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@ -833,6 +833,22 @@
langid = {english}
}
@inproceedings{chituAlgorithmDesignConductive2020,
title = {Algorithm to {{Design Conductive Mesh}} for {{Tamperproof Envelope}}},
booktitle = {2020 {{IEEE}} 26th {{International Symposium}} for {{Design}} and {{Technology}} in {{Electronic Packaging}} ({{SIITME}})},
author = {Chiţu, Sorin and Vasile, Daniel Ciprian and Honceriu, Tudor Ioan and Svasta, Paul},
date = {2020-10},
pages = {106--108},
issn = {2642-7036},
doi = {10.1109/SIITME50350.2020.9292275},
url = {https://ieeexplore.ieee.org/document/9292275/?arnumber=9292275},
urldate = {2024-10-31},
abstract = {Protection of the Critical Security Parameters is a permanent concern for the designers, but also for the users of cryptographic equipment. The usage of a conductive mesh is a sensitive and efficient solution in order to protect the firmware, keys or any other sensitive data that could be contained in a cryptographic module. In order to improve the security provided by this principle, based on the flexibility of common technology that can be used to produce PCBs, an algorithm to produce particular designs of conductive mesh on PCBs starting from random bit strings is present in this article. Random design of conductive mesh is useful in order to increase the unpredictability of its electrical characteristics so, in addition to the sensitivity of this conductive mesh which will detect and react even to any attempt of measuring it by probes, an attacker will not have any information which can be exploited. The proposed innovative algorithm provides filling of the full area of envelope which cover the cryptographic module, even if its perimeter is irregular, according to necessary dimensions and profile, keeping traces on a dense grid, without any uncovered areas. The main advantage of the proposed solution consists of the possibility to implement a fully automated production flux, without human participation, and with an increased level of security due to unpredictable electrical characteristics of conductive mesh generated from a true random bit string.},
eventtitle = {2020 {{IEEE}} 26th {{International Symposium}} for {{Design}} and {{Technology}} in {{Electronic Packaging}} ({{SIITME}})},
keywords = {algorithm,Cryptography,Electric variables,Electronics packaging,Generators,mesh,Probes,Production,random,security,Sensitivity,tamperproof},
file = {/home/jaseg/Sync/Research/Zotero/Chiţu et al_2020_Algorithm to Design Conductive Mesh for Tamperproof Envelope.pdf;/home/jaseg/Zotero/storage/XPN3D8DA/9292275.html}
}
@article{choiHalbachMagneticCircuit2010,
title = {Halbach {{Magnetic Circuit}} for {{Voice Coil Motor}} in {{Hard Disk Drives}}},
author = {Choi, Young-Man and Ahn, Da-Hoon and Gweon, Dae-Gab and Jeong, Jae-Hwa},
@ -1041,6 +1057,24 @@
file = {/home/jaseg/Zotero/storage/PXJ2VHWV/Damgård and Scafuro - 2013 - Unconditionally Secure and Universally Composable .pdf}
}
@article{daneshDifferentiallyDrivenSymmetric2002,
title = {Differentially Driven Symmetric Microstrip Inductors},
author = {Danesh, M. and Long, J.R.},
date = {2002-01},
journaltitle = {IEEE Transactions on Microwave Theory and Techniques},
volume = {50},
number = {1},
pages = {332--341},
issn = {1557-9670},
doi = {10.1109/22.981285},
url = {https://ieeexplore.ieee.org/document/981285/?arnumber=981285},
urldate = {2024-10-31},
abstract = {A differentially excited symmetric inductor that enhances inductor quality (Q) factor on silicon RFICs is presented. Compared with an equivalent single-ended configuration, experimental data demonstrate that the differential inductor offers a 50\% greater Q factor and a broader range of operating frequencies. Predictions from full-wave simulations and a physics-based SPICE-compatible model are validated by experimental measurements on an inductor fabricated in a triple-level metal silicon technology. Application of the symmetric inductor to a cross-coupled oscillator improves output voltage swing and phase noise by 75\% and 1.8 dB, respectively (for a given power consumption), while chip area is reduced by 35\% compared to conventional inductor equivalents.},
eventtitle = {{{IEEE Transactions}} on {{Microwave Theory}} and {{Techniques}}},
keywords = {Frequency,Inductors,Microstrip,Phase noise,Predictive models,Q factor,Radiofrequency integrated circuits,Semiconductor device measurement,Silicon,Voltage-controlled oscillators},
file = {/home/jaseg/Sync/Research/Zotero/Danesh_Long_2002_Differentially driven symmetric microstrip inductors.pdf;/home/jaseg/Zotero/storage/M8393BNA/981285.html}
}
@article{darcoSecureComputationComputers2016,
title = {Secure Computation without Computers},
author = {D'Arco, Paolo and De Prisco, Roberto},
@ -1700,6 +1734,21 @@
file = {/home/jaseg/Zotero/storage/W896B45Z/Hanspach and Goetz - 2013 - On Covert Acoustical Mesh Networks in Air.pdf}
}
@inproceedings{haobijamQualityFactorEnhancement2007,
title = {Quality Factor Enhancement of {{CMOS}} Inductor with Pyramidal Winding of Metal Turns},
booktitle = {2007 {{International Workshop}} on {{Physics}} of {{Semiconductor Devices}}},
author = {Haobijam, Genemala and Paily, Roy},
date = {2007-12},
pages = {729--732},
doi = {10.1109/IWPSD.2007.4472624},
url = {https://ieeexplore.ieee.org/document/4472624/?arnumber=4472624&tag=1},
urldate = {2024-10-30},
abstract = {In order to exploit the available multilevel interconnects and to reduce the parasitic capacitances, the metal can be traced spirally up and/or down in a pyramidal manner. This paper presents two methods to improve the quality factor (Q) of pyramidically wound inductors. The first method utilizes bulk micromachining to improve the Q. Quality factor improvement of 14.7\% and 19.5\% and self resonating frequency improvement of 26.5\% and 30.6\% respectively were observed in 10 nH and 20 nH over conventional micromachined planar inductors. The second method to improve Q is by differential excitation and is illustrated for 8 nH and 23 nH symmetric pyramidal inductors. The performance of the pyramidically wound inductors are characterized using a full wave Electromagnetic simulator for a six metal layer 0.18 mum process.},
eventtitle = {2007 {{International Workshop}} on {{Physics}} of {{Semiconductor Devices}}},
keywords = {CMOS inductor,differential excitation,Etching,Inductors,Integrated inductor,micromachining,Micromachining,Parasitic capacitance,Q factor,Radiofrequency integrated circuits,Resonant frequency,Silicon,Spirals,Wounds},
file = {/home/jaseg/Sync/Research/Zotero/2007_Haobijam_Paily_Quality factor enhancement of CMOS inductor with pyramidal winding of metal.pdf;/home/jaseg/Zotero/storage/92HTG5MX/4472624.html}
}
@inproceedings{hastingsSoKGeneralPurpose2019,
