 6th comparer, the electrode input end of described 5th comparer connects the negative input of the 6th comparer and is connected to the output terminal of the first flux locked loop, the negative input input of described 5th comparer has the 3rd negative reference voltage level, the electrode input end input of described 6th comparer has the 3rd positive reference voltage level, when being less than the 3rd reference voltage level with the absolute value of the output at described first flux locked loop, exporting locking and represent signal.
Optionally, described reset unit comprises: the second reset switch being connected to the first reset switch in the first flux locked loop and being connected in the second flux locked loop; Described magnetic flux interlocking unit comprises: first or logical block, comprising: connect two input ends of the output terminal of described first comparer and the second comparer respectively and be connected to described first reset switch with the output terminal of output switching signal; Second or logical block, comprising: two input ends and the output terminal that connect the output terminal of described 3rd comparer and the 4th comparer respectively; First and logical block, comprising: three input ends of connection data collecting unit, the output terminal of the 5th comparer and the output terminal of the 6th comparer and an output terminal respectively; Second and logical block, comprising: connect respectively described second or logical block output terminal and first and logical block output terminal two input ends and be connected to described second reset switch with the output terminal of output switching signal.
Optionally, a described SQUID, comprising: the first superconducting loop and connect the first pick-up winding of described first superconducting loop; Described 2nd SQUID, be located at below a described SQUID, it comprises: the second superconducting loop alignd with described first superconducting loop and be connected described second superconducting loop and area be less than described first pick-up winding the second pick-up winding or without described second pick-up winding.
Optionally, the first tickler included by described first flux locked loop is positioned at described first pick-up winding farthest away from the edge of the first superconducting loop or corner; The second tickler included by described second flux locked loop is positioned at the center of described second superconducting loop.
For realizing above-mentioned target and other related objectives, the invention provides a kind of fluxon method of counting without Dead Time, apply as front fluxon counting assembly as described in any one, described method comprises: lock working point again after resetting to described first flux locked loop and the second flux locked loop; Another is in described locking working point state when described reset to make there is one in described first flux locked loop and the second flux locked loop, the flux locked loop collecting described reset, in the flux change being reset to the generation of the Dead Time between locking, supplies locking working point to compensate to the flux locked loop of described reset.
In sum, the invention provides a kind of fluxon counting assembly without Dead Time and method, working point is locked again after two flux locked loops of the SQUID connecting different sensitivity are respectively resetted, and another is in described locking working point state when described reset to utilize magnetic flux interlocking unit to make there is one in described two flux locked loops, the flux locked loop collecting described reset, in the flux change being reset to the generation of the Dead Time between locking, supplies locking working point to compensate to the flux locked loop of described reset.The invention provides a kind of fluxon counting assembly without Dead Time and method, not only by positive return in an orderly manner and the range relocking its sensing circuit of infinite expanding in the normal operation interval of SQUID, and the linearity improved in its whole range, and can effectively avoid traditional fluxon method of counting in Dead Time, there is the risk of working point jump.By optimizing structural design and the space layout of two different sensitivity SQUID, such as, adopt two-stage topologies to reduce the measuring error caused by channels crosstalk and magnetic gradient.
Accompanying drawing explanation
Fig. 1 is V-Φ curve and the working point schematic diagram thereof of existing SQUID.
Fig. 2 is the function structure chart of the fluxon counting assembly without Dead Time in one embodiment of the invention.
Fig. 3 is the topological structure of the SQUID in one embodiment of the invention.
Fig. 4 is the circuit theory diagrams of the fluxon counting assembly without Dead Time in one embodiment of the invention.
Fig. 5 is the working timing figure of fluxon counting embody rule in one embodiment of the invention.
Embodiment
Below by way of specific instantiation, embodiments of the present invention are described, those skilled in the art the content disclosed by this instructions can understand other advantages of the present invention and effect easily.The present invention can also be implemented or be applied by embodiments different in addition, and the every details in this instructions also can based on different viewpoints and application, carries out various modification or change not deviating under spirit of the present invention.It should be noted that, when not conflicting, the embodiment in the application and the feature in embodiment can combine mutually.
