JPH0638103B2 - DC type SQUID device - Google Patents
DC type SQUID deviceInfo
- Publication number
- JPH0638103B2 JPH0638103B2 JP62246860A JP24686087A JPH0638103B2 JP H0638103 B2 JPH0638103 B2 JP H0638103B2 JP 62246860 A JP62246860 A JP 62246860A JP 24686087 A JP24686087 A JP 24686087A JP H0638103 B2 JPH0638103 B2 JP H0638103B2
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- magnetic flux
- frequency
- bias
- squid
- voltage
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Description
【発明の詳細な説明】 ［発明の目的］ （産業上の利用分野） 本発明は、直流型ＳＱＵＩＤ（超伝導量子干渉素子）装
置に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a direct current SQUID (superconducting quantum interference device) device.
（従来の技術） 微小磁束（磁界）を検出するためのものとして、ＳＱＵ
ＩＤ（Superconducting Quantum Interference DEVIC
E：超伝導量子干渉素子）が知られている。これは第１
０図に示すようにジョセフソン素子を２個含む超伝導ル
ープからなり、素子を一定の直流電流でバイアスすると
き、端子電圧Ｖがループを貫く磁束φにより、磁束量子
φ０（＝２×１０-15Ｗb ）単位で変化する特性をもつ
ことを利用して微小磁界を計測するものである。(Prior Art) SQU is used to detect a minute magnetic flux (magnetic field).
ID (Superconducting Quantum Interference DEVIC)
E: superconducting quantum interference device) is known. This is the first
As shown in Fig. 0, it is composed of a superconducting loop including two Josephson devices, and when the device is biased with a constant direct current, the terminal voltage V causes a magnetic flux quantum φ 0 (= 2 × 10 It measures a very small magnetic field by utilizing the fact that it has the property of changing in units of -15 Wb).
ところで、前記バイアスに交流矩形波を用いて、磁束変
調と併用してＳＱＵＩＤを制御する公知例（米国特許第
4,389,612）がある。これを第１１図のタイムチャート
を参照して説明する。By the way, a known example of controlling an SQUID in combination with magnetic flux modulation by using an AC rectangular wave as the bias (US Patent No.
4,389,612). This will be described with reference to the time chart of FIG.
先ずバイアスとして＋Ｉ０と−Ｉ０の間を変化する矩形
波電流Ｉ０を用いると共に、このバイアス電流Ｉ０の周
波数ｆb の１／４の周波数ｆm をもつ交流磁束φm をＳ
ＱＵＩＤのループに加えて端子電圧を変調した後、それ
を増幅して増幅変調電圧Ｖ０を得る。この変調電圧の△
Ｖに相当する周波数成分電圧Ｖｆm を得た後、このＶｆ
m から参照信号ＶＲを生成し、この参照信号ＶＲを復調
器に印加することによって入力磁場φの変化に対応した
復調信号Ｖd(φ)を得るようにしている。First, a rectangular wave current I 0 changing between + I 0 and -I 0 is used as a bias, and an AC magnetic flux φm having a frequency fm that is ¼ of the frequency fb of the bias current I 0 is used as S.
After the terminal voltage is modulated in addition to the loop of the QUID, it is amplified to obtain the amplified modulation voltage V 0 . △ of this modulation voltage
After obtaining the frequency component voltage Vfm corresponding to V, this Vf
A reference signal V R is generated from m, and this reference signal V R is applied to a demodulator to obtain a demodulation signal Vd (φ) corresponding to a change in the input magnetic field φ.
この公知例によれば、前記交流バイアスにより、熱的な
電流変動雑音を除去することができるというものであ
る。According to this known example, it is possible to remove thermal current fluctuation noise by the AC bias.
（発明が解決しようとする問題点） しかしながら前記公知例では、温度変化に基づく電流変
動ノイズの除去、すなわち、ジョセフソン素子に含まれ
る抵抗が発生する熱雑音の除去には効果があるものの、
ＳＱＵＩＤの端子電圧の変動に基づく雑音（特に低周波
雑音）を除去することはできない。(Problems to be Solved by the Invention) However, in the above-mentioned known example, although it is effective in removing the current fluctuation noise based on the temperature change, that is, in removing the thermal noise generated by the resistance included in the Josephson element,
It is not possible to remove noise (especially low frequency noise) due to fluctuations in the terminal voltage of the SQUID.