title = {{{SoK}}: {{General Purpose Compilers}} for {{Secure Multi-Party Computation}}},
shorttitle = {{{SoK}}},
@ -1789,6 +1838,24 @@
file = {/home/jaseg/Sync/Research/Zotero/Hong et al_2020_Design and Compensation Control of a Flexible Instrument for Endoscopic Surgery.pdf;/home/jaseg/Zotero/storage/8CGJKAZ8/9196955.html}
}
@article{hsuAnalyticalDesignAlgorithm2008,
title = {Analytical {{Design Algorithm}} of {{Planar Inductor Layout}} in {{CMOS Technology}}},
author = {Hsu, Heng-Ming and Chan, Kai-Yuen and Chien, Hung-Chi and Kuan, Han-Chien},
date = {2008-11},
journaltitle = {IEEE Transactions on Electron Devices},
volume = {55},
number = {11},
pages = {3208--3213},
issn = {1557-9646},
doi = {10.1109/TED.2008.2004248},
url = {https://ieeexplore.ieee.org/document/4668566/?arnumber=4668566},
urldate = {2024-11-08},
abstract = {A layout design algorithm for a variable-width inductor is proposed to minimize metal resistance. For a given chip area, the proposed algorithm can rapidly design metal widths of each coil in a planar inductor due to the analytical form. Two on-chip inductors with identical chip areas and inductance are fabricated to verify the proposed method in foundry 90-nm CMOS technology. Measurement results demonstrate that the improvement of metal resistance in the proposed device is approximately 19\%. The results of this paper provide an effective algorithm to design a high-Q inductor for RFIC applications.},
eventtitle = {{{IEEE Transactions}} on {{Electron Devices}}},
keywords = {Analytical algorithm,CMOS integrated circuits,CMOS technology,Inductors,Layout,minimum resistance,on-chip inductor,Radiofrequency integrated circuits,Resistance,variable width},
file = {/home/jaseg/Sync/Research/Zotero/2008_Hsu et al_Analytical Design Algorithm of Planar Inductor Layout in CMOS Technology.pdf;/home/jaseg/Zotero/storage/CKPP397K/4668566.html}
}
@online{HttpsArxivOrg,
title = {{{https://arxiv.org/pdf/1909.13770}}},
url = {https://arxiv.org/pdf/1909.13770},
@ -2422,20 +2489,22 @@
file = {/home/jaseg/Zotero/storage/SPNJ8KBL/Launchbury et al. - 2014 - Application-Scale Secure Multiparty Computation.pdf}
}
@article{leePrintedSpiralWinding2011,
@article{leePrintedSpiralWinding2011a,
title = {Printed {{Spiral Winding Inductor With Wide Frequency Bandwidth}}},
author = {Lee, Chi Kwan and Su, Y. P. and Ron Hui, S. Y.},
date = {2011-10},
journaltitle = {IEEE Transactions on Power Electronics},
shortjournal = {IEEE Trans. Power Electron.},
volume = {26},
number = {10},
pages = {2936--2945},
issn = {0885-8993, 1941-0107},
issn = {1941-0107},
doi = {10.1109/TPEL.2010.2076318},
url = {http://ieeexplore.ieee.org/document/5580123/},
urldate = {2024-09-10},
file = {/home/jaseg/Sync/Research/Zotero/2011_Lee et al_Printed Spiral Winding Inductor With Wide Frequency Bandwidth.pdf}
url = {https://ieeexplore.ieee.org/document/5580123/?arnumber=5580123},
urldate = {2024-10-30},
abstract = {Winding parasitic capacitance is a major factor limiting the bandwidth of an inductor. In this paper, 1) the traditional, 2) the alternating, and 3) the partial alternating winding methods are evaluated for the multilayer printed spiral winding inductors for megahertz operations. The self-capacitances of various winding structures are estimated by the summation of parasitic capacitance among the turns of a winding. The electric field energy distributions in the inductors are derived from the voltage profiles to illustrate the relative magnitudes of winding parasitic capacitances. The results show that parasitic capacitance reduction can be achieved by reducing stored electric field energy. The partial alternating winding method is found to have the widest frequency bandwidth with reduced number of through-hole vias for multilayer printed spiral winding design. The theoretical analysis has been confirmed with practical measurements. The results provide useful information for the optimal design of coreless or core-based high-frequency planar magnetics.},
eventtitle = {{{IEEE Transactions}} on {{Power Electronics}}},
keywords = {Bandwidth,Electric fields,Inductors,Parasitic capacitance,Planar magnetic device,printed circuit board inductors,spiral winding,Spirals,Windings},
file = {/home/jaseg/Sync/Research/Zotero/2011_Lee et al_Printed Spiral Winding Inductor With Wide Frequency Bandwidth2.pdf;/home/jaseg/Zotero/storage/CXZSAL3U/5580123.html}
}
@article{leeSimpleWirelessPower2017,
@ -2554,6 +2623,24 @@
file = {/home/jaseg/Sync/Research/Zotero/Liu et al_2023_Improved Quantum Circuits for AES.pdf}
}
@article{liWirelessPowerTransfer2015,
title = {Wireless {{Power Transfer}} for {{Electric Vehicle Applications}}},
author = {Li, Siqi and Mi, Chunting Chris},
date = {2015-03},
journaltitle = {IEEE Journal of Emerging and Selected Topics in Power Electronics},
volume = {3},
number = {1},
pages = {4--17},
issn = {2168-6785},
doi = {10.1109/JESTPE.2014.2319453},
url = {https://ieeexplore.ieee.org/document/6804648/?arnumber=6804648},
urldate = {2024-11-08},
abstract = {Wireless power transfer (WPT) using magnetic resonance is the technology which could set human free from the annoying wires. In fact, the WPT adopts the same basic theory which has already been developed for at least 30 years with the term inductive power transfer. WPT technology is developing rapidly in recent years. At kilowatts power level, the transfer distance increases from several millimeters to several hundred millimeters with a grid to load efficiency above 90\%. The advances make the WPT very attractive to the electric vehicle (EV) charging applications in both stationary and dynamic charging scenarios. This paper reviewed the technologies in the WPT area applicable to EV wireless charging. By introducing WPT in EVs, the obstacles of charging time, range, and cost can be easily mitigated. Battery technology is no longer relevant in the mass market penetration of EVs. It is hoped that researchers could be encouraged by the state-of-the-art achievements, and push forward the further development of WPT as well as the expansion of EV.},
eventtitle = {{{IEEE Journal}} of {{Emerging}} and {{Selected Topics}} in {{Power Electronics}}},
keywords = {Batteries,Coils,Couplers,Couplings,Dynamic charging,electric vehicle (EV),Ferrites,inductive power transfer (IPT),Power electronics,safety guidelines,stationary charging,Wireless communication,wireless power transfer (WPT)},
file = {/home/jaseg/Sync/Research/Zotero/2015_Li_Mi_Wireless Power Transfer for Electric Vehicle Applications.pdf;/home/jaseg/Zotero/storage/QYEZNYUG/6804648.html}
}
@article{loMeasurementDeviceIndependentQuantumKey2012,
title = {Measurement-{{Device-Independent Quantum Key Distribution}}},
author = {Lo, Hoi-Kwong and Curty, Marcos and Qi, Bing},
@ -2625,6 +2712,24 @@
file = {/home/jaseg/Sync/Research/Zotero/Lope et al_2014_Frequency-Dependent Resistance of Planar Coils in Printed Circuit Board With.pdf;/home/jaseg/Zotero/storage/JJQHT5A5/6851880.html}
}
@article{lopez-villegasImprovementQualityFactor2000,
title = {Improvement of the Quality Factor of {{RF}} Integrated Inductors by Layout Optimization},
author = {Lopez-Villegas, J.M. and Samitier, J. and Cane, C. and Losantos, P. and Bausells, J.},
date = {2000-01},
journaltitle = {IEEE Transactions on Microwave Theory and Techniques},
volume = {48},
number = {1},
pages = {76--83},
issn = {1557-9670},
doi = {10.1109/22.817474},
url = {https://ieeexplore.ieee.org/document/817474/?arnumber=817474},
urldate = {2024-11-08},
abstract = {A systematic method to improve the quality (Q) factor of RF integrated inductors is presented in this paper. The proposed method is based on the layout optimization to minimize the series resistance of the inductor coil, taking into account both ohmic losses, due to conduction currents, and magnetically induced losses, due to eddy currents. The technique is particularly useful when applied to inductors in which the fabrication process includes integration substrate removal. However, it is also applicable to inductors on low-loss substrates. The method optimizes the width of the metal strip for each turn of the inductor coil, leading to a variable strip-width layout. The optimization procedure has been successfully applied to the design of square spiral inductors in a silicon-based multichip-module technology, complemented with silicon micromachining postprocessing. The obtained experimental results corroborate the validity of the proposed method. A Q factor of about 17 have been obtained for a 35-nH inductor at 1.5 GHz, with Q values higher than 40 predicted for a 20-nH inductor working at 3.5 GHz. The latter is up to a 60\% better than the best results for a single strip-width inductor working at the same frequency.},
eventtitle = {{{IEEE Transactions}} on {{Microwave Theory}} and {{Techniques}}},
keywords = {Coils,Design optimization,Eddy currents,Fabrication,Inductors,Magnetic losses,Optimization methods,Q factor,Radio frequency,Strips},
file = {/home/jaseg/Sync/Research/Zotero/2000_Lopez-Villegas et al_Improvement of the quality factor of RF integrated inductors by layout.pdf;/home/jaseg/Zotero/storage/GQKEU7DE/817474.html}
}
@article{loSecureQuantumKey2014,
title = {Secure Quantum Key Distribution},
author = {Lo, Hoi-Kwong and Curty, Marcos and Tamaki, Kiyoshi},
@ -2710,6 +2815,21 @@
file = {/home/jaseg/Zotero/storage/FCPRRWEK/Marhoefer et al. - Applicability of Quantum Cryptography for Securing.pdf}
}
@inproceedings{martinMultiturnTwistedInductor2016,
title = {A Multi-Turn Twisted Inductor for on-Chip Cross-Talk Reduction},
booktitle = {2016 {{IEEE International Conference}} on the {{Science}} of {{Electrical Engineering}} ({{ICSEE}})},
author = {Martin, Peter and Horn, Richard and Ben Atar, Kobi},
date = {2016-11},
pages = {1--5},
doi = {10.1109/ICSEE.2016.7806138},
url = {https://ieeexplore.ieee.org/document/7806138/?arnumber=7806138},
urldate = {2024-11-08},
abstract = {A Fully symmetric multi-turn twisted inductor is presented for the suppression of on-chip interference in the transmit chain of a LTE transceiver chip implemented in TSMC 65nm CMOS process. The inductor is ultra-compact, symmetrical and presents up to ×3 inductance density as compared to a standard spiral inductor. Magnetic coupling reduction of more than 12dB was measured and EM simulation results validate the design procedure. A simple and accurate closed form expression for the inductance estimation is introduced for the first time in the context of planar twisted-inductors to simplify the design process.},
eventtitle = {2016 {{IEEE International Conference}} on the {{Science}} of {{Electrical Engineering}} ({{ICSEE}})},
keywords = {closed-form inductance expression,Couplings,crosstalk,Figure-8 inductor,Frequency conversion,Inductance,Inductors,Injection-Lock Divider,Q-factor,Resonant frequency,Standards,Twisted-Inductor},
file = {/home/jaseg/Sync/Research/Zotero/2016_Martin et al_A multi-turn twisted inductor for on-chip cross-talk reduction.pdf;/home/jaseg/Zotero/storage/HIHNNITA/7806138.html}
}
@inproceedings{martinSealClubComputeraidedPaper2023,
title = {{{SealClub}}: {{Computer-aided Paper Document Authentication}}},
shorttitle = {{{SealClub}}},
@ -2878,6 +2998,25 @@
file = {/home/jaseg/Sync/Research/Zotero/2023_Monfared et al_LeakyOhm.pdf}
}
@article{mooreApplicationsWirelessPower2019,
title = {Applications of {{Wireless Power Transfer}} in {{Medicine}}: {{State-of-the-Art Reviews}}},
shorttitle = {Applications of {{Wireless Power Transfer}} in {{Medicine}}},
author = {Moore, Julian and Castellanos, Sharon and Xu, Sheng and Wood, Bradford and Ren, Hongliang and Tse, Zion Tsz Ho},
date = {2019-01},
journaltitle = {Annals of Biomedical Engineering},
shortjournal = {Ann Biomed Eng},
volume = {47},
number = {1},
pages = {22--38},
issn = {0090-6964, 1573-9686},
doi = {10.1007/s10439-018-02142-8},
url = {http://link.springer.com/10.1007/s10439-018-02142-8},
urldate = {2024-11-08},
abstract = {Magnetic resonance within the field of wireless power transfer has seen an increase in popularity over the past decades. This rise can be attributed to the technological advances of electronics and the increased efficiency of popular battery technologies. The same principles of electromagnetic theory can be applied to the medical field. Several medical devices intended for use inside the body use batteries and electrical circuits that could be powered wirelessly. Other medical devices limit the mobility or make patients uncomfortable while in use. The fundamental theory of electromagnetics can improve the field by solving some of these problems. This survey paper summarizes the recent uses and discoveries of wireless power in the medical field. A comprehensive search for papers was conducted using engineering search engines and included papers from related conferences. During the initial search, 247 papers were found then nonrelevant papers were eliminated to leave only suitable material. Seventeen relevant journal papers and/or conference papers were found, then separated into defined categories: Implants, Pumps, Ultrasound Imaging, and Gastrointestinal (GI) Endoscopy. The approach and methods for each paper were analyzed and compared yielding a comprehensive review of these state of the art technologies.},
langid = {english},
file = {/home/jaseg/Zotero/storage/JVKURIVI/Moore et al. - 2019 - Applications of Wireless Power Transfer in Medicin.pdf}
}
@article{morimotoSimultaneousMeasurementSpecific2006,
