JPH06224638A - Josephson oscillator - Google Patents
Josephson oscillatorInfo
- Publication number
- JPH06224638A JPH06224638A JP5011688A JP1168893A JPH06224638A JP H06224638 A JPH06224638 A JP H06224638A JP 5011688 A JP5011688 A JP 5011688A JP 1168893 A JP1168893 A JP 1168893A JP H06224638 A JPH06224638 A JP H06224638A
- Authority
- JP
- Japan
- Prior art keywords
- josephson
- oscillator
- ring resonator
- josephson junctions
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000010409 thin film Substances 0.000 claims abstract description 6
- 230000010355 oscillation Effects 0.000 description 10
- 230000005668 Josephson effect Effects 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 239000002887 superconductor Substances 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 230000005428 wave function Effects 0.000 description 1
Landscapes
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はマイクロ波ないしサブミ
リ波帯の発振に利用する。特にジョセフソン接合を用い
た発振器における出力インピーダンス整合に関する。BACKGROUND OF THE INVENTION The present invention is used for oscillating in the microwave or submillimeter wave band. In particular, it relates to output impedance matching in an oscillator using Josephson junctions.
【０００２】[0002]
【従来の技術】ジョセフソン接合に電圧Ｖが加わると、
超伝導電子の波動関数（オーダーパラメータθ）の位相
差が時間的に変動する。これはジョセフソン効果の式に
より次のように記述される。2. Description of the Related Art When a voltage V is applied to a Josephson junction,
The phase difference of the wave function (order parameter θ) of superconducting electrons fluctuates with time. This is described by the Josephson effect formula as follows.
【０００３】[0003]
【数１】 超伝導電流Ｉは、ジョセフソン臨界電流Ｉc により、 Ｉ＝Ｉc sin θ と表されるから、[Equation 1] The superconducting current I is expressed as I = I c sin θ by the Josephson critical current I c ,
【０００４】[0004]
【数２】 なる交流電流が発生する。[Equation 2] AC current is generated.
【０００５】[0005]
【発明が解決しようとする課題】しかし、ジョセフソン
接合のインピーダンスは高々０．１Ω程度と極めて低
く、通常のマイクロ波回路で用いられる特性インピーダ
ンス５０Ωの回路系とは整合性が悪く、その発振出力を
効率的に取り出すことが困難であった。However, the impedance of the Josephson junction is as low as about 0.1 Ω at most, which is inconsistent with a circuit system having a characteristic impedance of 50 Ω used in a usual microwave circuit, and its oscillation output is low. It was difficult to take out efficiently.
【０００６】本発明は、このような課題を解決し、外部
回路との整合性が高いジョセフソン発振器を提供するこ
とを目的とする。An object of the present invention is to solve the above problems and to provide a Josephson oscillator having high compatibility with an external circuit.
【０００７】[0007]
【課題を解決するための手段】本発明のジョセフソン発
振器は、偶数個のジョセフソン接合と、この偶数個のジ
ョセフソン接合を実質的に等間隔の直列に接続してリン
グ共振器を構成する超伝導薄膜からなるストリップ線路
と、このリング共振器に沿って隣接するジョセフソン接
合どうしに互いに逆向きの実質的に等しい直流電圧が印
加されるようにストリップ線路に接続されたバイアス回
路とを備えたことを特徴とする。According to the Josephson oscillator of the present invention, an even number of Josephson junctions and the even number of Josephson junctions are connected in series at substantially equal intervals to form a ring resonator. A strip line made of a superconducting thin film and a bias circuit connected to the strip line so that substantially equal DC voltages in opposite directions are applied to adjacent Josephson junctions along the ring resonator. It is characterized by that.
【０００８】[0008]
【作用】ジョセフソン接合を直列に接続してリング共振
器を形成する。この共振器の共振周波数と等しい交流電
流が得られるように各ジョセフソン接合に電圧を印加す
ると、リング共振器上で定在波が発生する。したがっ
て、リング共振器の特性インピーダンス、すなわちリン
グ共振器を構成するストリップ線路の特性インピーダン
スを外部のマイクロ波回路のインピーダンスと同程度に
すれば、発振出力を効率よく取り出すことができる。[Operation] Josephson junctions are connected in series to form a ring resonator. When a voltage is applied to each Josephson junction so that an alternating current equal to the resonance frequency of this resonator can be obtained, a standing wave is generated on the ring resonator. Therefore, if the characteristic impedance of the ring resonator, that is, the characteristic impedance of the strip line forming the ring resonator is set to the same level as the impedance of the external microwave circuit, the oscillation output can be efficiently extracted.