この問題を第１２図を参照して説明する。上記公知例で
は正と負の参照電圧Ｖｒ＋とＶｒ−を変調磁束φｍの
「１」，「０」の周期に対応して切換えることによって
参照信号ＶＲを得ている。このように変調磁束φｍの変
化に対応して参照信号を反転させているため、変調磁束
の周波数よりも高い周波数のバイアス電流Ｉｏの正負に
よって変化する磁束変動ノイズ（△Ｖ）を除去すること
はできない。This problem will be described with reference to FIG. In the above known example positive and negative reference voltage Vr + and Vr - "1" of the modulation magnetic flux [phi] m, to obtain a reference signal V R by switching in response to the period of "0". Since the reference signal is inverted corresponding to the change in the modulation magnetic flux φm in this way, it is not possible to remove the magnetic flux fluctuation noise (ΔV) that changes depending on the positive / negative of the bias current Io having a frequency higher than the frequency of the modulation magnetic flux. Can not.
本発明は前記事情に鑑みてなされたものであり、熱雑音
のみでなく、端子電圧変動に基づく雑音をも除去するこ
とのできるＳＱＵＩＤ装置を提供することを目的とする
ものである。The present invention has been made in view of the above circumstances, and an object thereof is to provide an SQUID device capable of removing not only thermal noise but also noise due to terminal voltage fluctuations.
［発明の構成］ （問題点を解決するための手段） 前記問題を解決するために本発明は直流型ＳＱＵＩＤ
と、これを駆動制御する手段とからなる直流型ＳＱＵＩ
Ｄ装置において、前記直流型ＳＱＵＩＤに周波数ｆb を
有する正，負の交番バイアスを与えるバイアス電流供給
手段と、このバイアス電流の周波数ｆb より高い周波数
であって、この周波数ｆb の整数倍の周波数ｆm の交流
磁束を与えることにより前記直流型ＳＱＵＩＤの電圧を
変調する変調磁束供給手段と、前記変調電圧を復調し、
この復調電圧について前記正，負バイアス時のそれぞれ
の電圧を参照信号として連続波形を作成する復調手段
と、この復調信号を磁束として前記直流型ＳＱＵＩＤに
フィードバックする手段とを有するものである。[Structure of the Invention] (Means for Solving Problems) In order to solve the above problems, the present invention is directed to a DC SQUID.
And a DC-type SQUI comprising a drive control means
In the D device, a bias current supply means for giving a positive and negative alternating bias having a frequency fb to the DC type SQUID, and a frequency higher than the frequency fb of the bias current and an integral multiple of the frequency fb. Modulating magnetic flux supply means for modulating the voltage of the DC type SQUID by giving an alternating magnetic flux, and demodulating the modulating voltage,
The demodulation voltage has demodulation means for creating a continuous waveform using the positive and negative bias voltages as reference signals, and means for feeding back the demodulation signals as magnetic flux to the DC type SQUID.
（作 用） 変調磁束に含まれる雑音成分が、それよりも低い周波数
のバイアス電流の変化の各周期内に取り込まれ、最終的
に復調電圧波形に表わるので、容易に除去することがで
きる。(Operation) The noise component contained in the modulation magnetic flux is captured in each cycle of the change of the bias current of a frequency lower than that, and finally appears in the demodulation voltage waveform, so that it can be easily removed.
（実施例） 以下実施例により本発明を具体的に説明する。(Example) Hereinafter, the present invention will be specifically described with reference to examples.