title = {Simultaneous Measurement of Specific Heat, Thermal Conductivity, and Thermal Diffusivity of Modified Barium Titanate Ceramics},
author = {Morimoto, Kohsuke and Sawai, Shinya and Hisano, Kumao and Yamamoto, Takashi},
@ -2931,6 +3070,41 @@
file = {/home/jaseg/Sync/Research/Zotero/2023_Mosavirik et al_Silicon Echoes2.pdf}
}
@article{mouEnergyEfficientAdaptiveDesign2017,
title = {Energy-{{Efficient}} and {{Adaptive Design}} for {{Wireless Power Transfer}} in {{Electric Vehicles}}},
author = {Mou, Xiaolin and Groling, Oliver and Sun, Hongjian},
date = {2017-09},
journaltitle = {IEEE Transactions on Industrial Electronics},
volume = {64},
number = {9},
pages = {7250--7260},
issn = {1557-9948},
doi = {10.1109/TIE.2017.2686299},
url = {https://ieeexplore.ieee.org/document/7885065/?arnumber=7885065},
urldate = {2024-11-08},
abstract = {Wireless power transfer (WPT) could revolutionize global transportation and accelerate growth in the electric vehicle (EV) market, offering an attractive alternative to cabled charging. Coil misalignment is inevitable due to driver parking behavior and has a detrimental effect on power transfer efficiency (PTE). This paper proposes a novel coil design and adaptive hardware to improve PTE in magnetic resonant coupling WPT and mitigate coil misalignment, a crucial roadblock in the acceptance of WPT for EVs. The new design was verified using ADS, providing a good match to theoretical analysis. Custom designed receiver and transmitter circuitry was used to simulate vehicle and parking bay conditions and obtain PTE data in a small-scale setup. Experimental results showed that PTE can be improved by 30\% at the array's center, and an impressive 90\% when misaligned by three-fourths of the array's radius. The proposed novel coil array achieves overall higher PTE compared to the benchmark single coil design.},
eventtitle = {{{IEEE Transactions}} on {{Industrial Electronics}}},
keywords = {Adaptive hardware,coil design,Couplings,electric vehicle (EV),Hardware,Inductive charging,Magnetic resonance,magnetic resonant coupling (MRC),misalignment,power transfer efficiency (PTE),Receivers,Transmitters,Windings,wireless power transfer (WPT)},
file = {/home/jaseg/Sync/Research/Zotero/2017_Mou et al_Energy-Efficient and Adaptive Design for Wireless Power Transfer in Electric.pdf;/home/jaseg/Zotero/storage/9EFPC8GL/7885065.html}
}
@inproceedings{mouWirelessPowerTransfer2015,
title = {Wireless {{Power Transfer}}: {{Survey}} and {{Roadmap}}},
shorttitle = {Wireless {{Power Transfer}}},
booktitle = {2015 {{IEEE}} 81st {{Vehicular Technology Conference}} ({{VTC Spring}})},
author = {Mou, Xiaolin and Sun, Hongjian},
date = {2015-05},
pages = {1--5},
issn = {1550-2252},
doi = {10.1109/VTCSpring.2015.7146165},
url = {https://ieeexplore.ieee.org/document/7146165/?arnumber=7146165},
urldate = {2024-11-07},
abstract = {Wireless power transfer (WPT) technologies have been widely used in many areas, e.g., the charging of electric toothbrush, mobile phones, and electric vehicles. This paper introduces fundamental principles of three WPT technologies, i.e., inductive coupling-based WPT, magnetic resonant coupling-based WPT, and electromagnetic radiation-based WPT, together with discussions of their strengths and weaknesses. Main research themes are then presented, i.e., improving the transmission efficiency and distance, and designing multiple transmitters/receivers. The state-of-the-art techniques are reviewed and categorised. Several WPT applications are described. Open research challenges are then presented with a brief discussion of potential roadmap.},
eventtitle = {2015 {{IEEE}} 81st {{Vehicular Technology Conference}} ({{VTC Spring}})},
keywords = {Couplings,Magnetic resonance,Receivers,Transmitters,Wireless communication,Wireless sensor networks},
file = {/home/jaseg/Sync/Research/Zotero/Mou_Sun_2015_Wireless Power Transfer.pdf;/home/jaseg/Zotero/storage/U6XA93RL/7146165.html}
}
@inproceedings{muehlmannMutualCouplingModeling2012,
title = {Mutual Coupling Modeling of {{NFC}} Antennas by Using Open-Source {{CAD}}/{{FEM}} Tools},
booktitle = {2012 {{IEEE International Conference}} on {{RFID-Technologies}} and {{Applications}} ({{RFID-TA}})},
@ -3107,6 +3281,24 @@
langid = {english}
}
@article{nguyenReviewComparisonSolid2020,
title = {A {{Review}} and {{Comparison}} of {{Solid}}, {{Multi-Strands}} and {{Litz Style PCB Winding}}},
author = {Nguyen, Minh Huy and Fortin Blanchette, Handy},
date = {2020-08-16},
journaltitle = {Electronics},
shortjournal = {Electronics},
volume = {9},
number = {8},
pages = {1324},
issn = {2079-9292},
doi = {10.3390/electronics9081324},
url = {https://www.mdpi.com/2079-9292/9/8/1324},
urldate = {2024-10-30},
abstract = {At high frequency, AC resistance of a printed circuit board (PCB) winding becomes important and accounts for a large proportion of planar transformer losses. The winding is then influenced by both skin and proximity phenomenon, which makes the current distribution uneven resulting in an increased resistance. The study of improving AC resistance of a PCB winding has been tackled by many researchers. However, the lack of an overview and comparison among improvements has made it difficult to apply those methods to a specific winding. To overcome the above limitations, this paper investigates the pros and cons of three popular AC resistance optimizing methods: optimizing track width of a solid PCB winding, using multi-strands and using Litz style PCB winding. To verify the theoretical analysis, a total of 12 PCBs are simulated by finite element (FEM) and tested in the laboratory. Five criteria are analyzed, including skin resistance, proximity resistance, AC to DC ratio, total AC resistance and complexity are taken into consideration. The results of this study show that optimizing track width method has a significant improvement on AC resistance while the use of Litz PCB is effective for applications that need stable AC resistance in a wide frequency range. The use of parallel strands winding should be carefully considered as there is not significant benefit in both reducing the AC resistance and AC to DC ratio.},
langid = {english},
file = {/home/jaseg/Sync/Research/Zotero/2020_Nguyen_Fortin Blanchette_A Review and Comparison of Solid, Multi-Strands and Litz Style PCB Winding.pdf}
}
@incollection{nielsenNewApproachPractical2012,
title = {A {{New Approach}} to {{Practical Active-Secure Two-Party Computation}}},
booktitle = {Advances in {{Cryptology}} – {{CRYPTO}} 2012},
@ -3477,6 +3669,16 @@
file = {/home/jaseg/Zotero/storage/WTJ3HBFT/o0485.html}
}
@book{querfurthCoilWindingDescription1954,
title = {Coil {{Winding}}: {{A Description}} of {{Coil Winding Procedures}}, {{Winding Machines}} and {{Associated Equipment}}},
author = {Querfurth, William},
date = {1954},
publisher = {G. Stevens Mfg. Company},
url = {https://vintagewindings.com/gen%20pop/8299543VW8335/TransDesign%201/Coil%20Winding.pdf},
urldate = {2024-10-30},
file = {/home/jaseg/Zotero/storage/MJR5J958/Coil Winding.pdf}
}
@article{RenesasRA6T1Group,
title = {Renesas {{RA6T1 Group User}}'s {{Manual}}: {{Hardware}}},
langid = {english},
@ -3774,6 +3976,25 @@
file = {/home/jaseg/Sync/Research/Zotero/Selmke et al_2022_On the application of Two-Photon Absorption for Laser Fault Injection attacks.pdf}
}
@article{senOrigamiInductorFoldable2024,
title = {Origami {{Inductor}}: {{Foldable}} 3-{{D Polyhedron Multiphase Air-Coupled Inductors With Flux Cancellation}} and {{Faster Transient}}},
shorttitle = {Origami {{Inductor}}},
author = {Sen, Tanuj and Elasser, Youssef and Chen, Minjie},
date = {2024-06},
journaltitle = {IEEE Transactions on Power Electronics},
volume = {39},
number = {6},
pages = {7312--7328},
issn = {1941-0107},
doi = {10.1109/TPEL.2024.3374572},
url = {https://ieeexplore.ieee.org/document/10462531/?arnumber=10462531},
urldate = {2024-10-30},
abstract = {Traditional air-coupled inductors are usually limited to two phases. This article presents the concept of multiphase 3-D polyhedron air-coupled inductors – termed “origami inductors” – formed by folding planar windings on modular surfaces into symmetric 3-D structures, which enables symmetric air-coupling of more than two phases. The air-coupled origami inductors, unlike traditional multiphase coupled inductors, do not need a magnetic core and can operate at high frequencies. Compared to discrete air-core inductors, the origami inductors can be easily transported and assembled and can offer reduced size, smaller current ripple, and faster transient due to dc and ac flux cancellation. Models are developed to quantify the performance benefits of the origami inductor. A tetrahedron-shaped four-phase origami inductor was designed and through FEM simulations, its reduced volume was verified. The origami inductor was also tested as a part of a 5 V input, 12 V output, 80 W four-phase interleaved dc–dc boost converter, switching between frequencies ranging from 1 to 5 MHz, to verify its operational effectiveness.},
eventtitle = {{{IEEE Transactions}} on {{Power Electronics}}},
keywords = {Air-coupled inductor,Analytical models,Atmospheric modeling,dc–dc converter,inductance dual model,Inductors,Integrated circuit modeling,interleaving,magnetic circuit model,multiphase,origami,permeance-capacitor model,polyhedron,Semiconductor device modeling,Solid modeling,Windings},
file = {/home/jaseg/Sync/Research/Zotero/2024_Sen et al_Origami Inductor.pdf;/home/jaseg/Zotero/storage/35VMZ29J/10462531.html}
}
@article{shenDAENetMakingStrong2022,
title = {{{DAENet}}: {{Making Strong Anonymity Scale}} in a {{Fully Decentralized Network}}},
shorttitle = {{{DAENet}}},
@ -3943,6 +4164,24 @@
file = {/home/jaseg/Sync/Research/Zotero/2021_Sozio et al_Patchable Hardware Security Module (PHaSM) for Extending FPGA Root-of-Trust.pdf;/home/jaseg/Zotero/storage/D5BLNRV7/9707698.html}
}
@article{sproHighVoltageInsulationDesign2021,
title = {High-{{Voltage Insulation Design}} of {{Coreless}}, {{Planar PCB Transformers}} for {{Multi-MHz Power Supplies}}},
author = {Spro, Ole Christian and Mauseth, Frank and Peftitsis, Dimosthenis},
date = {2021-08},
journaltitle = {IEEE Transactions on Power Electronics},
volume = {36},
number = {8},
pages = {8658--8671},
issn = {1941-0107},
doi = {10.1109/TPEL.2021.3049353},
url = {https://ieeexplore.ieee.org/document/9314282/?arnumber=9314282},
urldate = {2024-10-30},
abstract = {This article investigates the insulation design for printed, planar, coreless, and high-frequency transformers with high isolation-voltage. By using finite element analysis on 2-D axial-symmetry, the transformer circuit parameters and electric field distribution are modeled and estimated. Several transformers are designed for an operating frequency of 6.78 MHz. The high frequency, coreless design allows for using thicker insulation material while ensuring a high transformer efficiency. The inclusion of the coupling capacitance in the design optimization results in several design solutions with the same figure of merit, but with different footprint and isolation voltages. Moreover, high electric fields are identified around the sharp edges of the printed circuit board (PCB) windings. Finally, the electrical and isolation performance is verified experimentally. The measured electrical properties are close to the simulated values, validating the chosen model. Breakdown tests demonstrate the feasibility of isolation voltage levels up to several tens of kilovolts. The majority of breakdowns occurs at the outer edge of the PCB winding that was identified as a high-field area. Additionally, a concept for grading the electric field of PCB windings is also proposed. Based on the results, the design aspects are discussed in detail for planar, high-frequency isolation transformers with medium-voltage isolation level.},
eventtitle = {{{IEEE Transactions}} on {{Power Electronics}}},
keywords = {Capacitance,Couplings,Design methodology,dielectric breakdown,insulation,Insulation,Power supplies,Power transformer insulation,resonant power conversion,Transformer cores,transformers,Windings},
file = {/home/jaseg/Sync/Research/Zotero/2021_Spro et al_High-Voltage Insulation Design of Coreless, Planar PCB Transformers for.pdf;/home/jaseg/Zotero/storage/I2H9EHKJ/9314282.html}
}
@book{struttVerstarkerUndEmpfanger1951,
title = {Verstärker Und {{Empfänger}}},
author = {Strutt, M. J. O.},
@ -4589,6 +4828,24 @@
file = {/home/jaseg/Zotero/storage/SXDU6E5J/Zhang et al. - 2017 - DolphinAttack Inaudible Voice Commands.pdf}
}
@article{zhangEnergyEncryptionWireless2015,
title = {Energy {{Encryption}} for {{Wireless Power Transfer}}},
author = {Zhang, Zhen and Chau, K. T. and Qiu, Chun and Liu, Chunhua},
date = {2015-09},
journaltitle = {IEEE Transactions on Power Electronics},
volume = {30},
number = {9},
pages = {5237--5246},
issn = {1941-0107},
doi = {10.1109/TPEL.2014.2363686},
url = {https://ieeexplore.ieee.org/document/6928497/?arnumber=6928497},
urldate = {2024-11-07},
