| 1. |
- Abelev, Betty, et al.
(författare)
-
Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; :11
-
Tidskriftsartikel (refereegranskat)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 2. |
- Crous, Pedro W., et al.
(författare)
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Fungal Planet description sheets: 1383–1435
- 2022
-
Ingår i: Persoonia: Molecular Phylogeny and Evolution of Fungi. - : Naturalis Biodiversity Center. - 0031-5850 .- 1878-9080. ; 48, s. 261-371
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Tidskriftsartikel (refereegranskat)abstract
- Novel species of fungi described in this study include those from various countries as follows: Australia, Agaricus albofoetidus, Agaricus aureoelephanti and Agaricus parviumbrus on soil, Fusarium ramsdenii from stem cankers of Araucaria cunninghamii, Keissleriella sporoboli from stem of Sporobolus natalensis, Leptosphaerulina queenslandica and Pestalotiopsis chiaroscuro from leaves of Sporobolus natalensis, Serendipita petricolae as endophyte from roots of Eriochilus petricola, Stagonospora tauntonensis from stem of Sporobolus natalensis, Teratosphaeria carnegiei from leaves of Eucalyptus grandis × E. camaldulensis and Wongia ficherai from roots of Eragrostis curvula. Canada, Lulworthia fundyensis from intertidal wood and Newbrunswickomyces abietophilus (incl. Newbrunswickomyces gen. nov.) on buds of Abies balsamea. Czech Republic, Geosmithia funiculosa from a bark beetle gallery on Ulmus minor and Neoherpotrichiella juglandicola (incl. Neoherpotrichiella gen. nov.) from wood of Juglans regia. France, Aspergillus rouenensis and Neoacrodontium gallica (incl. Neoacrodontium gen. nov.) from bore dust of Xestobium rufovillosum feeding on Quercus wood, Endoradiciella communis (incl. Endoradiciella gen. nov.) endophytic in roots of Microthlaspi perfoliatum and Entoloma simulans on soil. India, Amanita konajensis on soil and Keithomyces indicus from soil. Israel, Microascus rothbergiorum from Stylophora pistillata. Italy, Calonarius ligusticus on soil. Netherlands, Appendopyricularia juncicola (incl. Appendopyricularia gen. nov.), Eriospora juncicola and Tetraploa juncicola on dead culms of Juncus effusus, Gonatophragmium physciae on Physcia caesia and Paracosmospora physciae (incl. Paracosmospora gen. nov.) on Physcia tenella, Myrmecridium phragmitigenum on dead culm of Phragmites australis, Neochalara lolae on stems of Pteridium aquilinum, Niesslia nieuwwulvenica on dead culm of undetermined Poaceae, Nothodevriesia narthecii (incl. Nothodevriesia gen. nov.) on dead leaves of Narthecium ossifragum and Parastenospora pini (incl. Parastenospora gen. nov.) on dead twigs of Pinus sylvestris. Norway, Verticillium bjoernoeyanum from sand grains attached to a piece of driftwood on a sandy beach. Portugal, Collybiopsis cimrmanii on the base of living Quercus ilex and amongst dead leaves of Laurus and herbs. South Africa, Paraproliferophorum hyphaenes (incl. Paraproliferophorum gen. nov.) on living leaves of Hyphaene sp. and Saccothecium widdringtoniae on twigs of Widdringtonia wallichii. Spain, Cortinarius dryosalor on soil, Cyphellophora endoradicis endophytic in roots of Microthlaspi perfoliatum, Geoglossum laurisilvae on soil, Leptographium gemmatum from fluvial sediments, Physalacria auricularioides from a dead twig of Castanea sativa, Terfezia bertae and Tuber davidlopezii in soil. Sweden, Alpova larskersii, Inocybe alpestris and Inocybe boreogodeyi on soil. Thailand, Russula banwatchanensis, Russula purpureoviridis and Russula lilacina on soil. Ukraine, Nectriella adonidis on overwintered stems of Adonis vernalis. USA, Microcyclus jacquiniae from living leaves of Jacquinia keyensis and Penicillium neoherquei from a minute mushroom sporocarp. Morphological and culture characteristics are supported by DNA barcodes.
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| 3. |
- Ivanisevic, Nikola, 1988-
(författare)
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Circuit Design Techniques for Implantable Closed-Loop Neural Interfaces
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Implantable neural interfaces are microelectronic systems, which have the potential to enable a wide range of applications, such as diagnosis and treatment of neurological disorders. These applications depend on neural interfaces to accurately record electrical activity from the surface of the brain, referred to as electrocorticography (ECoG), and provide controlled electrical stimulation as feedback. Since the electrical activity in the brain is caused by ionic currents in neurons, the bridge between living tissue and inorganic electronics is achieved via microelectrode arrays. The conversion of the ionic charge into freely moving electrons creates a built-in electrode potential that is several orders of magnitude larger than the ECoG signal, which increases the dynamic range, resolution, and power consumption requirements of neural interfaces. Also, the small surface area of microelectrodes implies a high-impedance contact, which can attenuate the ECoG signal. Moreover, the applied electrical stimulation can also interfere with the recording and ultimately cause irreversible damages to the electrodes or change their impedance. This thesis is devoted to resolving the challenges of high-resolution recording and monitoring the electrode impedance in implantable neural interfaces.The first part of this thesis investigates the state-of-the-art neural interfaces for ECoG and identifies their limitations. As a result of the investigation, a high-resolution ADC is proposed and implemented based on a ΔΣ modulator. In order to enhance performance, dynamic biasing and area-efficient switched-capacitor circuits were proposed. The ΔΣ modulator is combined with the analog front-end to provide a complete readout solution for high-resolution ECoG recording. The corresponding chip prototype was fabricated in a 180 nm CMOS process, and the measurement results showed a 14-ENOB over a 300-Hz bandwidth while dissipating 54-μW.The second part of this thesis expands upon the well-known methods for impedance measurements and proposes an alternative digital method for monitoring the electrode-tissue interface impedance. The proposed method is based on the system identification technique from adaptive digital filtering, and it is compatible with existing circuitry for neural stimulation. The method is simple to implement and performs wide-band measurements. The system identification was first verified through behavioral simulations and then tested with a board-level prototype in order to validate the functionality under real conditions. The measurement results showed successful identification of the electrode-electrolyte and electrode-skin impedance magnitudes.
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| 4. |
- Abelev, Betty, et al.
(författare)
-
Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; :7
-
Tidskriftsartikel (refereegranskat)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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| 5. |
- Albertsson, Dagur Ingi, 1993-, et al.
(författare)
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Compact Macrospin-Based Model of Three-Terminal Spin-Hall Nano Oscillators
- 2019
-
Ingår i: IEEE transactions on magnetics. - : IEEE Press. - 0018-9464 .- 1941-0069. ; 55:10
-
Tidskriftsartikel (refereegranskat)abstract
- Emerging spin-torque nano oscillators (STNOs) and spin-Hall nano oscillators (SHNOs) are potential candidates for microwave applications. Recent advances in three-terminal magnetic tunnel junction (MTJ)-based SHNOs opened the possibility to develop more reliable and well-controlled oscillators, thanks to individual spin Hall-driven precession excitation and read-out paths. To develop hybrid systems by integrating three-terminal SHNOs and CMOS circuits, an electrical model able to capture the analog characteristics of three-terminal SHNOs is needed. This model needs to be compatible with current electric design automation (EDA) tools. This work presents a comprehensive macrospin-based model of three-terminal SHNOs able to describe the dc operating point, frequency modulation, phase noise, and output power. Moreover, the effect of voltage-controlled magnetic anisotropy (VCMA) is included. The model shows good agreement with experimental measurements and could be used in developing hybrid three-terminal SHNO/CMOS systems.