同図において１は発振器であり、２は発振器の発振出力
に基づいて正と負に交互に変化するバイアス電流Ｉb
（周波数ｆb）を発生するバイアス電流発生回路であ
り、３は変調磁束φm(t)を発生する変調磁束発生回路で
ある。この変調磁束φm(t)の周波数ｆm は前記バイアス
電流の周波数ｆb の４倍（ｆm ＝４ｆb）としてある。
前記バイアス電流Ｉb は、ＳＱＵＩＤの出力端を通るこ
とにより変調電圧Ｖm(t)を作り、交流増幅回路４に入力
される。前記変調磁束信号φm(t)は正バイアス及び負バ
イアスの各位相調整回路５，６に印加されると共に、Ｓ
ＱＵＩＤの変調コイルＬに印加されている。これら正，
負バイアス調整回路５，６の出力はそれぞれ参照信号切
換手段７のＶｒ＋端子，Ｖｒ−端子に印加されている。
前記参照信号切換手段７は前記バイアス電流Ｉb の正，
負切替タイミングに基づいて制御されるようになってい
る。この参照信号ＶＲは復調回路８に入力される。復調
回路８では前記交流増幅器４からの周波数ｆm 成分の電
圧Ｖｆm を前記参照信号ＶＲとの関係で復調し、復調電
圧Ｖｄ（φ）を出力する。この復調電圧Ｖd （φ）は積
分器９で積分されて出力ＯＵＴとなると共に電圧／電流
変換器１０によって電流変換されてフィードバック電流
として前記変調コイルＬに供給される。In the figure, 1 is an oscillator, and 2 is a bias current Ib that alternately changes between positive and negative based on the oscillation output of the oscillator.
A bias current generation circuit for generating (frequency fb), and a modulation magnetic flux generation circuit 3 for generating a modulation magnetic flux φm (t). The frequency fm of the modulation magnetic flux φm (t) is set to be four times the frequency fb of the bias current (fm = 4fb).
The bias current Ib makes a modulation voltage Vm (t) by passing through the output terminal of the SQUID, and is input to the AC amplifier circuit 4. The modulated magnetic flux signal φm (t) is applied to the positive bias and negative bias phase adjustment circuits 5 and 6, and S
It is applied to the modulation coil L of the QUID. These positive,
The outputs of the negative bias adjusting circuits 5 and 6 are applied to the Vr + terminal and Vr − terminal of the reference signal switching means 7, respectively.
The reference signal switching means 7 controls the positive current of the bias current Ib,
The control is performed based on the negative switching timing. The reference signal V R is inputted to the demodulation circuit 8. A voltage Vfm frequency fm component from the AC amplifier 4 The demodulation circuit 8 demodulates in relation to the reference signal V R, and outputs a demodulated voltage Vd (phi). The demodulated voltage Vd (φ) is integrated by the integrator 9 to become the output OUT, and the current is converted by the voltage / current converter 10 to be supplied to the modulation coil L as a feedback current.
次に第２図のタイムチャートをも参照して前記装置の動
作を説明する。Next, the operation of the apparatus will be described with reference to the time chart of FIG.
変調磁束発生回路３から周波数ｆm の交流磁束φｍが発
生し、これが変調コイルＬを介してＳＱＵＩＤのループ
に印加され、端子電圧を交流化（変調）する。An AC magnetic flux φm having a frequency fm is generated from the modulation magnetic flux generating circuit 3 and is applied to the SQUID loop via the modulation coil L to AC-modulate (modulate) the terminal voltage.
上述の磁束変調を行ないながら変調周波数ｆm より低い
周波数ｆb(ｆm/n:nは整数）でバイアス電流を正（＋Ｉ
b）と負（−ＩB）との間で交番させる。この実施例では
ｆb ＝ｆm/４である。この結果、第３図にも示すように
正バイアスに対する変調電圧Ｖｍ+(t)と負バイアスに対
する変調電圧Ｖｍ-(t)が周期１／５b で交代する波形が
得られる（第２図中のＶm(t)のＡ，Ｂ，Ｃ，Ｄと第３図
のＡ，Ｂ，Ｃ，Ｄが対応する）。While performing the above magnetic flux modulation, the bias current is positive (+ I) at a frequency fb (fm / n: n is an integer) lower than the modulation frequency fm.