Superconducting quantum interference device (SQUID) is a kind of magnetic flux voltage converter built based on Josephson junction, have two kinds of equivalent mode of operations: voltage bias and current offset, wherein under current offset mode of operation, the output voltage V at SQUID two ends presents cyclical variation along with the increase of outside magnetic flux Φ, as shown in Figure 1, the V-Φ characteristic of visible SQUID is not linear, usually to need after noise matching by flux locked loop linearization to reach practical object.When adopting flux locked loop circuit working, need the bias of regulating circuit to offset the bias Voffset of SQUID two ends output voltage, thus make the working point of circuit be locked in the highest place of magnetic flux voltage converting sensitivity as far as possible, as shown in working point A, B, the C in Fig. 1, but be specifically locked in which working point then to need to determine according to conditions such as the flux field conversion coefficients of external magnetic field intensity and SQUID sensing circuit, because by the always relative quantity of the numerical value measured by FLL and SQUID, once losing lock, both cannot be connected by interpolation.
As shown in Figure 2, the invention provides a kind of fluxon counting assembly without Dead Time, comprising: two flux locked loops, connect two SQUID of different sensitivity correspondingly respectively, threshold detection unit, connects the output terminal of described two flux locked loops respectively, reset unit, accesses described two flux locked loops respectively, magnetic flux interlocking unit, is connected between described threshold detection unit and reset unit, data acquisition unit, connect the output terminal of described two flux locked loops, connect the output terminal of described threshold detection unit, and connect the input end of described magnetic flux interlocking unit, trigger after described reset unit resets to described two flux locked loops lock working point again for controlling magnetic flux interlocking unit, wherein, another is in described locking working point state when described reset one in described two flux locked loops, collect the flux locked loop of described reset in the flux change being reset to the generation of the Dead Time between locking, to compensate to the flux locked loop of described reset for locking working point.
As shown in Figure 3, a described SQUID, comprising: the first superconducting loop 2 and connect the first pick-up winding 1 of described first superconducting loop 2; Described 2nd SQUID, be located at below a described SQUID, and coplanar, it comprises: the second superconducting loop 3 alignd with described first superconducting loop 2 and be connected described second superconducting loop 3 and area be less than described first pick-up winding 1 the second pick-up winding 4 or without described second pick-up winding 4.In one embodiment, the first tickler L1 included by described first flux locked loop is positioned at described first pick-up winding 1 farthest away from the edge of the first superconducting loop or corner; The second tickler L2 included by described second flux locked loop is positioned at the center of described second superconducting loop 3.
Concrete, high sensitivity SQUIDU1 (i.e. a SQUID) adopts the project organization of band pick-up winding (Pick-up), form primarily of the first pick-up winding 1 and the first superconducting loop 2, the tickler L1 building high sensitivity SQUIDU1 sensing circuit is then positioned at the upper left corner of the first pick-up winding 1 to increase the distance of the first superconducting loop 2 and tickler L1, and then reduces the crosstalk between high sensitivity SQUIDU1 and muting sensitivity SQUIDU2; Muting sensitivity SQUIDU2 then needs to adopt the very little or project organization not with pick-up winding of pick-up winding, namely in Fig. 3, the second pick-up winding 4 can be canceled according to the designing requirement of sensitivity, if wherein without the muting sensitivity SQUIDU2 of pick-up winding, to be directly made up of the second superconducting loop 3, the tickler L2 building muting sensitivity SQUIDU2 sensing circuit is then positioned at the center of the second superconducting loop 3 to increase feedback factor.In addition, for reducing the crosstalk between high sensitivity SQUIDU1 and muting sensitivity SQUIDU2 two passages further, magnetic field gradient profile both simultaneously reducing between measuring position, adopt plane figure as shown in Figure 3, namely muting sensitivity SQUIDU2 is positioned at immediately below high sensitivity SQUIDU1, and away from the tickler L1 of high sensitivity SQUIDU1.In the present embodiment, the flux field conversion coefficient of high sensitivity SQUIDU1 is 1.2nT/ Φ 0, and the flux field conversion coefficient of muting sensitivity SQUIDU2 is 400nT/ Φ 0;
Refer to Fig. 4, below illustrate that the present invention realizes without the physical circuit of the fluxon counting assembly of Dead Time.
In one embodiment, described first flux locked loop and the second flux locked loop are same circuits structure, and described circuit structure comprises: front-end amplifier, and it comprises: two input ends and the output terminal that connect SQUID and bias voltage source respectively; Integrator, its input end connects the output terminal of described front-end amplifier, and its output terminal is as the output terminal of flux locked loop; Tickler, is connected to the output terminal of described integrator through feedback resistance, be magnetically coupled to the SQUID that described front-end amplifier input end connects.In one embodiment, described front-end amplifier, comprising: first order amplifier, and its negative input meets SQUID; First resistance, its two ends connect negative input and the output terminal of described first order amplifier respectively; Wherein, the positive pole of described first order amplifier connects the positive pole of described bias voltage source, the minus earth of described bias voltage source; Described integrator, comprising: second level amplifier, and its negative input is connected to the output terminal of described first order amplifier, the electrode input end ground connection of described second level amplifier; Electric capacity, two ends are connected to negative input and the output terminal of described second level amplifier respectively.