abstract = {This paper presents a novel energy encryption strategy for wireless power transfer (WPT) systems, which can effectively improve the security performance of wirelessly transferred energy. In a WPT system, energy is expected to transfer to specific receptors as well as to switch off other unauthorized energy transmission channels, so the security of energy transmission is an important issue. In the proposed secure WPT system, the energy is encrypted by chaotically regulating the frequency of the power source. Then, the authorized receptor can receive the energy by simultaneously adjusting the circuit to decrypt the encrypted energy based on the security key obtained from the power supply, while the unauthorized receptor cannot receive the energy without knowledge of the security key. Hence, a secure energy transmission channel is established to effectively prevent unauthorized receptors from stealing the energy. In this paper, both simulation and experimental results are provided to verify the validity of the proposed encrypted WPT system.},
eventtitle = {{{IEEE Transactions}} on {{Power Electronics}}},
keywords = {Capacitors,Chaos,Coils,Contactless charging,Couplings,Encryption,energy encryption,magnetic resonant coupling (MRC),security,Wireless communication,wireless power transmission (WPT)},
file = {/home/jaseg/Sync/Research/Zotero/Zhang et al_2015_Energy Encryption for Wireless Power Transfer.pdf;/home/jaseg/Zotero/storage/AYSH2G8F/6928497.html}
}
@article{zhangLargeScaleQuantum2018,
title = {Large Scale Quantum Key Distribution: Challenges and Solutions [{{Invited}}]},
shorttitle = {Large Scale Quantum Key Distribution},
@ -4641,6 +4898,40 @@
file = {/home/jaseg/Sync/Research/Zotero/Zhang et al_2015_Robust counterfeit PCB detection exploiting intrinsic trace impedance variations.pdf;/home/jaseg/Zotero/storage/GS9H6QT9/7116294.html}
}
@inproceedings{zhangRobustCounterfeitPCB2015a,
title = {Robust Counterfeit {{PCB}} Detection Exploiting Intrinsic Trace Impedance Variations},
booktitle = {2015 {{IEEE}} 33rd {{VLSI Test Symposium}} ({{VTS}})},
author = {Zhang, Fengchao and Hennessy, Andrew and Bhunia, Swarup},
date = {2015-04},
pages = {1--6},
issn = {2375-1053},
doi = {10.1109/VTS.2015.7116294},
url = {https://ieeexplore.ieee.org/document/7116294/?arnumber=7116294},
urldate = {2024-10-31},
abstract = {The long and distributed supply chain of printed circuit boards (PCBs) makes them vulnerable to different forms of counterfeiting attacks. Existing chip-level integrity validation approaches cannot be readily extended to PCB. In this paper, we address this issue with a novel PCB authentication approach that creates robust, unique signatures from a PCB based on process-induced variations in its trace impedances. The approach comes at virtually zero design and hardware overhead and can be applied to legacy PCBs. Experiments with two sets of commercial PCBs as well as a set of custom designed PCBs show that the proposed approach can obtain unique authentication signature with inter-PCB hamming distance of 47.94\% or higher.},
eventtitle = {2015 {{IEEE}} 33rd {{VLSI Test Symposium}} ({{VTS}})},
keywords = {Authentication,Copper,Counterfeiting,Electrical resistance measurement,High definition video,Impedance,Impedance measurement,Piracy,Printed Circuit Board (PCB),Probes,PUF,Trust},
file = {/home/jaseg/Sync/Research/Zotero/Zhang et al_2015_Robust counterfeit PCB detection exploiting intrinsic trace impedance variations2.pdf;/home/jaseg/Zotero/storage/9M243M47/7116294.html}
}
@article{zhangWirelessPowerTransfer2019,
title = {Wireless {{Power Transfer}}—{{An Overview}}},
author = {Zhang, Zhen and Pang, Hongliang and Georgiadis, Apostolos and Cecati, Carlo},
date = {2019-02},
journaltitle = {IEEE Transactions on Industrial Electronics},
volume = {66},
number = {2},
pages = {1044--1058},
issn = {1557-9948},
doi = {10.1109/TIE.2018.2835378},
url = {https://ieeexplore.ieee.org/document/8357386/?arnumber=8357386},
urldate = {2024-11-07},
abstract = {Due to limitations of low power density, high cost, heavy weight, etc., the development and application of battery-powered devices are facing with unprecedented technical challenges. As a novel pattern of energization, the wireless power transfer (WPT) offers a band new way to the energy acquisition for electric-driven devices, thus alleviating the over-dependence on the battery. This paper presents an overview of WPT techniques with emphasis on working mechanisms, technical challenges, metamaterials, and classical applications. Focusing on WPT systems, this paper elaborates on current major research topics and discusses about future development trends. This novel energy transmission mechanism shows significant meanings on the pervasive application of renewable energies in our daily life.},
eventtitle = {{{IEEE Transactions}} on {{Industrial Electronics}}},
keywords = {Batteries,Capacitive coupled power transfer (CCPT),contactless charging,Couplings,dynamic charging,Electromagnetic interference,Impedance,inductive power transfer (IPT),Integrated circuit modeling,Load modeling,overview,Wireless power transfer,wireless power transfer (WPT)},
file = {/home/jaseg/Sync/Research/Zotero/Zhang et al_2019_Wireless Power Transfer—An Overview.pdf;/home/jaseg/Zotero/storage/MHMC3VK4/8357386.html}
}
@online{zhaoDesignOptimizationLitzWire2023,
title = {Design and {{Optimization}} of {{Litz-Wire Planar Spiral Coil}} for {{Inductive Power Transfer Application}}},
author = {Zhao, Weihao and Peng, Yingzhou and Zhan, Shen and Wang, Huai},

138
paper/paper.tex
View file

@ -44,36 +44,44 @@ Achieving Rotation-Invariant Coupling using Multi-Layer PCB Inductors}
\section{Introduction}
Inductive wireless power transfer (WPT) is a widely used technology supported by a large corpus of research literature.
% FIXME cite
While working on a novel application of Inductive wireless power transfer in a Inertial Hardware Security Module (IHSM)
as proposed by Götte and Scheuermann, % FIXME cite
we found ourselves presented with an unusual set of constraints around inductive wireless power transfer through a
rotating joint using a PCB inductor that does not yet seem to be addressed adequately in the existing literature on
inductive wireless power transfer.
Inductive Wireless Power Transfer (WPT) is a widely used technology supported by a large corpus of research literature
\cite{awuahNovelCoilDesign2023, batraEffectFerriteAddition2015, curranModelingCharacterizationPCB2015,
fanSimultaneousWirelessPower2024, leeSimpleWirelessPower2017, liWirelessPowerTransfer2015,
maierContributionSystemDesign2019, mooreApplicationsWirelessPower2019, mouEnergyEfficientAdaptiveDesign2017,
mouWirelessPowerTransfer2015, mullenEffectMisalignmentInductive, rezmeritaSelfMutualInductance2017,
zhangWirelessPowerTransfer2019}.
While working on a novel application of Inductive WPT in a Inertial Hardware Security Module (IHSM) as previously
published in\textcite{gotteCantTouchThis2022}, we found ourselves presented with an unusual set of constraints
attempting WPT through a rotating joint using a PCB inductor---a set of constraints that does not yet seem to be
addressed adequately in the existing literature on inductive WPT.
Our application poses the challenge of transferring power between a stationary and a rotating part. To reduce
manufacturing cost of both parts, and to reduce weight, and thereby inertia as well as susceptibility to vibration in
the rotating part, we decided to use inductors that are directly patterned onto the IHSM's printed circuit boards.
The primary constraint that results from this choice is a highly constrained turn count that is limited by the PCB
manufacturing processes' pattern resolution and by ohmic heating.
Our application poses the challenge of transferring power between a stationary and a rotating part of an
IHSM\cite{gotteCantTouchThis2022} through a pair of WPT inductors located on the IHSM's axis of rotation. To reduce
manufacturing cost of both parts, and to reduce weight and thereby inertia as well as susceptibility to vibration in the
rotating part, we decided to use inductors that are directly patterned onto the IHSM's printed circuit boards. The
primary constraint that results from this choice is that the PCB manufacturing processes' pattern resolution results in
a strict upper limit to the turn count that can be achieved in an inductor with a given area.
We found that the limited turn count of PCB inductors results in a \emph{slightly} asymmetric field, which means that
the coupling coefficient of two such inductors oscillates at one oscillation per revolution when the inductors are
rotated on-axis, even if both inductors are perfectly coaxially aligned.
We found that at such small turn counts, a simple spiral PCB inductors exhibits a \emph{slightly} asymmetric field,
which means that the coupling coefficient of two such inductors oscillates at one cycle per revolution when the
inductors are rotated on-axis, even if both inductors are perfectly coaxially aligned.
In other inductive wireless power transfer systems, this oscillation is mitigated by one of several factors: First, for
this effect to matter in the first place, the two coils have to be rotating with respect to one another. In ferrite or
iron-cored inductors, the core shapes the magnetic field and evens out any such imperfection. In wire-wound inductors,
the (much) higher turn count and circular aspect ratio of the wires reduces this effect to almost nothing. Finally, the
output ripple caused by this oscillation can be filtered through a voltage regulator or by using a large decoupling
capacitor on the secondary side.
iron-cored inductors, the core is the single major factor shaping the magnetic field, and evens out any small effect
asymmetric windings might have. In wire-wound inductors, the often higher turn count and the tightly packed, circular
wires reduce this effect to almost nothing. Finally, the output ripple caused by this oscillation can be filtered
through a voltage regulator or by using a large decoupling capacitor on the secondary side where those components can be
accomodated on the rotating part given the centrifugal forces resulting from a concrete design's rate of rotation.
While there exist a number of prior works focusing on efficient power transfer between two coils whose position relative
to one another cannot be precisely controlled as is the case in wireless phone charging systems, it is generally assumed
that the two coils remain (almost) stationary with respect to one another throughout the charging process. % FIXME cite
While there exist a corpus of prior work focusing on efficient power transfer between two coils whose position relative
to one another cannot be precisely controlled as is the case in wireless phone charging systems as well as in proposed
WPT electric vehicle charges,
% TODO cite
it is generally assumed that the two coils remain (almost) stationary with respect to one another.
There exists a small body of work on inductive power transfer through rotating joints, % FIXME cite
There exists a small body of work on inductive power transfer through rotating
joints\cite{fanSimultaneousWirelessPower2024},
but here the focus lies on higher power budgets than our application requires, which often requires ferrite or iron-core
inductors.
@ -81,27 +89,42 @@ Our application is unique in that it requires power transfer through a joint tha
while we simultaneously want to avoid heavy components on the (rotating) receiver side. (Liquid) electrolytic capacitors
cannot be used due to the large centrifugal acceleration that the rotating part experiences, and other heavy components
such as large ceramic or polymer electrolytic capacitors or ferrite-core power inductors are inadvisable since they will
exert large stresses onto the assembly due to the same centrifugal acceleration, and any imbalance caused by tolerances
in the placement of heavy components will quickly cause a strong vibration.
exert large stresses onto their solder joints and the surrounding assembly due to the same centrifugal acceleration.
Any imbalance caused by tolerances in the placement of heavy components or the precise shape of their solder fillets
can cause detrimental vibration.
\subsection{Twisted inductors}
Applying a principle inspired by rectangular or octagonal RFIC inductor design as well as by the polygonal basket-woven
air coils used in early radio sets, we propose a novel way of laying out circular PCB inductors that twists the
inductor's windings around one another using a ring of vias each on the inside and outside of the inductor's windings.
Applying some math, we show that we can layout a twisted inductor for any number of twists that is co-prime to the
inductor's turn count.
To solve this conundrum, we applied a principle inspired by rectangular or octagonal RFIC inductor design as well as by
the polygonal basket-woven air coils used in early radio sets. In this paper, we propose a novel way of laying out
circular PCB inductors that twists the inductor's windings around one another using a ring of vias each on the inside
and outside of the inductor's windings. Applying some math, we show that we can layout a twisted inductor for any number
of twists that is co-prime to the inductor's turn count, and that in fact, our approach opens up a large design space
for inductor layouts that interpolate between planar spiral inductors on one end, and planar toroidal inductors on the
other end. Our approach thus generalizes a number of previous approaches to the design of planar inductors.
We observe that in high-frequency applications, a moderate number of twists increases the spacing between the beginning
and end of the inductor's conductor, where the majority of the inductor's AC current flows. This decreases the parasitic
capacitance of the inductor and raises its self-resonant frequency, raising its maximum possible operating frequency and
improving its efficiency at lower operating frequencies. This is the same effect that is exploited in basket-woven
air core inductors that were commonly used in old radio sets.
improving its efficiency at lower operating frequencies. We note that the principle behind this reduction in distributed
capacitance coincides with the intuition that led to the creation of honeycomb or basket-woven inductors in early radio
sets more than a hundred years ago, before the invention of ferrites.
\subsection{Contributions}
In this paper, we introduce twisted inductors, a novel technique of laying out planar inductors that both improves
rotational symmetry in rotating wireless power transfer interface as well as quality factor in other applications. We
provide detailed layout instructions, including a mathematical analysis of the available parameter space and an
analytical model of both inductance and DC equivalent series resistance of our scheme. Validating our scheme, we provide
laboratory measurements of the basic parameters of a number of test specimens comparing our scheme to conventional
techniques. We furhter performed a number of FEM simulations to validate our inductance and ESL approximations. Finally,
to analyze the degree of rotational symmetry in our proposed scheme, we provide the results of a large number of
automated measurements of coupling between pairs of inductors under various rotations, offsets, distances and load
conditions.