Alternate between b) and negative (-IB). In this embodiment, fb = fm / 4. As a result, as shown in FIG. 3, a waveform in which the modulation voltage Vm + (t) for the positive bias and the modulation voltage Vm − (t) for the negative bias alternate in the cycle 1 / 5b is obtained (in FIG. 2). A, B, C and D of Vm (t) correspond to A, B, C and D of FIG. 3).
次に交流増幅回路４で前記変調電圧Ｖm(t)のｆm 成分の
みが連続するような増幅信号Ｖｆm(t)が得られる。Next, the AC amplifier circuit 4 obtains an amplified signal Vfm (t) in which only the fm component of the modulation voltage Vm (t) is continuous.
そして、この信号Ｖｆm(t)は、変調磁束φm(t)を別々に
位相調整して得られた２つの参照信号Ｖｒ＋(t) とＶｒ
−(t) により交互に復調され、連続した復調電圧Ｖd と
なる。この信号Ｖd の低周波数若しくは直流成分はＳＱ
ＵＩＤの端子電圧Ｖ（φ）と同様に磁束φにより周期的
に変化する特性Ｖd （φ）をもっている。This signal Vfm (t) has two reference signals Vr + (t) and Vr obtained by separately adjusting the phases of the modulation magnetic flux φm (t).
- demodulated alternately by (t), the continuous demodulation voltage Vd. The low frequency or DC component of this signal Vd is SQ
Like the terminal voltage V (φ) of the UID, it has a characteristic Vd (φ) that changes periodically with the magnetic flux φ.
復調電圧Ｖd （φ）は積分器９（低域フィネルタでもよ
い）によりｆm やｆd 成分が除去された後、電流に変換
され、変調コイルＬにより磁束としてＳＱＵＩＤにフィ
ードバックされる。この結果ＳＱＵＩＤループ内の磁束
は一定に保たれフィードバック電流は信号磁束φに比例
した出力信号となる。The demodulation voltage Vd (φ) is converted into a current after the fm and fd components are removed by the integrator 9 (may be a low frequency finnelter), and is fed back to the SQUID as a magnetic flux by the modulation coil L. As a result, the magnetic flux in the SQUID loop is kept constant and the feedback current becomes an output signal proportional to the signal magnetic flux φ.
次に第４図乃至第７図をも参照して雑音除去の原理につ
いて詳述する。Next, the principle of noise removal will be described in detail with reference to FIGS. 4 to 7.
直流ＳＱＵＩＤの雑音源には複数の種類があり、ジョセ
フソン素子に含まれる抵抗が発生する熱雑音の他に見か
け上ＳＱＵＩＤの端子電圧Ｖが変動するような雑音があ
る。ＶはＳＱＵＩＤループを貫く磁束φの関数であるの
でＶの変動はＶ−φ特性におけるＶ（φ）の変動でもあ
る。そこで先ずＶ（φ）の変動として、φは変化せずに
Ｖのみが変動するような場合についてみると、第４図に
示すように変調磁束φm(t)により生ずる変調電圧Ｖm(t)
の波形には変化がない。従ってこのような雑音は前記磁
束変調を施した段階で自動的に除去されることとなる。There are a plurality of types of DC SQUID noise sources, and in addition to thermal noise generated by the resistance included in the Josephson element, there is apparently noise in which the SQUID terminal voltage V fluctuates. Since V is a function of the magnetic flux φ passing through the SQUID loop, the fluctuation of V is also the fluctuation of V (φ) in the V-φ characteristic. Therefore, first of all, as a variation of V (φ), when φ is not varied and only V is varied, the modulation voltage Vm (t) generated by the modulation magnetic flux φm (t) as shown in FIG.
There is no change in the waveform of. Therefore, such noise is automatically removed when the magnetic flux modulation is performed.
