Memory effect in balanced Josephson comparators

Ortlepp, T.; Volkmann, Mark H.; Yamanashi, Yuki

doi:10.1016/j.physc.2014.02.003

Cited by 13 publications

(10 citation statements)

References 16 publications

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“…Experimental results in comparison with simulation results. Simulation and experiment 1 belong to the FLUXONICS Foundry process [7] and experiment 2 belong to the AIST standard process [12]. required to adjust the bias current to obtain the minimum gray zone for a certain clock frequency.…”

Section: Resultsmentioning

confidence: 99%

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Experimental Analysis of the Bias Dependent Sensitivity of a Josephson Comparator

Haddad

Engert

Brandel

et al. 2015

IEEE Trans. Appl. Supercond.

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The Josephson comparator is one of the building blocks of superconductor electronics. It is used as a decision element in all analog and digital circuits. For fast high-bandwidth analog-to-digital converters as well as for digital circuits with reduced switching energy its high sensitivity is most important. Thermal noise limits its decision uncertainty. In this work we analyze the influence of the bias current on the gray zone of a Josephson comparator. Circuit simulations are compared against experimental data. The experimental analysis shows a characteristic dependence of the gray zone on the bias current. We can identify a clear minimum value. This point is related to a certain clock frequency. At low frequencies the simulated relationship between the gray zone and the bias current is in very good agreement with experimental results. The comparison confirmed the circuit model and enables to adjust the design to certain applications to realize the best trade-off between clock frequency and grey zone. The article describes the experimental validation procedure and a derived normalized dependency in detail.

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Section: Resultsmentioning

confidence: 99%

“…Since we intend to derive a more general rule, the most interesting question is the influence of the critical current density on this data. We include the recent experimental data [12] about a Josephson comparator fabricated using the 2.5 kA/cm 2 standard process of AIST Japan [13]. Fig.…”

Section: Resultsmentioning

confidence: 99%

Experimental Analysis of the Bias Dependent Sensitivity of a Josephson Comparator

Haddad

Engert

Brandel

et al. 2015

IEEE Trans. Appl. Supercond.

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“…The circuit simulation results indicate the narrow gray zone width of the QFP can be obtained by using small  L and long t rise . Therefore, trade-off between current sensitivity and decision time of the QFP is confirmed like the Josephson current comparator based on the SFQ circuit[22].…”

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confidence: 88%

“…As shown in figure 3, the gray zone of the QFP reduces with increase in rise time of the excitation current I x . This is because the long decision process reduces the effective bandwidth of thermal noises and therefore reduces its influence[22].Assuming Gauss distribution of thermal current in the resisters, the output probability of the QFP can be fitted using the error function as…”

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confidence: 99%

Evaluation of current sensitivity of quantum flux parametron

Yamanashi

Matsushima

Takeuchi

et al. 2017

Supercond. Sci. Technol.

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Current sensitivity of quantum flux parametron (QFP) was evaluated by measuring gray zone width on the basis of both circuit simulation and measurements for superconducting sensing systems composed of a superconducting sensor array and superconducting read-out and signal processing circuits. Simulation results indicate the narrow gray zone width can be obtained by decreasing inductances comprising the QFP. Moreover, both high-sensitivity and low-power operation of the QFP can be utilized by using optimized circuit parameters and the excitation 2 current that has long rise time. Gray zone width of approximately 0.5 A, which is smaller than that of the Josephson current comparator based on a single flux quantum circuit, was experimentally obtained by using the trapezoidal excitation current that has rise time of 50 s. These results indicate the QFP is promising for the read-out circuit in the superconducting sensing systems because of high-sensitivity and low-power operation.

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“…Because the superconducting circuits comprising superconducting quantum interference (SQUID) loops have a high sensitivity to a magnetic flux or currents, the operation speed and stability are limited by the noises in the circuit. The influence of the thermal noise at 4.2 K on the SFQ and QFP circuit operations has been numerically and experimentally studied [11][12][13][14][15][16]. The influence of 1/f noise, which is believed to be caused by the trapping of quasi-particles in the defects of the superconducting film [17], on the high-temperature superconductor Manuscript receipt and acceptance dates will be inserted here.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Effects of 1/fNoise on Superconducting Circuits

Tsuna

Yamanashi

Yoshikawa

2020

IEEE Trans. Appl. Supercond.

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We analyzed the influence of 1/f noise in superconducting circuits on circuit operation using an analog circuit simulation. We devised a circuit simulation considering the 1/f noise using a conventional analog circuit simulator that can analyze the influence of thermal noises. In the circuit simulation, we used a passive filter that has a transfer function of -3 dB/oct to convert the Gaussian distributed white noise into the 1/f noise. We analyzed the gray zone characteristics of both the QFP and a singleflux-quantum current comparator considering both thermal and 1/f noises; the calculated gray zone width characteristics agree well with experimental results. Moreover, the influence of the 1/f noise is dominant in low operating speed regions for the QFP. These results indicate that the influence of the 1/f noise should be carefully considered to design superconducting circuits driven by a low-frequency clock.

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Memory effect in balanced Josephson comparators

Cited by 13 publications

References 16 publications

Experimental Analysis of the Bias Dependent Sensitivity of a Josephson Comparator

Experimental Analysis of the Bias Dependent Sensitivity of a Josephson Comparator

Evaluation of current sensitivity of quantum flux parametron

Investigation of the Effects of 1/fNoise on Superconducting Circuits

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