\section{Related Work}
% TODO cite \cite{fanSimultaneousWirelessPower2024} (rotating coupling)
% TODO cite \cite{mullenEffectMisalignmentInductive} (misaligned coils)
% TODO cite fanSimultaneousWirelessPower2024 below (rotating joint)
% TODO cite \cite{mullenEffectMisalignmentInductive} below (misaligned coils)
\subsection{A Short Historical Diversion on Basket-Woven Air Coils}
@ -111,10 +134,12 @@ wireless telegraphy after the turn of the twentieth century, coils with high ind
of both transmitters and receivers, but the ferrites that would later permit their compact construction were still being
developed. The ferromagnetic core material of choice back then was laminated iron, which was only useful at low
frequencies due to eddy current losses. As a result, the inductors in radio circuits of the era were constructed as
air-core coils. While air core inductors are immune to core saturation, the poor magnetic permeability of air leads
necessitates many large turns of wire for practical inductance values, which for reasons of practicality or leakage
inductance often could not be wound in a single layer. Winding an inductor with many turns on multiple layers improves
compactness and leakage inductance, but in turn gives rise to increased distributed capacitance.
air-core coils. While air core inductors are immune to core saturation, the poor magnetic permeability of air
necessitates a large number of wide turns of wire to reach useful inductance values, which for reasons of practicality
or leakage inductance often could not be wound as a single layer cylindrical coil. This could be resolved by winding an
inductor with many turns on multiple layers, which improves compactness and leakage inductance, but this in turn gives
rise to increased distributed capacitance as now turns with a large voltage differential are layered right on top of
each other.
Back then, a number of ways were devised to decrease distributed capacitance in multilayer inductors. These methods can
be divided into two general categories: Optimizing the connecting order of turns to minimize the voltage differential
@ -125,7 +150,7 @@ connecting adjacent turns in a diagonal zigzag pattern. Then as now, wound induc
feasible to manufacture reliably by machine, but the technique can be closely replicated in PCB inductors as shown in
\textcite{leePrintedSpiralWinding2011a}. The main limiting factors in a PCB implementation are the requirement for a
large number of vias inside the inductor's turns limiting the achievable turn count\footnote{In PCBs, as opposed to
ICs, vias limit the achievablie turn count when they need to be placed in-line inside the turns as opposed to on the
ICs, vias limit the achievable turn count when they need to be placed in-line inside the turns as opposed to on the
inside or outside because a PCB's minimum trace/space widths are usually much smaller than the smallest feasible via,
consisting of a minimum-size drill surrounded by a minimum-size annular ring.} and increasing ESR through the thin trace
sections that are necessary to accomodate the via structure, as well as the layer pairing limitations when blind vias
@ -159,25 +184,24 @@ layer of such windings forms a helix whose pitch is equal to the wire diameter.
helical scheme reversing at the coil ends, but uses a helical pitch larger than the wire diameter to form a structure
similar to a spool of sewing thread.
Examples of honeycomb and basket woven coils from contemporary literature are shown in Figure\
\ref{fig_illust_honeycomb_basket}. In a honeycomb coil, like in an universal winding subsequent winding layers are wound
at a criss-cross pattern. The characteristic feature of honeycomb coils is that the winding machine is adjusted to
produce large air gaps between adjacent windings on the same layer. When multiple layers like this are stacked, a
rhomboid pattern results that is vaguely reminiscent of a honeycomb's structure.
Other winding techniques include honeycomb and basket woven coils, some contemporary examples of which are shown in
Figure\ \ref{fig_illust_honeycomb_basket}. In a honeycomb coil, like in an universal winding, subsequent winding layers
are wound at a criss-cross pattern. The characteristic feature of honeycomb coils is that the winding machine is
adjusted to produce large air gaps between adjacent windings on the same layer. When multiple layers like this are
stacked, a three-dimensional rhomboid pattern results that is vaguely reminiscent of a honeycomb's structure.
In basket-woven coils, a mandrel consisting of an odd number of sticks pointing either radially or axially is used, and
the wire is fed woven between adjacent sticks in an alternating direction. While visually similar to honeycomb coils,
this winding technique is more suited to homebrew construction and less amenable to mass production by machine. In
axially basket-woven coils, the mandrel can be pulled out after the coil is finished. Like honeycomb coils, the
resulting structure can be made mechanically stable with some lacquer, with the turns carrying the layers where they
cross.
the wire is woven between adjacent sticks in an alternating direction. While visually similar to honeycomb coils, this
winding technique is more suited to homebrew construction and less amenable to mass production by machine. In axially
basket-woven coils, the mandrel can be pulled out after the coil is finished. Like honeycomb coils, the resulting
structure can be made mechanically stable with some lacquer, with the turns carrying the layers where they cross.
Both construction techniques apply similar principles to those leading to the improved high-frequency behavior of
twisted inductors. Interestingly, both honeycomb and basket-woven coils are also governed by the same coprimality
condition between the number of turns and the number of inversions within each turn that we describe for our twisted
inductors below, although in contemporary literature, this condition is never explicitly stated
\cite{eppenAnforderungenEinzelteileRundfunkempfanger1927, kleinSpulenUndSchwingungskreise1941,
wiggeRundfunktechnischesHandbuch1930}.
twisted inductors that we describe in this paper. Interestingly, the winding schemes of both honeycomb and basket-woven
coils are also governed by the same coprimality condition between the number of turns and the number of inversions
within each turn that we describe for our twisted inductors below, although we could not find an example in contemporary
literature where this condition was explicitly stated \cite{eppenAnforderungenEinzelteileRundfunkempfanger1927,
kleinSpulenUndSchwingungskreise1941, wiggeRundfunktechnischesHandbuch1930, querfurthCoilWindingDescription1954}.
\subsection{PCB inductor design for wireless power transfer}
@ -208,11 +232,11 @@ large air coils exhibit more parasitic capacitance than much smaller ferrite-cor
when implemented in a PCB process a large fraction of the electrical fields responsible for this capacitance pass
through the PCB's substrate, not air. The relative permittivity $\epsilon_r$ of common PCB substrates typically lies in
the range of $4$ to $5$\cite{mumbyDielectricPropertiesFR41989}, which increases the distributed capacitance compared to
a pure air-core inductor.
a pure air-core inductor by approximately that same factor.
\subsection{Twisted Inductors in RFIC Design}
Planar inductors are commonly used in RF ICs. In RFIC design, the major challenges are area optimization, and precisely
Planar inductors are commonly used in RF ICs. In RFIC design, the major challenges are area optimization and precisely
predicting the inductor's characteristics during the design phase. Common optimizations include applying a variable
trace pitch to reduce distributed capacitance\cite{lopez-villegasImprovementQualityFactor2000}, and applying variable
trace width to decrease equivalent series resistance while preserving total inductance and quality
@ -224,7 +248,7 @@ second layer\cite{daneshDifferentiallyDrivenSymmetric2002,martinMultiturnTwisted
in RFIC design is mainly focused on their electrical symmetry, so that the two input ports can be fed with a fully
differential signal, with the inductor loading both driver outputs equally across the inductor's frequency range.
The simplest twisted inductor as shown below with $k=1$ inversion corresponds to the counterwound scheme that is
Setting the inversion count to $k=1$ in our proposed scheme as shown below yields the counterwound scheme that is
commonly used for two-layer planar
inductors\cite{lopeFirstSelfResonant2021,sproHighVoltageInsulationDesign2021,leePrintedSpiralWinding2011a}, and
which has been used to stack planar coils for more than a century\cite{flemingPrinciplesElectricWave1910}.