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| 6. |
- Albertsson, Dagur Ingi
(författare)
-
Spintronic and Electronic Oscillators for Magnetic Field Sensing and Ising Machines
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Oscillators can exhibit a range of complex dynamics which are often encountered in nature. These characteristics include synchronization, injection locking, chaos, bifurcations, etc. To date, the applications of electronic oscillators has mostly been limited to communication systems. However, in recent years, the possibility of using the rich dynamics of oscillators in unconventional applications, including time-based information processing and computational applications, has been also explored. In this thesis, this potential is investigated using emerging spintronic oscillators and established electronic oscillators. The first part of this thesis targets emerging spintronic oscillators, which exhibit a range of attractive features, including GHz operating frequency, wide tunability and nanoscale size. To explore the potential of these devices, an electrical behavioural model was developed for the promising three-terminal spin-Hall nano-oscillator. The behavioural model is based on the macrospin approximation, which is commonly used to describe the operation principles of spintronic oscillators, and it was implemented in Verilog-A. Moreover, the behavioural model was verified against experimental measurements from literature, demonstrating that the most important characteristics of three-terminal spin-Hall nano-oscillators are accurately captured. Subsequently, two potential applications that could benefit from the unique characteristics of spintronic oscillators were identified and explored. First, a magnetic field sensing system, which takes advantage of the wide frequency tunability of spintronic oscillators as a function of externally applied magnetic field, was proposed and demonstrated. This sensing system, inspired by voltage-controlled oscillator analog-to-digital converters, shows performance similar to the state-of-the-art magnetic field sensors, making it a promising application for spintronic oscillators. Next, the possibility of utilizing spintronic oscillators to realize Ising machines (IMs) was explored and demonstrated with numerical simulations. This was the first-time demonstration of spintronic oscillator-based Ising machines. The numerical simulation results show that spintronic oscillators are a promising device to realize ultra-fast Ising Machines able to solve complex combinatorial optimization problems on nano-second time scale.The second part of the thesis extends on the idea of oscillator-based IMs, but using electronic oscillators. The potential of realizing highly reconfigurable oscillator-based IMs based on quasiperiodically modulated coupling was explored. The advantages and potential challenges associated with this approach were highlighted, and a proof-of-concept IM using CMOS ring oscillators was proposed and simulated. Finally, a completely new type of IMs based on bifurcations in a network of coupled Duffing oscillators was proposed and developed. This work highlights a new research direction based on using dynamical systems implemented with analog circuits to realize IMs.
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| 7. |
- Atallah, Jad. G., et al.
(författare)
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A direct conversion WiMAX RF receiver front-end in CMOS technology
- 2007
-
Ingår i: ISSCS 2007. - NEW YORK : IEEE. - 9781424409686 ; , s. 37-40
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a direct conversion RF receiver front-end supporting the WiMAX standard. The front-end is implemented in 0.18um CMOS technology and designed using the ARCHER software. It shows how the design flow can be accelerated starting from the standard specifications and going down to schematics. All this is accompanied by test benches to extract the relevant metrics. This front-end provides a total gain of 31dB, a noise figure of 3.3dB, an IIP2 of 49.5dBm, and an IIP3 of -13.8dBm.
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| 8. |
- Chaourani, Panagiotis, 1989-, et al.
(författare)
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A Study on Monolithic 3-D RF/AMS ICs: Placing Digital Blocks Under Inductors
- 2018
-
Ingår i: IEEE SOI-3D-Subthreshold Microelectronics Technology Unified Conference (S3S). - : IEEE conference proceedings.
-
Konferensbidrag (refereegranskat)abstract
- The placement of bottom tier blocks under top-tierinductors could significantly improve the area-efficiency of M3DRF/AMS circuits, paving the way for new applications of thisintegration technology. This work investigates the potential ofplacing digital blocks in the bottom tier, underneath top tierinductors. A design-technology co-optimization flow is appliedand a number of design guidelines are suggested. These guidelinesensure high electromagnetic isolation between the two tiers, withminimum penalties on the loading of bottom tier wires, as wellas on the inductor’s performance.
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| 9. |
- Chaourani, Panagiotis, 1989-, et al.
(författare)
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Enabling Area Efficient RF ICs through Monolithic 3D Integration
- 2017
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Ingår i: Proceedings of the 2017 Design, Automation and Test in Europe, DATE 2017. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783981537093 ; , s. 610-613
-
Konferensbidrag (refereegranskat)abstract
- The Monolithic 3D (M3D) integration technology has emerged as a promising alternative to dimensional scaling thanks to the unprecedented integration density capabilities and the low interconnect parasitics that it offers. In order to support technological investigations and enable future M3D circuits, M3D design methodologies, flows and tools are essential. Prospective M3D digital applications have attracted a lot of scientific interest. This paper identifies the potential of M3D RF/analog circuits and presents the first attempt to demonstrate such circuits. Towards this, a M3D custom design platform, which is fully compatible with commercial design tools, is proposed and validated. The design platform includes process characteristics, device models, LVS and DRC rules and a parasitic extraction flow. The envisioned M3D structure is built on a commercial CMOS process that serves as the bottom tier, whereas a SOI process is used as top tier. To validate the proposed design flow and to investigate the potential of M3D RF/analog circuits, a RF front-end design for Zig-Bee WPAN applications is used as case-study. The M3D RF front-end circuit achieves 35.5 % area reduction, while showing similar performance with the original 2D circuit.