【０００９】[0009]
【実施例】図１は本発明実施例のジョセフソン発振器を
示す平面図であり、図２はそのＡ−Ａ断面図である。1 is a plan view showing a Josephson oscillator according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line A--A.
【００１０】このジョセフソン発振器は、ジョセフソン
接合１、２と、このジョセフソン接合１、２に直流電圧
を印加するバイアス回路としてバイアス線４、５とを備
える。ここで本実施例の特徴とするところは、ジョセフ
ソン接合が２個設けられ、この２個のジョセフソン接合
１、２を実質的に等間隔の直列に接続してリング共振器
を構成する超伝導薄膜からなるストリップ線路３を備
え、バイアス線４、５はリング共振器に沿って隣接する
ジョセフソン接合１、２どうしに互いに逆向きの実質的
に等しい直流電圧が印加されるようにストリップ線路３
に接続されたことにある。The Josephson oscillator includes Josephson junctions 1 and 2 and bias lines 4 and 5 as a bias circuit for applying a DC voltage to the Josephson junctions 1 and 2. Here, the feature of this embodiment is that two Josephson junctions are provided, and these two Josephson junctions 1 and 2 are connected in series at substantially equal intervals to form a ring resonator. A strip line 3 made of a conductive thin film is provided, and the bias lines 4 and 5 are strip lines so that the Josephson junctions 1 and 2 adjacent to each other along the ring resonator are applied with substantially equal DC voltages in opposite directions. Three
Has been connected to.
【００１１】このジョセフソン発振器を製造するには、
低誘電損材料の基板７の上に薄膜のグランドプレーン８
を形成し、その上に特性インピーダンスで決定される厚
みを有する誘電体層９を形成し、さらにその上に超伝導
体からなるストリップ線路３をリング状に形成する。こ
のとき、ストリップ線路３にジョセフソン接合１、２を
形成する。さらに、これらのジョセフソン接合１、２に
バイアスを印加するためのバイアス線４、５と、発振出
力を外部に取り出すためのストリップ線路によるカプラ
６とを設ける。To manufacture this Josephson oscillator,
A thin film ground plane 8 on a substrate 7 of low dielectric loss material
Is formed, a dielectric layer 9 having a thickness determined by the characteristic impedance is formed thereon, and a strip line 3 made of a superconductor is formed thereon in a ring shape. At this time, Josephson junctions 1 and 2 are formed on the strip line 3. Further, there are provided bias lines 4 and 5 for applying a bias to these Josephson junctions 1 and 2, and a strip line coupler 6 for extracting the oscillation output to the outside.
【００１２】ジョセフソン接合１、２としては、二つの
超伝導体がわずかに接触した弱結合型、あるいは二つの
超伝導体の間に薄い（〜５０Å）絶縁層を設けたトンネ
ル型その他の構造を用いることができる。基板７として
は、例えばサファイアを用いる。グランドプレーン８は
ストリップ線路に対して接地電位となる面であり、超伝
導薄膜を用いることが望ましい。誘電体層９としては、
例えばＳｉＯ2 を用いる。The Josephson junctions 1 and 2 have a weak coupling type in which two superconductors are slightly in contact with each other, or a tunnel type structure in which a thin (˜50Å) insulating layer is provided between the two superconductors. Can be used. As the substrate 7, for example, sapphire is used. The ground plane 8 is a surface having a ground potential with respect to the strip line, and it is desirable to use a superconducting thin film. As the dielectric layer 9,
For example, SiO 2 is used.
【００１３】通常のマイクロ波回路で用いられる特性イ
ンピーダンスは５０Ωであり、ストリップ線路３からな
るリング共振器の特性インピーダンスも約５０Ωである
ことが望ましい。このためには、上述したように、誘電
体層９の誘電率および厚みを選択すればよい。It is desirable that the characteristic impedance used in a usual microwave circuit is 50Ω, and the characteristic impedance of the ring resonator formed of the strip line 3 is also about 50Ω. For this purpose, the dielectric constant and the thickness of the dielectric layer 9 may be selected as described above.