次にＶ−φ特性においてφを変動させるような雑音につ
いてみると、正バイアス時と負バイアス時とにおいて、
第５図のδφと−δφのように、互に逆方向に変動する
雑音と、第６図のように同一方向に変動するような雑音
の２種類がある。このような雑音のうち第６図に示すよ
うな雑音は、ＳＱＵＩＤのループ内にδφの外部磁束が
入ったことと全く等価となるので信号と何ら変るところ
はなく、除去すべき手段は全くない。Next, regarding noise that causes φ to fluctuate in the V-φ characteristic, when positive bias is applied and when negative bias is applied,
There are two types of noise, such as δφ and −δφ in FIG. 5, that fluctuate in opposite directions, and noise that fluctuates in the same direction as in FIG. Of these noises, the noise shown in FIG. 6 is completely equivalent to the external magnetic flux of δφ entering the SQUID loop, so there is no difference from the signal and there is no means to remove it. .
しかし、第５図に示すような雑音は、変調磁束φm(t)を
与え、それによって得られる変調電圧Ｖm(t)を考える
と、第７図に示すようにδφと−δφで生ずる。Ｖm(t)
とＶm(t)の成分は大きさも極性も等しいことが分る。こ
れに対し、信号磁束が加わるときは正バイアス，負バイ
アスいずれのバイアス時も同じ向きの変動δφとして働
くため、変調電圧Ｖｍ+(t) とＶｍ-(t) は大きさが等し
く極正が逆となる。次にＶm(t)を復調するとき、別々の
参照信号を用いて交互に復調を行ない、負バイアス時に
は復調電圧の極性が反転するようにする。（あるいは正
バイアス時の反転）。その結果復調信号Ｖd においては
δφと−δφで変動するような雑音は相殺され、バイア
スの方向によらずδφで変化するような磁束信号のみが
残る。この復調信号に比例するような磁束をＳＱＵＩＤ
のループにフィードバックするとＳＱＵＩＤは一定の磁
束状態にロックされ、フィードバック電流が信号磁束に
比例する出力となる。この出力においては、Ｖ（φ）特
性に変動を与えるような前述の３種類の雑音のうち、第
６図に示した雑音を除く他の雑音は除去されるのでＳＱ
ＵＩＤ装置の低雑音化が図れる。However, the noise as shown in FIG. 5 is generated by δφ and −δφ as shown in FIG. 7 when the modulation magnetic flux φm (t) is given and the modulation voltage Vm (t) obtained thereby is considered. Vm (t)
It can be seen that the components of and Vm (t) have the same magnitude and polarity. On the other hand, when a signal magnetic flux is applied, it acts as a fluctuation δφ in the same direction in both positive bias and negative bias, so that the modulation voltages Vm + (t) and Vm − (t) have the same magnitude and are of positive polarity. The opposite is true. Next, when Vm (t) is demodulated, demodulation is alternately performed using different reference signals, and the polarity of the demodulation voltage is inverted when a negative bias is applied. (Or inversion at positive bias). As a result, in the demodulated signal Vd, the noise that varies with δφ and −δφ is canceled out, and only the magnetic flux signal that varies with δφ remains regardless of the bias direction. The magnetic flux that is proportional to this demodulated signal is SQUID
When SQUID is fed back to the loop, the SQUID is locked in a constant magnetic flux state, and the feedback current becomes an output proportional to the signal magnetic flux. In this output, noise other than the noise shown in FIG. 6 is eliminated from the above-mentioned three types of noise that cause fluctuations in the V (φ) characteristic, so SQ
The noise of the UID device can be reduced.
前記第２図のタイムチャートに戻って考案すると、雑音
による磁束変動はバイアス電流の向きにより変化するの
でφm の点線で示す状態となる。そして変調電圧Ｖｆm
の雑音成分はＩb の正，負によらず同位相であるので参
照信号の正負により符号が変化し、復調信号Ｖd の点線
のようになる。よって雑音による出力は積分器または低
域フィルタによって除去できることになるわけである。Returning to the time chart of FIG. 2, when devised, the fluctuation of the magnetic flux due to noise changes depending on the direction of the bias current, so that the state shown by the dotted line of φm is obtained. And the modulation voltage Vfm
Since the noise component of is in the same phase regardless of whether Ib is positive or negative, the sign changes depending on whether the reference signal is positive or negative, and becomes like the dotted line of the demodulated signal Vd. Therefore, the output due to noise can be removed by the integrator or the low-pass filter.
ところで、直流ＳＱＵＩＤ装置の雑音−周波数特性では
白色雑音が 100〜1000Ｈｚ以上で見られ、それより低い
周波数では周波数の減少とともに増加する雑音が存在す
る。この低周波数雑音は特に低周波数(100Ｈｚ以下)の
信号を測定する場合には重大な問題となる。低周波数雑
音の原因は明確ではないが、何らかの要因でＳＱＵＩＤ
のパラメータ（例えば抵抗や臨界電流値）が変動するこ
とが考えられる。このような変動によりＶ（φ）特性は
等価的な電圧変動δＶと磁束変動δφの両者により変動
する。ここで、磁束変動はバイアス電流の向きにより反
転するような性質をもっている。従って本発明のＳＱＵ
ＩＤ装置によれば低周波雑音を低減することで可能とな
る。By the way, in the noise-frequency characteristics of the DC SQUID device, white noise is seen at 100 to 1000 Hz or higher, and at frequencies lower than that, noise that increases with decreasing frequency exists. This low frequency noise becomes a serious problem especially when measuring low frequency signals (100 Hz or less). The cause of low frequency noise is not clear, but due to some factors, SQUID
It is conceivable that the parameters (for example, resistance and critical current value) vary. Due to such variation, the V (φ) characteristic varies due to both the equivalent voltage variation δV and the magnetic flux variation δφ. Here, the magnetic flux fluctuation has the property of being inverted depending on the direction of the bias current. Therefore, the SQU of the present invention
According to the ID device, it is possible to reduce low frequency noise.
本発明は前記実施例に限定されず種々の変形実施が可能
である。The present invention is not limited to the above embodiment, and various modifications can be made.
前記実施例ではバイアス電流Ｉb を直線的な立上り及び
立下りを有する矩形波としたが、これを第８図に示すよ
うに立上り立下りが傾斜面となるような矩形波としても
よい。通常ＳＱＵＩＤの電圧Ｖは正バイアスと負バイア
スで直流成分を持つためバイアス電流Ｉb の変化時に変
調電圧Ｖm(t)には第９図のようなスパイク電圧が生ずる
ことになる。これを第８図の如き立上り、立下りを有す
る矩形波とすることにより上記スパイク分を減少させる
ことができるという利点がある。また、変調磁束の周波
数よりもバイアス電流の周波数のほうが低いので、単位
時間に生じる上記スパイク分の数が少ないという利点も
ある。Although the bias current Ib is a rectangular wave having a linear rising and falling in the above-mentioned embodiment, it may be a rectangular wave having a rising and falling slope as shown in FIG. Normally, the SQUID voltage V has a DC component with a positive bias and a negative bias, so that a spike voltage as shown in FIG. 9 is generated in the modulation voltage Vm (t) when the bias current Ib changes. There is an advantage that the spike amount can be reduced by making this into a rectangular wave having a rising edge and a falling edge as shown in FIG. Further, since the frequency of the bias current is lower than the frequency of the modulation magnetic flux, there is an advantage that the number of spikes generated in a unit time is small.
［発明の効果］ 以上詳述した本発明によれば、ＳＱＵＩＤを構成するジ
ョセフソン素子に含まれる抵抗が発生する熱雑音のみで
なく、端子電圧Ｖの変動による雑音や低周波雑音をも除
去でき、大幅な雑音低域化が図れるＳＱＵＩＤ装置を提
供することができる。[Effects of the Invention] According to the present invention described in detail above, not only the thermal noise generated by the resistance included in the Josephson element constituting the SQUID but also the noise due to the fluctuation of the terminal voltage V and the low frequency noise can be removed. Therefore, it is possible to provide an SQUID device capable of significantly reducing the noise band.
第１図は本発明ＳＱＵＩＤ装置の一実施例を示す回路ブ
ロック図、第２図及び第３図は上記実施例の動作説明の
ためのタイムチャート、第４図乃至第７図は種々の雑音
源の説明図、第８図は本発明の他の実施例に用いられる
バイアス電流波形図、第９図はその実施例による効果説
明図、第10図はＳＱＵＩＤの原理図、第１１図は公知例
に基づく動作を説明するためのタイムチャート、第12図
は公知例の問題点を説明するためのタイムチャートであ
る。 １……発振器、２……バイアス電流発生回路、 ３……変調磁束発生回路、４……交流増幅回路、 ５，６……位相変調回路、７……参照信号切換手段、 ９……積分器。FIG. 1 is a circuit block diagram showing one embodiment of the SQUID device of the present invention, FIGS. 2 and 3 are time charts for explaining the operation of the above embodiment, and FIGS. 4 to 7 are various noise sources. FIG. 8, FIG. 8 is a bias current waveform diagram used in another embodiment of the present invention, FIG. 9 is an explanatory view of effects by the embodiment, FIG. 10 is a principle diagram of SQUID, and FIG. 11 is a known example. FIG. 12 is a time chart for explaining the operation based on FIG. 12, and FIG. 12 is a time chart for explaining the problems of the known example. 1 ... Oscillator, 2 ... Bias current generating circuit, 3 ... Modulating magnetic flux generating circuit, 4 ... AC amplifying circuit, 5,6 ... Phase modulating circuit, 7 ... Reference signal switching means, 9 ... Integrator .
Claims (3)
手段とからなる直流型ＳＱＵＩＤ装置において、前記直
流型ＳＱＵＩＤに周波数ｆb を有する正，負の交番バイ
アスを与えるバイアス電流供給手段と、このバイアス電
流の周波数ｆb より高い周波数であって、この周波数ｆ
b の整数倍の周波数ｆm の交流磁束を与えることにより
前記直流型ＳＱＵＩＤの電圧を変調する変調磁束供給手
段と、前記変調電圧を復調し、この復調電圧について前
記正，負バイアス時のそれぞれの電圧を参照信号として
連続波形を作成する復調手段と、この復調信号を磁束と
して前記直流型ＳＱＵＩＤにフィードバックする手段と
を備えたことを特徴とする直流型ＳＱＵＩＤ装置。1. A direct current type SQUID device comprising a direct current type SQUID and means for driving and controlling the same, and bias current supply means for applying a positive and negative alternating bias having a frequency fb to the direct current type SQUID, and this bias. A frequency higher than the frequency fb of the current, and this frequency f
Modulating magnetic flux supplying means for modulating the voltage of the DC type SQUID by giving an alternating magnetic flux of frequency fm which is an integral multiple of b, and demodulating the modulating voltage, and for the demodulated voltage, the positive and negative bias voltages respectively. A DC type SQUID device comprising: demodulation means for creating a continuous waveform using the reference signal as a reference signal and means for feeding back the demodulated signal as magnetic flux to the DC type SQUID.
の周波数ｆb の４倍としたことを特徴とする特許請求の
範囲第１項記載の直流型ＳＱＵＩＤ装置。2. The DC SQUID device according to claim 1, wherein the frequency fm of the alternating magnetic flux is four times the frequency fb of the bias current.
がり時に傾斜を持つ交番波形であることを特徴とする特
許請求の範囲第１項記載の直流型ＳＱＵＩＤ装置。3. The DC SQUID device according to claim 1, wherein the bias current has an alternating waveform having a slope at rising and falling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62246860A JPH0638103B2 (en) | 1987-09-30 | 1987-09-30 | DC type SQUID device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62246860A JPH0638103B2 (en) | 1987-09-30 | 1987-09-30 | DC type SQUID device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6488382A JPS6488382A (en) | 1989-04-03 |
| JPH0638103B2 true JPH0638103B2 (en) | 1994-05-18 |
Family
ID=17154803
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62246860A Expired - Lifetime JPH0638103B2 (en) | 1987-09-30 | 1987-09-30 | DC type SQUID device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0638103B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0573987B1 (en) * | 1992-06-10 | 2000-05-24 | Canon Kabushiki Kaisha | Recording material confining means for a recording apparatus |
-
1987
- 1987-09-30 JP JP62246860A patent/JPH0638103B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6488382A (en) | 1989-04-03 |
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