Concrete, flux locked loop for reading high sensitivity SQUIDU1 comprises the front-end amplifier, bias voltage source Vb1, the integrator be made up of operational amplifier IC2 and electric capacity C1, the feedback resistance Rf1 and tickler L1 that are made up of operational amplifier IC1 and resistance Rg1, and the flux locked loop for reading muting sensitivity SQUIDU2 then comprises the front-end amplifier, bias voltage source Vb2, the integrator be made up of operational amplifier IC7 and electric capacity C2, the feedback resistance Rf2 and tickler L2 that are made up of operational amplifier IC6 and resistance Rg2.
In one embodiment, described first predetermined threshold value comprises the first reference voltage level (Vref1), and described second predetermined threshold value comprises the second reference voltage level (Vref2), described threshold detection unit, comprise: first threshold circuit, comprise: the first comparer (IC3) and the second comparer (IC4), the negative input of described first comparer (IC3) connects the electrode input end of the second comparer (IC4) and is connected to the output terminal of the first flux locked loop, the electrode input end input of described first comparer (IC3) has negative the first reference voltage level (Vref1-), and the negative input input of described second comparer (IC4) has positive the first reference voltage level (Vref1+), the output terminal of described first comparer (IC3) and the second comparer (IC4) is all connected to described data acquisition unit, Second Threshold circuit, comprise: the 3rd comparer (IC8) and the 4th comparer (IC9), the negative input of described 3rd comparer (IC8) connects the electrode input end of the 4th comparer (IC9) and is connected to the output terminal of the second flux locked loop, the electrode input end input of described 3rd comparer (IC8) has negative the second reference voltage level (Vref2-), and the negative input input of described 4th comparer (IC9) has positive the second reference voltage level (Vref2+), the output terminal of described 3rd comparer (IC8) and the 4th comparer (IC9) is all connected to described data acquisition unit, in one embodiment, described threshold detection unit also comprises: the 3rd threshold circuit, comprise: the 5th comparer (IC11) and the 6th comparer (IC12), the electrode input end of described 5th comparer (IC11) connects the negative input of the 6th comparer (IC12) and is connected to the output terminal of the first flux locked loop, the negative input input of described 5th comparer (IC11) has the 3rd negative reference voltage level (Vref3-), the electrode input end input of described 6th comparer (IC12) has the 3rd positive reference voltage level (Vref3+).
In one embodiment, described reset unit comprises: the second reset switch (S2) being connected to the first reset switch (S1) in the first flux locked loop and being connected in the second flux locked loop, such as field effect transistor (MOS) switch; Described magnetic flux interlocking unit comprises: first or logical block (IC5), comprising: connect two input ends of the output terminal of described first comparer (IC3) and the second comparer (IC4) respectively and be connected to described first reset switch (S1) with the output terminal of output switching signal; Second or logical block (IC13), comprising: two input ends and the output terminal that connect the output terminal of described 3rd comparer (IC8) and the 4th comparer (IC9) respectively; First with logical block (IC14), comprising: respectively three input ends of connection data collecting unit, the output terminal of the 5th comparer (IC11) and the output terminal of the 6th comparer (IC12) and an output terminal; Second with logical block (IC10), comprising: connect respectively described second or logical block (IC13) output terminal and first and logical block (IC14) output terminal two input ends and be connected to described second reset switch (S2) with the output terminal of output switching signal.
In one embodiment, first or logical block (IC5), comprising: connect two input ends of the output terminal of described first comparer (IC3) and the second comparer (IC4) respectively and be connected to described first reset switch (S1) with the output terminal of output switching signal; Second or logical block (IC13), comprising: two input ends and the output terminal that connect the output terminal of described 3rd comparer (IC8) and the 4th comparer (IC9) respectively; First with logical block (IC14), comprising: respectively three input ends of connection data collecting unit, the output terminal of the 5th comparer (IC11) and the output terminal of the 6th comparer (IC12) and an output terminal; Second with logical block (IC10), comprising: connect respectively described second or logical block (IC13) output terminal and first and logical block (IC14) output terminal two input ends and be connected to described second reset switch (S2) with the output terminal of output switching signal.