【００１４】リング共振器の共振周波数ｆ0 は、共振器
長すなわち円周をＬ、誘電体層９の比誘電率をεr とし
て、次の式で表される。ただし、ｃは光速である。The resonance frequency f 0 of the ring resonator is expressed by the following equation, where L is the resonator length or circumference and ε r is the relative permittivity of the dielectric layer 9. However, c is the speed of light.
【００１５】[0015]
【数３】 したがって、バイアス線４、５間には、共振周波数ｆ0
と等しい交流電流がジョセフソン接合１、２に流れるよ
うな電圧Ｖ0 を印加すればよい。このような電圧Ｖ
0 は、数２および数３にそれぞれ示した式から次のよう
に求められる。[Equation 3] Therefore, the resonance frequency f 0 is between the bias lines 4 and 5.
It suffices to apply a voltage V 0 such that an alternating current equal to the current flows in the Josephson junctions 1 and 2. Such voltage V
0 is calculated as follows from the equations shown in Equations 2 and 3, respectively.
【００１６】[0016]
【数４】 二つのジョセフソン接合１、２に同一バイアス電圧Ｖ0
が加えられるので、発振周波数もｆ0 で同一であり、し
かも２個の発振源が直列になっていることから、発振出
力も２倍になる。この発振出力は、カプラ６を通じて外
部に取り出すことができる。[Equation 4] The same bias voltage V 0 is applied to the two Josephson junctions 1 and 2.
Therefore, the oscillation frequency is the same at f 0 , and since the two oscillation sources are connected in series, the oscillation output is doubled. This oscillation output can be taken out through the coupler 6.
【００１７】具体的な数値例として、共振周波数ｆ0 ＝
１０ＧＨｚの発振器を得ようとする場合について説明す
る。このとき、誘電体層９としてＳｉＯ2 （εr ＝３）
を用いるとして、これらの値を数３の式に代入すると、 Ｌ＝１．７〔ｃｍ〕 が得られる。したがって、リング共振器の半径ｒは、 ｒ＝Ｌ／２π＝２．８〔ｍｍ〕 とすればよい。ジョセフソン接合に印加するバイアス電
圧は、数４の式から、 Ｖ0 ＝２１〔μＶ〕 となる。As a concrete numerical example, the resonance frequency f 0 =
A case of trying to obtain a 10 GHz oscillator will be described. At this time, SiO 2 (ε r = 3) is used as the dielectric layer 9.
Substituting these values into the equation of Formula 3 by using L, L = 1.7 [cm] is obtained. Therefore, the radius r of the ring resonator may be r = L / 2π = 2.8 [mm]. The bias voltage applied to the Josephson junction is V 0 = 21 [μV] from the equation (4).
【００１８】以上の実施例では交流ジョセフソン効果を
利用した発振器について説明したが、接合面積の大きい
ジョセフソン接合を用い、接合内の磁束の動きを利用す
るフラックス・フロー型の発振器の場合にも本発明を同
様に実施できる。また、上述した実施例のように交流ジ
ョセフソン効果を利用する場合でも、偶数個のジョセフ
ソン接合における発振が同期しないような場合には、非
対照な磁界を印加して同期させることができる。Although the oscillators utilizing the AC Josephson effect have been described in the above embodiments, a Josephson junction having a large junction area is also used in a flux flow type oscillator utilizing the movement of the magnetic flux in the junction. The present invention can be similarly implemented. Further, even when the AC Josephson effect is used as in the above-mentioned embodiment, when the oscillations in the even number of Josephson junctions are not synchronized, it is possible to apply an asymmetric magnetic field for synchronization.
【００１９】[0019]
【発明の効果】以上説明したように、本発明のジョセフ
ソン発振器は、選択された特性インピーダンスをもつ共
振器内にジョセフソン接合を形成するので、外部回路と
の間でインピーダンスを整合させることができる。ま
た、共振器が高いＱ値を有する超伝導共振器であるた
め、発振周波数の線幅は極めて狭く、かつ多少のバイア
ス電圧の変動に対しても周波数のゆらぎを小さくするこ
とができる。さらに、出力がジョセフソン接合の数に比
例するので、発振出力を従来より大きくすることができ
る。As described above, since the Josephson oscillator of the present invention forms the Josephson junction in the resonator having the selected characteristic impedance, the impedance can be matched with the external circuit. it can. Further, since the resonator is a superconducting resonator having a high Q value, the line width of the oscillation frequency is extremely narrow, and the fluctuation of the frequency can be reduced even if the bias voltage changes to some extent. Further, since the output is proportional to the number of Josephson junctions, the oscillation output can be made larger than before.