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| 10. |
- Chaourani, Panagiotis, et al.
(författare)
-
Inductors in a Monolithic 3-D Process : Performance Analysis and Design Guidelines
- 2019
-
Ingår i: IEEE Transactions on Very Large Scale Integration (vlsi) Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1063-8210 .- 1557-9999. ; 27:2, s. 468-480
-
Tidskriftsartikel (refereegranskat)abstract
- Monolithic 3-D (M3D) integration technology has demonstrated significant area reduction in digital systems. Recently, its applications to other fields have been considered as well. To fully investigate the potential of M3D for radio-frequency/analog-mixed signal (RF/AMS) circuits and systems, the behavior of inductors in this technology needs to be evaluated. Toward this, in this paper, the effect of M3D integration on their inductance densities and quality factors has been analyzed. The impact of shields on M3D inductors has been investigated, as well as the shunting of multiple metal layers to form multimetal inductors. In an attempt to improve the area efficiency of M3D RF/AMS circuits, the potential of placing bottom-tier blocks underneath top-tier inductors has been identified, and a set of guidelines has been proposed to maximize the inter-tier electromagnetic isolation. These guidelines deal with the suitable position of both low- and high-frequency blocks, their wiring, as well as the type of shield that is needed between them and the inductors. To prove the efficiency of these guidelines, an array of bottom-tier resistors has been placed underneath a top-tier inductor, resulting in more than 50 dB of inter-tier isolation for frequencies up to 20 GHz.
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| 11. |
- Chaourani, Panagiotis, 1989-
(författare)
-
Sequential 3D Integration - Design Methodologies and Circuit Techniques
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sequential 3D (S3D) integration has been identified as a potential candidate for area efficient ICs. It entails the sequential processing of tiers of devices, one on top the other. The sequential nature of this processing allows the inter-tier vias to be processed like any other inter-metal vias, resulting in an unprecedented increase in the density of vertical interconnects. A lot of scientific attention has been directed towards the processing aspects of this 3-D integration approach, and in particular producing high-performance top-tier transistors without damaging the bottom tier devices and interconnects.As far as the applications of S3D integration are concerned, a lot of focus has been placed on digital circuits. However, the advent of Internet-of-Things applications has motivated the investigation of other circuits as well.As a first step, two S3D design platforms for custom ICs have been developed, one to facilitate the development of the in-house S3D process and the other to enable the exploration of S3D applications. Both contain device models and physical verification scripts. A novel parasitic extraction flow for S3D ICs has been also developed for the study of tier-to-tier parasitic coupling.The potential of S3D RF/AMS circuits has been explored and identified using these design platforms. A frequency-based partition scheme has been proposed, with high frequency blocks placed in the top-tier and low-frequency ones in the bottom. As a proof of concept, a receiver front-end for the ZigBee standard has been designed and a 35% area reduction with no performance trade-offs has been demonstrated.To highlight the prospects of S3D RF/AMS circuits, a study of S3D inductors has been carried out. Planar coils have been identified as the most optimal configuration for S3D inductors and ways to improve their quality factors have been explored. Furthermore, a set of guidelines has been proposed to allow the placement of bottom tier blocks under top-tier inductors towards very compact S3D integration. These guidelines take into consideration the operating frequencies and type of components placed in the bottom tier.Lastly, the prospects of S3D heterogeneous integration for circuit design have been analyzed with the focus lying on a Ge-over-Si approach. Based on the results of this analysis, track-and-hold circuits and digital cells have been identified as potential circuits that could benefit the most from a Ge-over-Si S3D integration scheme, thanks to the low on-resistance of Ge transistors in the triode region. To improve the performance of top-tier Ge transistors, a processing flow that enables the control of their back-gates has been also proposed, which allows controlling the threshold voltage of top-tier transistors a truntime.
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| 12. |
- Chen, Tingsu, et al.
(författare)
-
A 2 GHz - 8.7 GHz Wideband Balun-LNA with Noise Cancellation and Gain Boosting
- 2012
-
Ingår i: PRIME 2012: Proceedings of the 8th Coference on Ph.D. Research in Microelectronics and Electronics, 2012. - : IEEE conference proceedings. - 9783800734429 ; , s. 59-62
-
Konferensbidrag (refereegranskat)abstract
- A wideband Balun-LNA covering the operation frequency range of magnetic tunnel junction Spin Torque Oscillator is presented. The LNA is a combination of common-source and cross-coupled common-gate stages, which provides wideband matching and noise cancellation, as well as gain boosting. The internal feedback introduced by the cross-coupling allows an additional degree of freedom to select transistor sizes and bias by decoupling the impedance matching, noise, and gain imbalance trade-offs which are present in similar topologies. Two LNAs using the proposed technique are designed in 65nm CMOS. The LNAs have a simulated bandwidth of 2 GHz - 8.7 GHz, gain of 16 dB, IIP3 of -3.5 dBm, and NF < 3.8 dB while consuming 3.72 mW from a 1.2 V power supply.
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| 13. |
- Chen, Tingsu, et al.
(författare)
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A highly tunable microwave oscillator based on MTJ STO technology
- 2014
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Ingår i: Microwave and optical technology letters (Print). - : Wiley. - 0895-2477 .- 1098-2760. ; 56:9, s. 2092-2095
-
Tidskriftsartikel (refereegranskat)abstract
- This article presents a fully ESD-protected, highly tunable microwave oscillator based on magnetic tunnel junction (MTJ) spin torque oscillator (STO) technology. The oscillator consists of a compact MTJ STO and a 65 nm CMOS wideband amplifier, which amplifies the RF signal of the MTJ STO to a level that can be used to drive a PLL. The (MTJ STO+amplifier IC) pair shows a measured quality factor (Q) of 170 and a wide tunability range from 3 to 7 GHz, which demonstrate its potential to be used as a microwave oscillator in multiband, multistandard radios.
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| 14. |
- Chen, Tingsu, 1987-, et al.
(författare)
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An Inductorless Wideband Balun-LNA for Spin Torque Oscillator-based Field Sensing
- 2014
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Ingår i: Electronics, Circuits and Systems (ICECS), 2014 21st IEEE International Conference on. - : IEEE conference proceedings. - 9781479942435 ; , s. 36-39
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a wideband inductorless Balun-LNA targeting spin torque oscillator-based magnetic field sensing applications. The LNA consistsof a CS stage combined with a cross-coupled CG stage, which offers wideband matching, noise/distortion cancellation and gain boosting, simultaneously. The Balun-LNA is implemented in a 65 nm CMOS technology, and it is fully ESD-protected and packaged. Measurement results show a bandwidth of 2 GHz - 7 GHz, a voltage gain of 20 dB, an IIP3 of +2 dBm, and a maximum NF of 5 dB. The LNA consumes 3.84 mW from a 1.2 V power supply and occupies a total silicon area of 0.0044 mm2. The measurement results demonstrate that the proposed Balun-LNA is highly suitable for the STO-based field sensing applications.
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| 15. |
- Chen, Tingsu, et al.
(författare)
-
Comprehensive and Macrospin-Based Magnetic Tunnel Junction Spin Torque Oscillator Model-Part I : Analytical Model of the MTJ STO
- 2015
-
Ingår i: IEEE Transactions on Electron Devices. - 0018-9383 .- 1557-9646. ; 62:3, s. 1037-1044
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic tunnel junction (MTJ) spin torque oscillators (STOs) have shown the potential to be used in a wide range of microwave and sensing applications. To evaluate the potential uses of MTJ STO technology in various applications, an analytical model that can capture MTJ STO's characteristics, while enabling system-and circuit-level designs, is of great importance. An analytical model based on macrospin approximation is necessary for these designs since it allows implementation in hardware description languages. This paper presents a new macrospin-based, comprehensive, and compact MTJ STO model, which can be used for various MTJ STOs to estimate the performance of MTJ STOs together with their application-specific integrated circuits. To adequately present the complete model, this paper is divided into two parts. In Part I, the analytical model is introduced and verified by comparing it against measured data of three different MTJ STOs, varying the angle and magnitude of the magnetic field, as well as the DC biasing current. The proposed analytical model is suitable for being implemented in Verilog-A and used for efficient simulations at device, circuit, and system levels. In Part II, the full Verilog-A implementation of the analytical model with accurate phase noise generation is presented and verified by simulations.
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| 16. |
- Chen, Tingsu, et al.
(författare)
-
Comprehensive and Macrospin-Based Magnetic Tunnel Junction Spin Torque Oscillator Model-Part II : Verilog-A Model Implementation
- 2015
-
Ingår i: IEEE Transactions on Electron Devices. - 0018-9383 .- 1557-9646. ; 62:3, s. 1045-1051
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Tidskriftsartikel (refereegranskat)abstract
- The rapid development of the magnetic tunnel junction (MTJ) spin torque oscillator (STO) technology demands an analytical model to enable building MTJ STO-based circuits and systems so as to evaluate and utilize MTJ STOs in various applications. In Part I of this paper, an analytical model based on the macrospin approximation has been introduced and verified by comparing it with the measurements of three different MTJ STOs. In Part II, the full Verilog-A implementation of the proposed model is presented. To achieve a reliable model, an approach to reproducing the phase noise generated by the MTJ STO has been proposed and successfully employed. The implemented model yields a time domain signal, which retains the characteristics of operating frequency, linewidth, oscillation amplitude, and DC operating point, with respect to the magnetic field and applied DC current. The Verilog-A implementation is verified against the analytical model, providing equivalent device characteristics for the full range of biasing conditions. Furthermore, a system that includes an MTJ STO and CMOS RF circuits is simulated to validate the proposed model for system-and circuit-level designs. The simulation results demonstrate that the proposed model opens the possibility to explore STO technology in a wide range of applications.
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| 17. |
- Chen, Tingsu, et al.
(författare)
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Integration of GMR-based spin torque oscillators and CMOS circuitry
- 2015
-
Ingår i: Solid-State Electronics. - : Elsevier BV. - 0038-1101 .- 1879-2405. ; 111, s. 91-99
-
Tidskriftsartikel (refereegranskat)abstract
- This paper demonstrates the integration of giant magnetoresistance (GMR) spin torque oscillators (STO) with dedicated high frequency CMOS circuits. The wire-bonding-based integration approach is employed in this work, since it allows easy implementation, measurement and replacement. A GMR STO is wire-bonded to the dedicated CMOS integrated circuit (IC) mounted on a PCB, forming a (GMR STO + CMOS IC) pair. The GMR STO has a lateral size of 70 nm and more than an octave of tunability in the microwave frequency range. The proposed CMOS IC provides the necessary bias-tee for the GMR STO, as well as electrostatic discharge (ESD) protection and wideband amplification targeting high frequency GMR STO-based applications. It is implemented in a 65 nm CMOS process, offers a measured gain of 12 dB, while consuming only 14.3 mW and taking a total silicon area of 0.329 mm(2). The measurement results show that the (GMR STO + CMOS IC) pair has a wide tunability range from 8 GHz to 16.5 GHz and improves the output power of the GMR STO by about 10 dB. This GMR STO-CMOS integration eliminates wave reflections during the signal transmission and therefore exhibits good potential for developing high frequency GMR STO-based applications, which combine the features of CMOS and STO technologies. (C) 2015 Elsevier Ltd. All rights reserved.
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| 18. |
- Chen, Tingsu, et al.
(författare)
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Wideband Amplifier Design for Magnetic Tunnel JunctionBased Spin Torque Oscillators
- 2012
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Ingår i: Proc. of GigaHertz Symposium 2012.
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Konferensbidrag (refereegranskat)abstract
- Spin torque oscillator (STO) is a novel current-control-oscillator (CCO), based on two spintronic effects: spin momentum transfer torque and magneto-resistance (MR). It features large tunability, miniature size, high integration level, high quality factor, high operation frequency, etc., which makes it a promising technology for microwave and radar applications. However, the STO is still an immature technology, which requires intensive research for improving the spectrum purity and the output power performance [1]. This paper proposes a wideband amplifier targeting magnetic tunnel junction (MTJ) type of STO device, which compensates the low output power of the STO. The MTJ STO devices can cover a large part of ultra-wideband (UWB) from 3 - 8 GHz and provide an output power from -60 dBm to -40 dBm by tuning the bias DC current and the magnetic field [2][3]. One important and potential application of STO device is a local oscillator (LO) in an RF transceiver. To achieve this task, the amplifier requires a gain of 45 - 65 dB. In addition, the source impedance of different MTJ STO devices varies from a dozen to several hundred Ohms, which makes the amplifier design challenging. An universal amplifier, which fulfills the extracted design requirements, is proposed. It is composed of two types of Balun-LNAs depending on the MR of STO devices as the input stages, a broadband limiting amplifier chain and an output buffer. A combination of a common source (CS) stage and a cross-coupled common gate (CG) stage is employed for the input Balun-LNA in the low impedance case while a cascoded CS stage is used in the high impedance case. The output of both LNAs is connected to a limiting amplifier chain, which provides enough voltage gain. An output buffer is used as the output stage to convert the balanced output to single-ended output and to match the output impedance to 50 Ohms. The proposed wideband amplifier for MTJ STO is implemented in a 65nm CMOS process with 1.2 V supply. In the band of interest, it exhibits 55 dB gain with a maximum noise figure (NF) of 4.5 dB in the small MR case, and a 59 dB gain with a maximum NF of 3 dB in the large MR case. Besides the low noise performance and the high gain, the simulation results of the proposed amplifier also show that it has low power consumption and moderate impedance matching in the frequency range of 3 - 8 GHz, which is suitable for MTJ STO applications.