Specifically, threshold dector is made up of two comparers, be used for judging whether the output of flux locked loop exceeds the threshold value of setting, as the threshold value Vref1 set in Fig. 4, Vref2 and Vref3, wherein high sensitivity SQUIDU1 magnetic flux counting channel comprises two threshold dectors, setting threshold value is Vref1 (Vref1+, Vref1-is the positive and negative values of Vref1 respectively) detecting device for judging whether the sensing circuit of reset high sensitivity SQUIDU1, the output of its comparer must be input in the Digital I/O in data acquisition unit, and pass through or gate logic unit IC5 gauge tap S1 generation reset signal, setting threshold value is that the detecting device of Vref3 is then for generating the locking signal of muting sensitivity SQUIDU2 magnetic flux counting channel reset, namely when the absolute value of high sensitivity SQUIDU1 magnetic flux counting channel output values Vo1 is less than setting threshold value Vref3, muting sensitivity SQUIDU2 magnetic flux counting channel can reset, it is the threshold dector of Vref2 that muting sensitivity SQUIDU2 magnetic flux counting channel then only comprises a setting threshold value, for judging whether its sensing circuit that resets, the output of its comparer also must be input in the Digital I/O in data acquisition unit, and by or gate logic unit IC13, with gate logic unit IC10 and IC14 gauge tap S2 produce reset signal, the field effect transistor S1 that reset unit is exceedingly fast by switching speed and S2 is formed, the integrator be used in reset SQUID sensing circuit flux locked loop, magnetic flux counting interlocking unit then exported by Digital I/O of data acquisition unit and two form with gate logic unit IC10, IC14, the flux locked loop being used to provide two different sensitivity interlocks, wherein the Digital I/O of this passage of data acquisition unit exports is true under normal circumstances, when muting sensitivity SQUIDU2 magnetic flux counting channel reset, it is false for then resetting that it exports, and time delay 2 doubly to high sensitivity SQUIDU1 sensing circuit reset and after the time relocked again set be true, data acquisition unit is then made up of the CompactRIO monitoring platform based on Embedded America NI company, NI9239 analog-to-digital conversion module wherein in CompactRIO monitoring platform be used for collection two passages flux locked loop export, NI9401 digital I/O module is then used for gathering threshold dector, and provides the enable signal that the flux locked loop of two different sensitivity interlocks.
For setting forth the workflow without Dead Time fluxon counting of the present invention simply, assuming that extraneous tested magnetic field monotone increasing in time, and be 200mV/ Φ 0 and 50mV/ Φ 0 by the magnetic flux voltage conversion coefficient that feedback resistance Rf1 and feedback resistance Rf2 arrange high sensitivity SQUID sensing circuit and muting sensitivity SQUID sensing circuit respectively, thus the field voltage conversion coefficient that can calculate high sensitivity and muting sensitivity SQUID sensing circuit in the present embodiment is 6nT/V and 8uT/V, the threshold value simultaneously setting threshold dector is the integral multiple of respective magnetic flux voltage conversion coefficient, namely setting Vref1 and Vref2 is 8V, Vref3 is then 5% of high sensitivity SQUID sensing circuit range, i.e. 0.5V.Arrange according to above-mentioned supposition and condition of work, without the work schedule such as shown in Fig. 5 of Dead Time fluxon counting, visible, when the output absolute value of high sensitivity SQUIDU1 sensing circuit exceedes the threshold value Vref1 of setting, at once it resetted and relock, and in Dead Time t1, if when detecting that external magnetic field fluctuation exceedes one Φ 0 by the sensing circuit of muting sensitivity SQUIDU2 (described flux change can be the jump between multiple discrete flux value), then Φ 0 compensation of external magnetic field fluctuation correspondence must be gone back when magnetic flux count, and the output absolute value of muting sensitivity SQUIDU1 sensing circuit is when exceeding the threshold value Vref2 of setting, can not reset to it at once, must judge whether the output absolute value of high sensitivity SQUIDU1 sensing circuit is less than the threshold value Vref3 of setting, even if when above-mentioned two conditions all meet, if data acquisition unit detects that high sensitivity SQUIDU1 sensing circuit resets, could reset to muting sensitivity SQUIDU1 sensing circuit and relock after then needing t3 time delay, so by positive return in an orderly manner and again quick lock in make the two-way SQUID sensing circuit in fluxon counting assembly have a road to lock all the time, thus when a road is in Dead Time, utilize the test data on another road to know the jump situation of its working point wherein, and then eliminate the Dead Time existed in traditional fluxon counting on the whole, and can in the normal operation interval of SQUID the range of its sensing circuit of infinite expanding.Wherein t1 is that high sensitivity SQUIDU1 sensing circuit is from resetting to the Dead Time relocked, t2 be muting sensitivity SQUIDU2 sensing circuit from resetting to the Dead Time relocked, t3 is the delay time that data acquisition unit interlocks for two different sensitivity flux locked loops.