【図１】本発明実施例のジョセフソン共振器を示す平面
図。FIG. 1 is a plan view showing a Josephson resonator according to an embodiment of the present invention.
【図２】Ａ−Ａ断面図。FIG. 2 is a sectional view taken along line AA.
１、２ ジョセフソン接合 ３ ストリップ線路 ４、５ バイアス線 ６ カプラ ７ 基板 ８ グランドプレーン ９ 誘電体層 1, 2 Josephson junction 3 Strip line 4, 5 Bias line 6 Coupler 7 Substrate 8 Ground plane 9 Dielectric layer
Claims (3)
路とを備えたジョセフソン発振器において、 上記ジョセフソン接合が偶数個設けられ、 この偶数個のジョセフソン接合を実質的に等間隔の直列
に接続してリング共振器を構成する超伝導薄膜からなる
ストリップ線路を備え、 上記バイアス回路は上記リング共振器に沿って隣接する
ジョセフソン接合どうしに互いに逆向きの実質的に等し
い直流電圧が印加されるように上記ストリップ線路に接
続されたことを特徴とするジョセフソン発振器。1. A Josephson oscillator comprising a Josephson junction and a bias circuit for applying a DC voltage to the Josephson junction, wherein an even number of Josephson junctions are provided, and the even number of Josephson junctions is substantially provided. A strip line composed of a superconducting thin film that is connected in series at regular intervals to form a ring resonator, and the bias circuit is configured such that the Josephson junctions adjacent to each other along the ring resonator are substantially opposite in direction. A Josephson oscillator connected to the strip line so that a DC voltage equal to is applied.
は約５０Ωである請求項１記載のジョセフソン発振器。2. The Josephson oscillator according to claim 1, wherein the characteristic impedance of the ring resonator is about 50Ω.
振器を動作させる方法において、 上記バイアス回路には、各ジョセフソン接合を流れる交
流電流の周波数が上記リング共振器の共振周波数に等し
くなる電圧を印加することを特徴とするジョセフソン発
振器の動作方法。3. The method for operating a Josephson oscillator according to claim 1, wherein the bias circuit is provided with a voltage at which a frequency of an alternating current flowing through each Josephson junction becomes equal to a resonance frequency of the ring resonator. A method of operating a Josephson oscillator characterized by applying a voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5011688A JPH06224638A (en) | 1993-01-27 | 1993-01-27 | Josephson oscillator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5011688A JPH06224638A (en) | 1993-01-27 | 1993-01-27 | Josephson oscillator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06224638A true JPH06224638A (en) | 1994-08-12 |
Family
ID=11784971
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5011688A Pending JPH06224638A (en) | 1993-01-27 | 1993-01-27 | Josephson oscillator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06224638A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0744827A1 (en) * | 1995-05-25 | 1996-11-27 | Matsushita Electric Industrial Co., Ltd | High frequency system including a superconductive device |
| KR20040006952A (en) * | 2002-07-16 | 2004-01-24 | 박익모 | Microstrip Ring with a Compact Tunable Microwave Bandgap Structure |
| US7253701B2 (en) * | 2004-11-30 | 2007-08-07 | Northrop Grumman Corporation | Multiplexed amplifier |
-
1993
- 1993-01-27 JP JP5011688A patent/JPH06224638A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0744827A1 (en) * | 1995-05-25 | 1996-11-27 | Matsushita Electric Industrial Co., Ltd | High frequency system including a superconductive device |
| US5757243A (en) * | 1995-05-25 | 1998-05-26 | Matsushita Electric Industrial Co., Ltd. | High frequency system including a superconductive device and temperature controlling apparatus |
| KR20040006952A (en) * | 2002-07-16 | 2004-01-24 | 박익모 | Microstrip Ring with a Compact Tunable Microwave Bandgap Structure |
| US7253701B2 (en) * | 2004-11-30 | 2007-08-07 | Northrop Grumman Corporation | Multiplexed amplifier |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |