SU737851A1

SU737851A1 - Ultra-low voltage measuring device

Info

Publication number: SU737851A1
Application number: SU772548894A
Authority: SU
Inventors: Геннадий Семенович Кривой
Original assignee: Омский политехнический институт
Priority date: 1977-12-01
Filing date: 1977-12-01
Publication date: 1980-05-30

Description

Изобретение относится к технике измерения ультранизких электрических напряжений ниже 10'⁹ В с использованием явления сверхпроводимости и эффекта Джозефсона в слабосвязанных сверхпроводниках. .The invention relates to techniques for measuring ultra-low electrical voltages below 10 ' ⁹ V using the phenomenon of superconductivity and the Josephson effect in loosely coupled superconductors. .

Известны автокомпенсационные вольтметры ультранизких напряжений, в которых в качестве нуль-органа используются сверхпроводящие квантовые интерференционные датчики-сквиды [1]. Эти вольтметры содержат сквид,электронную схему усиления,детектирования и фильтрации сигнала со сквида, выходной измерительный прибор, цепь компенсации и 'связанную со сквидом катушку индуктивности, к зажимам которой подключено измеряемое напряжение, Информация об измеряемом напряжении в таких вольтметрах представлена в аналоговой форме'.Self-compensating ultra-low voltage voltmeters are known, in which superconducting quantum interference squid sensors are used as a zero-organ [1]. These voltmeters contain a squid, an electronic circuit for amplifying, detecting and filtering a signal from a squid, an output measuring device, a compensation circuit, and an inductance coil connected to the squid, to the terminals of which a measured voltage is connected.The information on the measured voltage in such voltmeters is presented in analog form.

. Выявление полярности измеряемого напряжения в принятой системе отсчета производится по полярности выходного напряжения. Недостатком таких вольтметров является аналоговая форма сигнала и необходимость калибровки коэффициента преобразования.. Identification of the polarity of the measured voltage in the adopted reference system is made by the polarity of the output voltage. The disadvantage of such voltmeters is the analog waveform and the need to calibrate the conversion coefficient.

Известен также вольтметр ультранизких напряжений, рассматриваемый нами в качестве прототипа, содержа- щий частично резистивный сквид-ресквид, связанный индуктивно с колебательным контуром, подключенным к 5 усилителю высокой частоты, на выходе которого включен амплитудный детектор и частотомер [2]. На ресквид подается магнитный поток ВЧ-накачки, Например, от отдельного генератора, 10 подключённого к катушке, индуктивно связанной с ресквидом. Измеряемое напряжение прикладывается к резистивному участку ресквида.An ultra-low voltage voltmeter is also known, which we consider as a prototype, which contains a partially resistive SQUID-RESQUID, connected inductively with an oscillatory circuit connected to a 5 high-frequency amplifier, the output of which includes an amplitude detector and a frequency meter [2]. A magnetic flux of RF pumping is applied to the resquid, for example, from a separate generator 10 connected to a coil inductively coupled to the resquid. The measured voltage is applied to the resistive portion of the resquid.

Генератор, усилитель и детектор 15 образуют блок высокочастотной накачки, усиления· и амплитудного детектирования,· который может быть реализован и другими средствами, например, без генератора, когда для ВЧ-накачки используется автогенерация усилителя. Этот .вольтметр является цифровым, причем измеряемое напряжение преобразуется в частоту в'ресквйдёв соответствии с соотношением Джозефсона:The generator, amplifier and detector 15 form a block of high-frequency pumping, amplification · and amplitude detection, · which can be implemented by other means, for example, without a generator, when the autogeneration of the amplifier is used for RF pumping. This .voltmeter is digital, and the measured voltage is converted to a frequency equal to the corresponding Josephson ratio:

·₽,«и /ф х х о где f_x - частота джозефсоновской осцилляции;· ₽, “and / f x x o where f _x is the frequency of the Josephson oscillation;

U_x - напряжение на переходе Джо·: зефсона, .......U _x - voltage at the Joe · junction: Zephson, .......

Ф_оаИка =:2,07-10^F _about aIka =: 2.07-10 ^

Вб - квант магнитого потока.Wb is the magnetic flux quantum.

Джозёфсоновская осцилляция вызывает периодическое с частотой f_xизменение импеданса ресквида, Что приводит к амплитудной модуляции напряжения на колебательном контуре. После усиления этого напряжения усилителем высокой частоты и детектирования амплитудным детектором на его выхбде появляется переменное напряжение с частотой f_x . Частота f_x измеряется частотомером. Коэффициент преобразования' А измеряемого н^пряжедия'в частоту заранее известен и определяется только мировыми постоянными:The Josephson oscillation causes a periodic change in the impedance of the resqueed at a frequency f _x , which leads to amplitude modulation of the voltage across the oscillating circuit. After amplifying this voltage with a high-frequency amplifier and detecting it with an amplitude detector, an alternating voltage with a frequency f _x appears on its output. The frequency f _x is measured by a frequency meter. The conversion coefficient 'A of the measured n ^ yayediya' to the frequency is known in advance and is determined only by world constants:

но Ъоbut b

Поэтому калибровка вольтметра не требуется, если используется электронно-счетный частотомер.Therefore, calibration of the voltmeter is not required if an electronically counted frequency meter is used.

При подаче на вход известного вольтметра напряжений различной ^:полярности в принятой системе отсчета значение частоты f/ зависит только от модуля измеряемого' напряжения и 'не зависит от его полярности . Это' явля· ёТЙя' нёдо'статком известного вольтметра и'не позволяет выявлять полярность измеряемого напряжения, что ограничивает область применения известного вольтметра.When applying to the input of a known voltmeter voltages of different polarity ^: in the adopted reference frame, the frequency value f / depends only on the module of the measured voltage and does not depend on its polarity. This is a "fotos" of the known voltmeter and does not allow to detect the polarity of the measured voltage, which limits the scope of the known voltmeter.

Цель изобре'тения - определение полярности измеряемого напряжения.The purpose of the invention is to determine the polarity of the measured voltage.

Для достижения поставленной цели в устройство для измерения ультранизн ких напряжений, содержащий частично резистивный сквид, индуктивно связанный с колебательным контуром, .подключенным к блоку высокочастотной накачки, состоящему из последовательно соединенных усилителя с автогенерацией и детектора, на выходе которого включен частотомер, входные зажимы, подключенные к резистивной части сквида, и резистор, введены генератор двухполярных симметричных прямоугольных импульсов (меандра) и интегратор. Вход интегратора подключен к генератору импульсов, а выход через резистор — к катушке индуктивности колебательного контура. Чс} ст от омер выполнен на⁴ рёвер си в ных сметчиках, вход направления счета которых соединен с генератором импульсов.To achieve this goal, an ultralow voltage measuring device containing a partially resistive squid inductively coupled to an oscillating circuit connected to a high-frequency pumping unit consisting of a self-oscillating amplifier and a detector connected in series with a frequency meter at its output, input terminals connected to the resistive part of the squid, and the resistor, a bipolar symmetric rectangular pulse generator (meander) and an integrator are introduced. The integrator input is connected to the pulse generator, and the output through the resistor is connected to the inductance coil of the oscillatory circuit. Hours} cm from the meters were made on ⁴ rotary counters, the input of the direction of counting of which is connected to the pulse generator.

На фиг. 1 изображена структурная схема устройства; на фиг. 2 - временные диаграммы его работы. / Устройство для измерения ультранизких напряжений содержат ресквдд 1 с переходом Джозефсона 2 и зажимами 3, на которые подается измеряемое напряжение. Ресквйд 1 индуктивно связан с катушкой индуктивности 4 колебательного контура 5, подключенного к входу усилителя 6 высокой частоты,. работающего в автогёнерационном режиме, в связи с чем отпадает необходимость в отдельном генераторе высокочастотной накачки’. На выходе усилителя 6 включен амплитудный детекторIn FIG. 1 shows a block diagram of a device; in FIG. 2 - time diagrams of his work. / The device for measuring ultra-low voltages contains reskvdd 1 with the transition of Josephson 2 and clamps 3, to which the measured voltage is applied. Resquid 1 is inductively connected to the inductance coil 4 of the oscillating circuit 5 connected to the input of the high-frequency amplifier 6. working in auto-generating mode, and therefore there is no need for a separate high-frequency pump generator ’. The output of the amplifier 6 includes an amplitude detector

7. Усилитель би амплитудный детектор 7 составляют блок 8 высокочастотной накачки. С выхода блока 8 сигнал подается на частотомер 9, выполненный На реверсивных счетчиках. Генератор 10 меандра подключен, к входу интегратора 11, выход которого через развязывающий резистор 12 подключен к катушке индуктивности7. The amplifier bi-amplitude detector 7 comprise a high-frequency pumping unit 8. From the output of block 8, the signal is fed to a frequency meter 9, made on reversible counters. The meander generator 10 is connected to the input of the integrator 11, the output of which through the decoupling resistor 12 is connected to the inductor

4. Для управления напряжением счета реверсивных счетчиков частотомера используется меандр, поэтому генератор 10 подключен к входу 13 управ ления направлением счета.4. A meander is used to control the counting voltage of the reversible counters of the frequency meter; therefore, the generator 10 is connected to the counting direction control input 13.

с генератора 10 на вход интегратора 11 поступает напряжение меандра (кривая 14 на фиг.2). С выхода интегратора 10 результат интегрирования меандра — пилообразное напряжение задает в катушке индуктивности 4 пилообразный ток (кривая 15). Сопротивление резистора 12 достаточно велико, чтобы выход интегратора 11 не шунтировал контур 5 и не ухудшал его эд добротность.Пилообразный ток индуцирует в контуре ресквида 1 ЭДС (кривая 16), повторяющую по форме меандр. Амплитуда ЭДС равна Е. ЭДС суммируется с положительным в выбранной сисj. теме отсчета измеряемым напряжением + и_х (линия 17), а результат суммирования (кривая 18) приложен к переходу Джозефсона 2. В положи-вельйые полупери оды меандра амплитуда напряжения на переходе Джозефсона равна /ϋ_χ + Е/, а в отрицательные полупериоды равна /и* - Е/. В соответствии с соотношением Джозефсона в ресквиде 1 возникает осцилляция, частота которой (кривая 19) прямо 45 пропорциональна модулю напряжения (кривая 18). В положительные полупериоды меандра эта частота равна /f_£+ f_x/,' а в отрицательные полупериоды равна /fg ” /· После уси50 ления и детектирования на выходе блока 8 появляется сигнал, частота которого измеряется частотомером 9 отдельно в положительный и отрицательный полупериоды меандра 14. Меандр 14 управляет направлением ³³ Счета реверсивных счетчиков частотомера 9, причем в положительный по’лупёриод меандра о суще ст вл яет ся 'сложение, а в отрицательный полупериод.- вычитание. Разность, запи-; 60 санная в счетчиках после окончания одного периода меандра, положительна, так как /f_t + ί_χ /> /f_E- f_x/. Когда измеряемое напряжение U_x(линия 20) отрицательно, то к пере65 ,ходу Джозефсона 2 приложено напряжеJ37851from the generator 10 to the input of the integrator 11 receives the voltage of the meander (curve 14 in figure 2). From the output of the integrator 10, the result of integrating the meander - the sawtooth voltage sets the sawtooth current in the inductance coil 4 (curve 15). The resistance of the resistor 12 is large enough so that the output of the integrator 11 does not bypass the circuit 5 and does not impair its Q factor. A sawtooth current induces an EMF in the circuit of the rescid 1 (curve 16), repeating in the form of a meander. The amplitude of the EMF is equal to E. EMF is summed with positive in the selected system. the reference point is measured by the voltage + and _x (line 17), and the summation result (curve 18) is applied to the Josephson 2 transition. For positive half-lengths of the meander, the voltage amplitude at the Josephson transition is / ϋ _χ + E /, and in negative half-periods it is / and * - E /. In accordance with the Josephson relation in resquid 1, an oscillation occurs, the frequency of which (curve 19) is directly proportional to the voltage modulus (curve 18). In the positive half-periods of the meander, this frequency is / f _£ + f _x /, 'and in the negative half-periods it is / fg ”/ · After amplification and detection at the output of block 8, a signal appears whose frequency is measured by the frequency meter 9 separately in the positive and negative half-periods of the meander 14. The meander 14 controls the direction ^{33 of the} Account of the reverse counters of the frequency meter 9, moreover, the addition is positive in the positive half-period of the meander and the subtraction is in the negative half-period. The difference, write down; 60 sled in the counters after the end of one period of the meander is positive, since / f _t + _ί _χ /> / f _E - f _x /. When the measured voltage U _x (line 20) is negative, then voltage is applied to Josephson 2, stroke J37851

Лие (кривая 21), причем амплитуда этого напряжения в положительные по-? лупериода меандра равна /Е - и_х/, а в отрицательные⁴, полупериода равна /-Е-и_х/.Lie (curve 21), and the amplitude of this voltage in positive? the meander luperiod is equal to / E - and _x /, and in negative ⁴ , the half-period is equal to / E and _x /.

В этом случае возникает осцилляция с частотой,показанной на фиг.2 кривой 22, а число, записанное в реверсивных счетчиках частотомера 9 в положительный полупериод меандра, будет меньше, чем число импульсов, вычитаемое в отрицательный полупериод меандра. Следовательно, разность, записанная в счетчиках по истечении одного периода меандра, отрицательна.In this case, an oscillation occurs with the frequency shown in Fig. 2 of curve 22, and the number recorded in the reversible counters of the frequency meter 9 in the positive half-wave of the meander will be less than the number of pulses subtracted in the negative half-wave of the meander. Therefore, the difference recorded in the counters after one period of the meander is negative.

Полярность измеряемого напряжения может быть выявлена, например, во втором полупериоде меандра,когда в процессе вычитания разность, записанная в счетчиках, становится равной нулю (если напряжение ϋ_χ отрицательно) , или на протяжении всего второго полупериода меандра не принимает нулевого значения (когда напряжение U_x положительно).The polarity of the measured voltage can be detected, for example, in the second square wave of the meander, when in the process of subtraction the difference recorded in the counters becomes zero (if the voltage ϋ _{χ is} negative), or throughout the second half-wave of the square wave it does not take zero value (when the voltage U _x positive).

Claims

(54) DEVICE FOR MEASURING ULTRANIZEDS The invention relates to a technique for measuring ultralow electrical voltages below 10 V. using the phenomenon of superconductivity and the Josephson effect in weakly coupled superconductors. . Autocompensation ultra-low voltage voltmeters are known in which superconducting quantum sensors SQUIDs 1 are used as a null organ. These voltmeters contain a squid electronic circuit for amplifying, detecting and filtering a signal from a squid, an output measurement, a compensation circuit, and an associated squid inductance coil , to which the measured voltage is connected to the terminals. Information on the measured voltage in such voltmeters is presented in analog form. The polarity of the measured voltage in the received reference system is determined by the polarity of the output voltage. The disadvantage of such voltmeters is analogue waveforms and the need to calibrate the conversion factor. Also known is a ultra-low voltage voltmeter, considered as a prototype by us as a prototype, containing a partially resistive SQUID-rectified, connected inductively with an oscillatory circuit connected to a high-frequency amplifier, the output of which includes amplitude detector i-bfi and frequency meter 2. Recursive RF flux is applied to the flux. For example, from a separate generator connected to a coil that is inductively coupled to a rescue. A measured voltage is applied to the resistive section of the resquad. The generator, amplifier, and detector form a high-frequency pumping unit, amplification, and amplitude detection (which can also be implemented by other means, for example, without a generator, when the autogeneration of the amplifier is used for RF pumping). This -voltmeter is digital, and the measure- ment of our marriage is converted to the frequency of the fault according to the Josephson ratio: -; . where f is the frequency of the Josephson oscillation; One voltage at the Josephson junction, ahka 2.07-10 Wb is a magnetic flux quantum, Josephson oscillation wBBieT periodic with frequency fy and resistance impedance leads to amplitude modulation of the voltage on the oscillating circuit. An amplitude of high frequency and detection by an amplitude detector at its height appears alternating voltage. with frequency f; . The frequency f is measured by a frequency meter. Coefficient of conversion: vani} 1 А 1йс1 ф ё1 «Ш i npfl :) KeTHi« rff the frequency is known in advance and. is determined only by the world constants: df ze -. Therefore, calibration of a voltmeter is not required if an electron counting frequency meter is used. When applied to the input of a known voltmeter, voltages of different polarity in the received reference system. The value of the frequency f depends only on the modulus of the measured voltage 1 and depends on its polarity. This is clearly indicated by the voltage source of the voltmeter. polarity of the measured voltage, which limits the scope of application of a known voltmeter. The purpose of the invention is to determine the polarity of the measured voltage. To achieve this goal, a device for measuring ultra-high voltages, including a partly resistive squid, is inductively Evan with an oscillatory circuit, connected to an i-switch and high: otoch: pumping, consisting of Postgenerally connected amplifier with autogeneration and detector, at the output which included the frequency counter input terminals. Connected to the resistive part of the SQUID, and resistor, a generator of two-polar symmetric rectangular pulses (meander) and an integrator are introduced. The integrator input is connected to a pulse generator, and the output via a resistor is connected to an oscillating circuit inductance circuit, Fr c is the result of the input voltage on jieBfep power meters, and the count direction input is connected to a pulse generator. FIG. 1 shows a block diagram of the device; in fig. 2 - time diagrams of his work,; A device for measuring ultra low voltages contains a reskvdd I with a Josephson junction 2 and clamps 3, to which a measured voltage is applied, Reskvyd 1 inductively St. It is connected with the inductance coil 4 of the rail of the circuit 5 connected to the input of the high-frequency amplifier 6. working in Zhvtogyo 1ZionZionnm mode; therefore, there is no need for a separate high-frequency pump generator. At the output of amplifier 6, an amplitude detector 7 is turned on, Amplifier 6 and an amplitude detector 7 comprise a high-frequency pumping unit 8, From the output of unit 8 it is fed to a frequency meter 9, performed on reversible counters. Generator 10 meander is connected. To the input of the integrator 11, the output of which is connected to the inductor 4 through the decoupling resistor 12, a square wave is used to control the counting voltage of the reversible counters of the frequency meter 9, therefore the generator 10 is connected to the input 13 of the control of the counting direction. live meander (curve 14 in FIG. 2). From the output of the integrator 10, the result of the integration of the meander - sawtooth voltage sets 4 sawtooth current (curve 15) in the inductance coil. Resistance of resistor 12 is large enough so that the output of integrator 11 does not shunt circuit 5 and does not degrade its Q-factor. The sawtooth current induces in the resqued circuit 1 EMF ( curve 16), repeating in shape a square wave. The amplitude of the EMF is equal to E, the EMF is summed with the measured voltage in the chosen reference system, h - Ujj; (line 17), and the result of the summation (curve 18) is applied to the Josephson 2 transition, B is positive and the amplitude of the Josephson junction is equal to / Uv + Е /, and in negative half-periods it is equal to / U - E /, in accordance with the Josephson ratio in rescande 1, 5 oscillations occur, whose frequency (curve 19) is directly proportional to the voltage module (curve 18), in the positive half-periods of the meander, this frequency is equal to / fg + fj /, and in negative half-periods it is / fp - j /. After amplification and detection at the output of block 8 and 6, the signal whose frequency is measured by frequency meter 9 separately into the positive and negative half-periods of the meander 14, the quadrant 14 directs the counting direction of the reversible counters frequently. Tomera 5, and in the positive half-frame of the meander, there is an addition, and a negative half-period is n. - subtraction. Difference, record; in the counters after the end of one Period of the meander, is positive, because / fj + f // - t x / When the measured voltage and (line 20) is negative, then the voltage is applied to curve (Jose 21), and the amplitude of this voltage in the positive on the looper meanders is equal to / E -, and in negative, the half periods is equal to / -E-UX /. . In this case, an oscillation occurs with the frequency shown in Fig. 2 by curve 22, and the number recorded in the reversible counters of the frequency meter 9 in the positive meander half-period will be less than the number of pulses subtracted in the negative half-period of the meander. Therefore, the spacing recorded in the counters after one period of the meander is negative. The polarity of the measured voltage can be detected, for example, in the second half-period of the meander, when in the process of subtracting the difference recorded in the counters becomes zero (if the voltage U negative), or over the entire second half period of the meander does not take a zero value (when the voltage Uj is positive). The invention The device for measuring ultra-low voltages, containing part of an inverse squid, is inductively coupled to an oscillating circuit connected to a high-frequency pumping unit consisting of series-connected amplifiers with auto-, oscillator, and a detector at the output of which a frequency meter is turned on. OzKymy, connected to the resistive part of the SQUID, and the resistor, are about the same, in order that, for the purpose of your polarity of the measured, voltage, the generator of two polar rectangular symmetric and pulses and an integrator, whose input is connected to a gyro or a puller, and the output via a resistor to an oscillating circuit induction coil, and the frequency meter is made on reversible meters, the count control input of which is connected to the generator mpu l with c. -. Sources of information taken into account during the examination I.- Solimar L. The tunnel effect in superconductors and its application. M., Mir, 1974, p. 388.

2. US Patent 3,622,881,. cl. 324-120, 11/23/71.