Fast Multicore FastHenry and a Tetrahedral Modeling Method for Inductance Extraction of Complex 3D Geometries

Jackman, Kyle; Fourie, Coenrad J.

doi:10.1109/isec.2015.7383459

Cited by 17 publications

(10 citation statements)

References 17 publications

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“…The numerical solver FFH [11] calculates current density in every segment of a three-dimensional model when one port connected to some structures in the model is excited with 1 Volt at a specified frequency. The segments represent all conducting objects, and may be resistive or superconductive.…”

Section: Calculation Of Branch Impedances For a Networkmentioning

confidence: 99%

“…In earlier work we focused on modelling methods to ensure fast calculation time while retaining calculation accuracy [10], but vast improvements to the numerical engine FFH [11] now mostly makes the time constraint irrelevant. Today, model size is limited for practical purposes only by the available memory on a computer.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we use InductEx [9] and the solver FFH [11] for all inductance calculations. InductEx remains the only simulator other than Lmeter [5] that can handle full-gate superconductive circuit extractions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Inductance and Current Distribution Extraction in Nb Multilayer Circuits with Superconductive and Resistive Components

Fourie

Takeuchi

Yoshikawa

2016

IEICE Trans. Electron.

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SUMMARYWe describe a calculation tool and modeling methods to find self and mutual inductance and current distribution in superconductive multilayer circuit layouts. Accuracy of the numerical solver is discussed and compared with experimental measurements. Effects of modeling parameter selection on calculation results are shown, and we make conclusions on the selection of modeling parameters for fast but sufficiently accurate calculations when calibration methods are used. Circuit theory for the calculation of branch impedances from the output of the numerical solver is discussed, and compensation for solution difficulties is shown through example. We elaborate on the construction of extraction models for superconductive integrated circuits, with and without resistive branches. We also propose a method to calculate current distribution in a multilayer circuit with multiple bias current feed points. Finally, detailed examples are shown where the effects of stacked vias, bias pillars, coupling, ground connection stacks and ground return currents in circuit layouts for the AIST advanced process (ADP2) and standard process (STP2) are analyzed. We show that multilayer inductance and current distribution extraction in such circuits provides much more information than merely branch inductance, and can be used to improve layouts; for example through reduced coupling between conductors.

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Section: Calculation Of Branch Impedances For a Networkmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Inductance and Current Distribution Extraction in Nb Multilayer Circuits with Superconductive and Resistive Components

Fourie

Takeuchi

Yoshikawa

2016

IEICE Trans. Electron.

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“…A precise calculation of the current density in the loop is essential, as it forms the basis for the rest of the calculation of 2 . To perform the bulk of this computation, we employ the 64 bit superconducting version of FastHenry [27], which computes the current distribution as an intermediary step to its designed purpose of inductance extraction. To perform this computation, a preprocessor in FastHenry first approximates a given thin-film structure by discretizing it into a large, two-dimensional network of rectangular prisms (hereafter referred to simply as 'segments') of height equivalent to the film thickness, each carrying an unknown current along its length that is uniform across its width and thickness.…”

Section: Calculation Of Current Densitymentioning

confidence: 99%

Mean square flux noise in SQUIDs and qubits: numerical calculations

Anton¹,

Sognnaes²,

Birenbaum³

et al. 2013

Supercond. Sci. Technol.

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The performance of SQUIDs and superconducting qubits based on magnetic flux is degraded by the presence of magnetic flux noise with a spectral density scaling approximately inversely with frequency. It is generally accepted that the noise arises from the random reversal of spins on the surface of the superconductors. We introduce a numerical method of calculating the mean square flux noise 2 from independently fluctuating spins on the surface of thin-film loops of arbitrary geometry. By reciprocity, 2 is proportional to B(r) 2 , where B(r) is the magnetic field generated by a circulating current around the loop and r varies over the loop surface. By discretizing the loop nonuniformly, we efficiently and accurately compute the current distribution and resulting magnetic field, which may vary rapidly across the loop. We use this method to compute 2 in a number of scenarios in which we systematically vary physical parameters of the loop. We compare our simulations to an earlier analytic result predicting that 2 ∝ R/W in the limit where the loop radius R is much greater than the linewidth W. We further show that the previously neglected contribution of edge spins to 2 is significant-even dominant-in narrow-linewidth loops.

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“…Analytical and numerical methods have been developed for calculating the magnetic fields and current densities of superconducting strips [7][8][9][10][11] and circular discs [12][13][14][15]; however, these methods are limited to well-defined geometries. Numerous tools are available for solving current densities within superconducting circuits [16][17][18][19][20][21][22], but these tools lack the ability to calculate magnetic field distributions.…”

Section: Introductionmentioning

confidence: 99%

Multipole accelerated magnetic field calculations for superconducting circuits

Jackman

Fourie

2018

Supercond. Sci. Technol.

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This paper presents an adaptive fast multipole algorithm to accelerate the computation of magnetic fields surrounding current-carrying superconducting volumes. The algorithm is based on a hierarchical tree of cubic cells and vector spherical harmonics are used to approximate the gradient of Green's function. The derivation of the multipole and local expansion coefficients are presented, including the implementation of these coefficients within FastCap's multipole algorithm. We demonstrate how the proposed algorithm can be used to calculate the magnetic fields of trapped flux and the magnetic fields surrounding type-II superconducting microstrips and compare the results to analytical solutions. The overall complexity of our multipole algorithm is found empirically to rise linearly, N ( ), with N evaluation points.

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Fast Multicore FastHenry and a Tetrahedral Modeling Method for Inductance Extraction of Complex 3D Geometries

Cited by 17 publications

References 17 publications

Inductance and Current Distribution Extraction in Nb Multilayer Circuits with Superconductive and Resistive Components

Inductance and Current Distribution Extraction in Nb Multilayer Circuits with Superconductive and Resistive Components

Mean square flux noise in SQUIDs and qubits: numerical calculations

Multipole accelerated magnetic field calculations for superconducting circuits

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