KR20020078325A - low-noise wide-bandwidth current amplifier using SQUID - Google Patents

low-noise wide-bandwidth current amplifier using SQUID Download PDF

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KR20020078325A
KR20020078325A KR1020010018669A KR20010018669A KR20020078325A KR 20020078325 A KR20020078325 A KR 20020078325A KR 1020010018669 A KR1020010018669 A KR 1020010018669A KR 20010018669 A KR20010018669 A KR 20010018669A KR 20020078325 A KR20020078325 A KR 20020078325A
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South Korea
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squid
current
current amplifier
thin film
low noise
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KR1020010018669A
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Korean (ko)
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이용호
김진목
권혁찬
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한국표준과학연구원
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Publication of KR20020078325A publication Critical patent/KR20020078325A/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
    • H03K17/92—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of superconductive devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/372—Noise reduction and elimination in amplifier
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/825—Apparatus per se, device per se, or process of making or operating same
    • Y10S505/855—Amplifier
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/825—Apparatus per se, device per se, or process of making or operating same
    • Y10S505/856—Electrical transmission or interconnection system
    • Y10S505/857—Nonlinear solid-state device system or circuit
    • Y10S505/863—Stable state circuit for signal shaping, converting, or generating
    • Y10S505/864—Stable state circuit for signal shaping, converting, or generating with josephson junction

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  • Measuring Magnetic Variables (AREA)
  • Superconductor Devices And Manufacturing Methods Thereof (AREA)

Abstract

PURPOSE: A low noise broadband current amplifier by using a SQUID is provided to easily operate by simplifying a SQUID driving circuit and increasing a measurement bandwidth and a slewing velocity. CONSTITUTION: A low noise broadband current amplifier by using a SQUID includes a superconductive thin film(2) for increasing a resist value by rising a temperature thereof when an x-line pulse(5) is inputted to the superconductive thin film(2), an input coil(3), a bias resistor(4) connected to the superconductive thin film(2) for inputting for a direct current(6), a signal SQUID(14) for receiving a current pulse(7) through the input coil(3) and for applying a direct applying current(19), a reference junction(16), a direct current front amplifier(20), an integrator(21), a feedback resister(22) and a feedback coil(23). The low noise broadband current amplifier utilizes a double relaxation oscillation SQUID method and adopts a reference junction as well as a signal SQUID at the same time.

Description

스퀴드를 이용한 저잡음 광대역 전류증폭기{low-noise wide-bandwidth current amplifier using SQUID}Low-noise wide-bandwidth current amplifier using SQUID

본 발명은 저잡음 광대역 전류증폭기에 관한 것으로, 보다 상세하게는 이중이완발진 스퀴드(double relaxation oscillation SQUID)를 이용하며, 이중이완발진 스퀴드의 자속-전압 변환계수가 크므로 자속변조 및 임피던스 매칭회로가 필요없어 구동회로를 간단히 할 수 있음과 동시에 대역폭과 슬루잉 속도(slewing rate)를 높일 수 있는 저잡음 광대역 전류증폭기에 관한 것이다.The present invention relates to a low noise broadband current amplifier, and more particularly, using a double relaxation oscillation SQUID, and a magnetic flux-to-voltage conversion coefficient of the double relaxation oscillation squid is required, so that a flux modulation and an impedance matching circuit are required. The present invention relates to a low noise broadband current amplifier which can simplify the driving circuit and increase the bandwidth and slewing rate.

도 1은 한개의 직류스퀴드를 사용하여 전류펄스를 증폭하는 종래의 일실시예를 설명하기 위한 도면이다.1 is a view for explaining a conventional embodiment of amplifying a current pulse using a single DC squid.

도 1에서, 초전도박막(2)에 x-선(5)이 입사되면 초전도박막(2)의 저항증가에 따른 전류펄스(7)를 측정하므로써 x-선 에너지의 검출이 가능하다. 전류펄스(7)를 증폭하기 위해 도 1에 도시된 대로 한 개의 직류스퀴드(1)를 사용하여 증폭한다. 이러한 직류스퀴드(1)는 자속-전압 변환계수가 매우 작으므로, 직류스퀴드(1)신호를 측정하면 구동회로(10)에 의한 잡음이 우세하여 직류스퀴드(1)의 고감도 특성을 잃어버린다. 따라서, 이러한 직류스퀴드(1)의 감도를 유지하기 위해 임피던스 매칭회로인 저항(8)과 변압기(9)를 사용하며 스퀴드 구동은 위상민감검출방법을 사용해 왔다.In FIG. 1, when the x-ray 5 is incident on the superconducting thin film 2, the x-ray energy can be detected by measuring the current pulse 7 according to the increase in the resistance of the superconducting thin film 2. In order to amplify the current pulse (7) it is amplified using a single DC squid (1) as shown in FIG. Since the DC-squid 1 has a very small flux-to-voltage conversion coefficient, when the DC-squid 1 signal is measured, the noise caused by the driving circuit 10 prevails, and the high-sensitivity characteristic of the DC-squid 1 is lost. Therefore, the resistor 8 and the transformer 9 which are impedance matching circuits are used to maintain the sensitivity of the DC squid 1, and the squid driving has used a phase sensitive detection method.

도 2는 도 1에서 개시한 한 개의 직류스퀴드를 사용한 후, 직렬연결된 다수의 직류스퀴드를 사용하여 전류펄스를 증폭하는 종래의 다른 실시 예를 설명하기 위한 도면이다.FIG. 2 is a view for explaining another exemplary embodiment of amplifying a current pulse using a plurality of DC squids connected in series after using one DC squid disclosed in FIG. 1.

도 2에서 도 1과 동일참조번호를 갖는 구성은 동일한 기능을 한다. 도 2에서, 한개의 직류스퀴드(1)로 전류펄스(7)를 증폭한후 직렬로 연결된 다수개의 직류스퀴드들(12)로 다시 한번 증폭하는 과정을 거쳐 구동회로(13)에 연결한다. 이렇게 다수개의 직류스퀴드들(12)을 직렬연결하면 자속-전압 변환계수를 증가시킬 수 있으므로, 구동회로(13)에 의한 잡음을 줄이고 대역폭과 슬루잉 속도를 증가시킬 수 있다.In Fig. 2, the components having the same reference numerals as those in Fig. 1 function the same. In FIG. 2, the current pulse 7 is amplified by one DC squid 1 and then amplified by a plurality of DC squids 12 connected in series, and connected to the driving circuit 13. When the plurality of DC squids 12 are connected in series as described above, the magnetic flux-to-voltage conversion coefficient can be increased, thereby reducing noise by the driving circuit 13 and increasing bandwidth and slewing speed.

이러한 종래의 전류증폭기에 사용되는 하나의 직류스퀴드로 증폭하는 경우에 필요한 임피던스 매칭회로와 자속변조방식 및 위상민감검출방법은 스퀴드 구동회로를 복잡하게 하며, 자속-전압변환계수가 작아서 측정할 수 있는 대역폭과 슬루잉 속도를 충분히 높일 수 없었다. 따라서, 미세한 전류펄스의 증폭에 필요한 광대역 전류증폭기를 구성하기 곤란하였다. 이에 비해, 다수의 직류스퀴드를 직렬연결하여 증폭하는 경우에는 하나의 직류스퀴드로 증폭하는 경우보다 대역폭과 슬루잉 속도를 증가시킬 수 있다. 그러나, 다수의 직류스퀴드를 직렬 연결하므로 자속트랩이 발생할 가능성이 높고 동일한 특성을 갖는 직류스퀴드를 제작하기 어려운 문제가 있다. 또한, 변조코일과 스퀴드 사이의 상호 인덕턴스와 스퀴드의 동작조건이 모두 같아야 하며 다수의 직류스퀴드를 사용함에 따라 전력소모가 큰 문제점이 있었다.The impedance matching circuit, magnetic flux modulation method, and phase sensitive detection method required for amplifying a single DC squid used in the conventional current amplifier complicate the squid driving circuit, and the magnetic flux-voltage conversion coefficient can be measured. The bandwidth and slewing speed could not be increased sufficiently. Therefore, it is difficult to construct a wideband current amplifier for amplifying minute current pulses. In contrast, in the case of amplifying a plurality of DC squid in series, the bandwidth and the slewing speed may be increased than in the case of amplifying the single squid. However, since a plurality of DC squid is connected in series, there is a high possibility that a magnetic flux trap may occur and it is difficult to manufacture a DC squid having the same characteristics. In addition, the mutual inductance between the modulation coil and the squid and the operating conditions of the squid should all be the same, and there is a big problem in power consumption by using a plurality of DC squids.