From the foregoing, the present invention also can provide a kind of fluxon method of counting without Dead Time, apply as front fluxon counting assembly as described in any one, described method comprises: lock working point again after resetting to described first flux locked loop and the second flux locked loop; Another is in described locking working point state when described reset to make there is one in described first flux locked loop and the second flux locked loop, the flux locked loop collecting described reset, in the flux change being reset to the generation of the Dead Time between locking, supplies locking working point to compensate to the flux locked loop of described reset.
In sum, the invention provides a kind of fluxon counting assembly without Dead Time and method, working point is locked again after two flux locked loops of the SQUID connecting different sensitivity are respectively resetted, and another is in described locking working point state when described reset to utilize magnetic flux interlocking unit to make there is one in described two flux locked loops, the flux locked loop collecting described reset, in the flux change being reset to the generation of the Dead Time between locking, supplies locking working point to compensate to the flux locked loop of described reset.The invention provides a kind of fluxon counting assembly without Dead Time and method, not only by positive return in an orderly manner and the range relocking its sensing circuit of infinite expanding in the normal operation interval of SQUID, and the linearity improved in its whole range, and can effectively avoid traditional fluxon method of counting in Dead Time, there is the risk of working point jump.By optimizing structural design and the space layout of two different sensitivity SQUID, such as, adopt two-stage topologies to reduce the measuring error caused by channels crosstalk and magnetic gradient.
Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not for limiting the present invention.Any person skilled in the art scholar all without prejudice under spirit of the present invention and category, can modify above-described embodiment or changes.Therefore, such as have in art usually know the knowledgeable do not depart from complete under disclosed spirit and technological thought all equivalence modify or change, must be contained by claim of the present invention.
Claims (9)
1., without a fluxon counting assembly for Dead Time, it is characterized in that, comprising:
First flux locked loop and the second flux locked loop, connecting respectively is a highly sensitive SQUID and relative the 2nd SQUID for muting sensitivity relatively;
Threshold detection unit, connects the output terminal of described first flux locked loop and the second flux locked loop respectively;
Reset unit, accesses described first flux locked loop and the second flux locked loop respectively;
Magnetic flux interlocking unit, is connected between described threshold detection unit and reset unit; ;
Data acquisition unit, the output terminal connecting described first flux locked loop and the second flux locked loop, connect described threshold detection unit output terminal and connect the input end of described magnetic flux interlocking unit;
Wherein, when the output of described first flux locked loop reaches the first predetermined threshold value, described threshold detection unit exports the first reset signal; Described magnetic flux interlocking unit, when receiving described first reset signal, is relocked after being resetted by reset unit to the first flux locked loop again; Described data acquisition unit is collected described first flux locked loop and is compensated the first flux locked loop for locking working point from being reset to the flux change occurred in the Dead Time between relocking;
And, when detecting after described first flux locked loop relocks and receive the second reset signal that described threshold detection unit exports because the output of the second flux locked loop reaches the second predetermined threshold value, described data acquisition unit controls to relock after described magnetic flux interlocking unit is resetted to described second flux locked loop unit by described reset unit again, and the flux change that described data acquisition unit collects the interior generation of Dead Time that described second flux locked loop is reset between locking compensates the second flux locked loop for locking working point.
2. the fluxon counting assembly without Dead Time according to claim 1, is characterized in that, described first flux locked loop and the second flux locked loop are same circuits structure, and described circuit structure comprises:
Front-end amplifier, it comprises: two input ends and the output terminal that connect SQUID and bias voltage source respectively;
Integrator, its input end connects the output terminal of described front-end amplifier, and its output terminal is as the output terminal of flux locked loop;
Tickler, is connected to the output terminal of described integrator through feedback resistance, be magnetically coupled to the SQUID that described front-end amplifier input end connects.
3. the fluxon counting assembly without Dead Time according to claim 2, is characterized in that,
Described front-end amplifier, comprising:
First order amplifier, its negative input meets SQUID;
First resistance, its two ends connect negative input and the output terminal of described first order amplifier respectively;
Wherein, the positive pole of described first order amplifier connects the positive pole of described bias voltage source, the minus earth of described bias voltage source;
Described integrator, comprising:
Second level amplifier, its negative input is connected to the output terminal of described first order amplifier, the electrode input end ground connection of described second level amplifier;
Electric capacity, two ends are connected to negative input and the output terminal of described second level amplifier respectively.
4. the fluxon counting assembly without Dead Time according to claim 1, is characterized in that, described first predetermined threshold value comprises the first reference voltage level, and described second predetermined threshold value comprises the second reference voltage level; Described threshold detection unit, comprising:
First threshold circuit, comprise: the first comparer and the second comparer, the negative input of described first comparer connects the electrode input end of the second comparer and is connected to the output terminal of the first flux locked loop, the electrode input end input of described first comparer has the first negative reference voltage level, the negative input input of described second comparer has the first positive reference voltage level, when being greater than the first reference voltage level with the absolute value of the output at described first flux locked loop, export the first reset signal; The output terminal of described first comparer and the second comparer is all connected to described data acquisition unit;
Second Threshold circuit, comprise: the 3rd comparer and the 4th comparer, the negative input of described 3rd comparer connects the electrode input end of the 4th comparer and is connected to the output terminal of the second flux locked loop, the electrode input end input of described 3rd comparer has the second negative reference voltage level, the negative input input of described 4th comparer has the second positive reference voltage level, when being greater than the second reference voltage level with the absolute value of the output at described second flux locked loop, export the second reset signal; The output terminal of described 3rd comparer and the 4th comparer is all connected to described data acquisition unit.
5. the fluxon counting assembly without Dead Time according to claim 4, it is characterized in that, described threshold detection unit also comprises: the 3rd threshold circuit, it comprises: the 5th comparer and the 6th comparer, the electrode input end of described 5th comparer connects the negative input of the 6th comparer and is connected to the output terminal of the first flux locked loop, the negative input input of described 5th comparer has the 3rd negative reference voltage level, the electrode input end input of described 6th comparer has the 3rd positive reference voltage level, when being less than the 3rd reference voltage level with the absolute value of the output at described first flux locked loop, export locking and represent signal.
6. the fluxon counting assembly without Dead Time according to claim 5, it is characterized in that, described reset unit comprises: the second reset switch being connected to the first reset switch in the first flux locked loop and being connected in the second flux locked loop; Described magnetic flux interlocking unit comprises:
First or logical block, comprising: connect two input ends of the output terminal of described first comparer and the second comparer respectively and be connected to described first reset switch with the output terminal of output switching signal;
Second or logical block, comprising: two input ends and the output terminal that connect the output terminal of described 3rd comparer and the 4th comparer respectively;
First and logical block, comprising: three input ends of connection data collecting unit, the output terminal of the 5th comparer and the output terminal of the 6th comparer and an output terminal respectively;
Second and logical block, comprising: connect respectively described second or logical block output terminal and first and logical block output terminal two input ends and be connected to described second reset switch with the output terminal of output switching signal.
7. the fluxon counting assembly without Dead Time according to claim 2, is characterized in that,
A described SQUID, comprising: the first superconducting loop and connect the first pick-up winding of described first superconducting loop;
Described 2nd SQUID, coplanar with a SQUID, and be located at below a described SQUID, it comprises: the second superconducting loop alignd with described first superconducting loop and be connected described second superconducting loop and area be less than described first pick-up winding the second pick-up winding or without described second pick-up winding.
8. the fluxon counting assembly without Dead Time according to claim 7, is characterized in that, the first tickler included by described first flux locked loop is positioned at described first pick-up winding farthest away from the edge of the first superconducting loop or corner; The second tickler included by described second flux locked loop is positioned at the center of described second superconducting loop.
9. without a fluxon method of counting for Dead Time, it is characterized in that, the fluxon counting assembly of application according to any one of claim 1 to 8, described method comprises:
Working point is locked again after described first flux locked loop and the second flux locked loop are resetted;
Another is in described locking working point state when described reset to make there is one in described first flux locked loop and the second flux locked loop, the flux change that the flux locked loop collecting described reset is being reset to the Dead Time between locking and occurs, with judge the flux locked loop of described reset relock after working point.
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