따라서, 본 발명의 목적은 전술한 문제점을 해결할 수 있도록 구동회로를 간단히 하기 위해 자속-전압변환계수가 큰 이중이완발진 스퀴드를 사용하며, 구동회로를 간단히 할 수 있음과 동시에 대역폭과 슬루잉 속도(slewing rate)를 높일 수 있는 저잡음 광대역 전류증폭기를 제공함에 있다.Accordingly, an object of the present invention is to use a double relaxation oscillation squid having a large flux-to-voltage conversion coefficient to simplify the driving circuit so as to solve the above-mentioned problems, and to simplify the driving circuit and at the same time, the bandwidth and slewing speed It provides a low noise broadband current amplifier that can increase the slewing rate.

도 1은 한 개의 직류스퀴드를 사용하여 전류펄스를 증폭하는 종래의 일실시 예를 설명하기 위한 도면,1 is a view for explaining a conventional embodiment of amplifying a current pulse using a single DC squid,

도 2는 한 개의 직류스퀴드를 사용하여 전류펄스를 1차 증폭한 후, 직렬연결된 다수의 직류스퀴드를 사용하여 2차 증폭하는 종래의 다른 실시 예를 설명하기 위한 도면,2 is a view for explaining another conventional embodiment in which a first amplification of a current pulse using one DC squid, and then a second amplification using a plurality of DC squids connected in series;

도 3은 이중이완발진스퀴드의 등가회로도,3 is an equivalent circuit diagram of a double loose oscillating squid;

도 4는 본 발명의 일실시예에 따른 전류증폭기 구동회로의 개략도.4 is a schematic diagram of a current amplifier driving circuit according to an embodiment of the present invention;

* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings

1 : 직류스퀴드 2 : 초전도박막1: DC squid 2: Superconducting thin film

3 : 입력코일 4 : 바이어스 저항3: input coil 4: bias resistor

5 : x-선 6 : 직류전류5 x-ray 6 DC current

7 : 전류펄스 8 : 임피던스 매칭회로의 저항7 Current pulse 8 Resistance of impedance matching circuit

9 : 임피던스 매칭회로의 변압기 10 : 구동회로9: transformer of impedance matching circuit 10: driving circuit

11 : 변조코일 12 : 직렬연결된 다수의 직류스퀴드11: Modulation coil 12: Multiple DC squid connected in series

13 : 구동회로 14 : 신호스퀴드13 drive circuit 14 signal squid

15 : 조셉슨접합 16 : 기준접합15 Josephson junction 16 Reference junction

17 : 이완발진회로의 저항 18 : 이완발진회로의 인덕터17: resistance of the loose oscillation circuit 18: inductor of the loose oscillation circuit

19 : 직류바이어스전류 20 : 직류전단증폭기19 DC bias current 20 DC shear amplifier

21 : 적분기 22: 귀환저항21: integrator 22: feedback resistance

23 : 귀환코일23: return coil

이와 같은 목적을 달성하기 위한 본 발명에 따른 저잡음 광대역 전류증폭기는 이중이완발진 스퀴드 방식을 이용하고 신호스퀴드와 동시에 기준접합을 채택하는 것을 특징으로 한다.The low noise broadband current amplifier according to the present invention for achieving the above object is characterized by using a double relaxation oscillation Squid method and adopting a reference junction simultaneously with the signal squid.

이하, 첨부한 도면들을 참조하여 본 발명의 바람직한 실시예를 상세히 기술하기로 한다.Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

도 3은 이중이완발진스퀴드의 등가회로도이며, 도 4는 본 발명의 일실시예에 따른 전류증폭기 구동회로의 개략도이다.3 is an equivalent circuit diagram of a double relaxation oscillation squid, and FIG. 4 is a schematic diagram of a current amplifier driving circuit according to an embodiment of the present invention.

도 3에서 초전도박막(2)과 병렬로 바이어스저항(4)이 연결되어 있고, 초전도박막(2)은 전류펄스(7)를 발생시키며 이 전류펄스(7)는 입력코일(3)을 통해 신호스퀴드(14)에 자속신호로 전달된다. 신호스퀴드(14)는 기준접합(16)이 직렬로 연결되어 있고, 이와 병렬로 저항(17)과 인덕터(18)가 연결되며, 조셉슨접합(15)이 사용된다. 이때, 기준접합(16)의 면적을 신호스퀴드(14)에 사용된 조셉슨접합(15)의 전체면적의 70-80%범위로 하고 출력전압을 기준접합양단에서 측정하도록 한다.In FIG. 3, the bias resistor 4 is connected in parallel with the superconducting thin film 2, and the superconducting thin film 2 generates a current pulse 7 and the current pulse 7 signals through the input coil 3. It is transmitted to the squid 14 as a magnetic flux signal. In the signal squid 14, a reference junction 16 is connected in series, a resistor 17 and an inductor 18 are connected in parallel, and a Josephson junction 15 is used. At this time, the area of the reference junction 16 is 70-80% of the total area of the Josephson junction 15 used for the signal squid 14, and the output voltage is measured at both ends of the reference junction.

이러한 이중이완발진 스퀴드를 이용한 전류증폭기를 도 4의 구동회로도를 참조하여 설명한다.A current amplifier using such a double relaxation oscillation squid will be described with reference to the driving circuit diagram of FIG. 4.

도 4에서, x-선펄스(5)가 초전도박막(2)에 입사되면 초전도박막(2)의 온도가 상승하여 저항값이 증가한다. 초전도박막(2)과 병렬로 연결된 바이어스저항(4)에 직류전류(6)를 인가한다. 여기서, 바이어스저항(4)의 저항값을 초전도박막(2)의 저항값에 비해 충분히 작게하면(예를들면, 1/10이하)초전도박막(2)은 전압바이어스로 동작한다. 따라서, 초전도박막(2)의 온도 즉, 저항값을 일정하게 유지할 수 있다. x-선펄스(5)에 의해 초전도박막(2)의 저항변화가 10μs내외의 폭을 가진 전류펄스(7)를 발생시킨다. 이 전류펄스(7)는 입력코일(3)을 통해 신호스퀴드(14)에 자속신호로 전달되는데 전류펄스에 비례하는 스퀴드출력을 측정함으로써 x-선펄스(5)의 에너지를 알 수 있다. 이중이완발진 스퀴드는 직류인가전류(19)를 인가하며, 이때 기준접합(16) 양단에서 직류전단증폭기(20)를 사용하여 스퀴드 출력전압을 검출한다. 출력전압은 신호스퀴드(14)에 가해지는 자속신호에 따라 변하며 자속-전압 변환계수가 종래의 직류스퀴드에 비해 10배 이상 크다. 따라서, 실온의 직류전단증폭기(20)로 스퀴드 출력전압을 직접 검출할 수 있고, 자속변조나 위상민감검출회로 없이 적분기(21)와 귀환저항(22), 및 귀환코일(23)만으로 귀환회로를 구성할 수 있으므로 전류증폭기의 구성 및 동작이 간편하다. 측정할 수 있는 대역폭과 슬로잉 속도는 스퀴드의 자속-전압변환계수에 비례하므로 이중이완발진 스퀴드를 사용함으로써 종래의 직류스퀴드에 비해 대역폭과 슬루잉 속도를 높일 수 있다.In FIG. 4, when the x-ray pulse 5 is incident on the superconducting thin film 2, the temperature of the superconducting thin film 2 increases to increase the resistance value. The direct current (6) is applied to the bias resistor (4) connected in parallel with the superconducting thin film (2). Here, when the resistance value of the bias resistor 4 is sufficiently small compared to the resistance value of the superconducting thin film 2 (for example, 1/10 or less), the superconducting thin film 2 operates with a voltage bias. Therefore, the temperature of the superconducting thin film 2, that is, the resistance value can be kept constant. The resistance change of the superconducting thin film 2 by the x-ray pulses 5 generates a current pulse 7 having a width of about 10 mu s. The current pulse 7 is transmitted as a magnetic flux signal to the signal squid 14 through the input coil 3, and the energy of the x-ray pulse 5 can be known by measuring the squid output proportional to the current pulse. The double relaxed oscillating squid applies a DC applied current 19, and detects the squid output voltage using the DC shear amplifier 20 across the reference junction 16. The output voltage changes according to the magnetic flux signal applied to the signal squid 14 and the magnetic flux-to-voltage conversion coefficient is 10 times larger than that of the conventional DC squid. Therefore, the squid output voltage can be directly detected by the DC shear amplifier 20 at room temperature, and the feedback circuit is formed only by the integrator 21, the feedback resistor 22, and the feedback coil 23 without the flux modulation or the phase sensitive detection circuit. Since it can be configured, it is easy to configure and operate the current amplifier. The measurable bandwidth and slowing rate are proportional to the magnetic flux-to-voltage conversion coefficient of the squid. Thus, the use of the double-relaxed squid can increase the bandwidth and slewing speed compared to the conventional DC squid.

이러한 전류증폭기를 이용한 최적의 실험결과치를 보면, 신호스퀴드(14)의 인덕턴스를 110 pH, 기준접합(16)의 임계전류가 21 μA일 때 자속-전압 변환계수를 직류 스퀴드의 약 50배 수준인 2-5 mV/Φ0를 얻었다(Φ0는 자속양자). 직류인가전류(19)와 직류전단증폭기(20)를 사용한 간단한 구동회로를 사용하여, 입력코일(3)의 인덕턴스가 112 nH이고, 입력코일(3)과 신호스퀴드(14)와의 상호 인덕턴스가 3.2 nH일 때 100 Hz에서 2 pA/√Hz의 매우 우수한 전류잡음값을 얻었다.The optimal experimental result using the current amplifier shows that the magnetic flux-to-voltage conversion coefficient is about 50 times that of the DC squid when the inductance of the signal squid 14 is 110 pH and the threshold current of the reference junction 16 is 21 μA. 2-5 mV / Φ 0 was obtained (Φ 0 is the magnetic flux quantum). Using a simple driving circuit using a DC applied current 19 and a DC shear amplifier 20, the inductance of the input coil 3 is 112 nH, and the mutual inductance of the input coil 3 and the signal squid 14 is 3.2. At nH, a very good current noise of 2 pA / √Hz at 100 Hz was obtained.

본 발명은 스퀴드 구동회로를 간단히 하고 측정 대역폭 및 슬루잉 속도를 증가시켜 전류증폭기의 동작을 용이하게 하는 효과를 제공한다.The present invention provides the effect of simplifying the squid driving circuit and increasing the measurement bandwidth and slewing speed to facilitate the operation of the current amplifier.

Claims (2)

스퀴드를 이용한 저잡음 광대역 전류증폭기 구성에 있어서,In the low noise broadband current amplifier configuration using a squid, 이중이완발진 스퀴드 방식을 이용하고 신호스퀴드와 동시에 기준접합을 채택하는 것을 특징으로 하는 저잡음 광대역 전류증폭기.A low noise broadband current amplifier using a double relaxation oscillating squid method and adopting a reference junction simultaneously with a signal squid. 제 1항에 있어서, 상기 기준접합의 면적을 신호스퀴드에 사용된 조셉슨접합의 전체면적의 70-80%범위로 하고 출력전압을 기준접합 양단에서 측정하는 것을 특징으로 하는 저잡음 광대역 전류증폭기.2. The low noise broadband current amplifier of claim 1, wherein the area of the reference junction is in the range of 70-80% of the total area of the Josephson junction used in the signal squid and the output voltage is measured across the reference junction.
KR1020010018669A 2001-04-09 2001-04-09 low-noise wide-bandwidth current amplifier using SQUID KR20020078325A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7388371B2 (en) * 2006-04-14 2008-06-17 Korea Research Institute Of Standards And Science Method for controlling characteristics of double relaxation oscillation SQUID with reference junction
US7453263B2 (en) * 2006-05-09 2008-11-18 Korea Research Institute Of Standards And Science Reference current optimizing apparatus for controlling magnetic flux-voltage conversion characteristic of double relaxation oscillation squid

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7388371B2 (en) * 2006-04-14 2008-06-17 Korea Research Institute Of Standards And Science Method for controlling characteristics of double relaxation oscillation SQUID with reference junction
US7453263B2 (en) * 2006-05-09 2008-11-18 Korea Research Institute Of Standards And Science Reference current optimizing apparatus for controlling magnetic flux-voltage conversion characteristic of double relaxation oscillation squid

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