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| 19. |
- Dora, Ayadi, et al.
(författare)
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System level design of radio frequency receiver for IEEE 802.16 standard
- 2008
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Ingår i: 3rd International Design and Test Workshop, 2008, IDT 2008. - 9781424434794 ; , s. 82-86
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Konferensbidrag (refereegranskat)abstract
- this paper presents a system level design of radio frequency receiver supporting WiMAX mobile standard. Based on direct conversion receiver, the distribution of the total radio system specifications to the individual receiver components is discussed. System level design techniques and theoretical calculation are developed. Simulation results and system simulation level are introduced for noise figure (NF), gain and linearity (third order intercept point, IIP3). Specifications obtained from the received budget can indicate that the noise and the linearity depend on the gain performance of the corresponding circuit blocks. The receiver achieves a total gain of 23dB and an IIP3 of -7.8dBm for low gain mode. It provides up to 68dB gain, 6.5dB noise figure and -16dBm IIP3 for high gain mode.
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| 20. |
- Falster, Daniel, et al.
(författare)
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AusTraits, a curated plant trait database for the Australian flora
- 2021
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Ingår i: Scientific Data. - : Nature Portfolio. - 2052-4463. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- We introduce the AusTraits database - a compilation of values of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 448 traits across 28,640 taxa from field campaigns, published literature, taxonomic monographs, and individual taxon descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological attributes (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised individual- and species-level measurements coupled to, where available, contextual information on site properties and experimental conditions. This article provides information on version 3.0.2 of AusTraits which contains data for 997,808 trait-by-taxon combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data, which also provides a template for other national or regional initiatives globally to fill persistent gaps in trait knowledge.
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| 21. |
- Fernández Schrunder, Alejandro, 1993-, et al.
(författare)
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A Bioimpedance Spectroscopy Interface for EIM Based on IF-Sampling and Pseudo 2-Path SC Bandpass ΔΣ ADC
- 2024
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Ingår i: IEEE Transactions on Biomedical Circuits and Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1932-4545 .- 1940-9990. ; , s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a low-noise bioimpedance (bio-Z) spectroscopy interface for electrical impedance myography (EIM) over the 1 kHz to 2 MHz frequency range. The proposed interface employs a sinusoidal signal generator based on direct-digital-synthesis (DDS) to improve the accuracy of the bio-Z reading, and a quadrature low-intermediate frequency (IF) readout to achieve a good noise-to-power efficiency and the required data throughput to detect muscle contractions. The readout is able to measure baseline and time-varying bio-Z by employing robust and power-efficient low-gain IAs and sixth-order single-bit bandpass (BP) ΔΣ ADCs. The proposed bio-Z spectroscopy interface is implemented in a 180 nm CMOS process, consumes 344.3 - 479.3 μ W, and occupies 5.4 mm 2 area. Measurement results show 0.7 mΩ/√Hz sensitivity at 15.625 kHz, 105.8 dB SNR within 4 Hz bandwidth, and a 146.5 dB figure-of-merit. Additionally, recording of EIM in time and frequency domain during contractions of the bicep brachii muscle demonstrates the potential of the proposed bio-Z interface for wearable EIM systems.
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| 22. |
- Fernández Schrunder, Alejandro, 1993-, et al.
(författare)
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A Finite Element Analysis and Circuit Modelling Methodology for Studying Electrical Impedance Myography of Human Limbs
- 2022
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9294 .- 1558-2531. ; 69:1, s. 244-255
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Electrical impedance myography (EIM) measures bioimpedance over muscles. This paper proposes a circuit-based modelling methodology originated from finite element analysis (FEA), to emulate tissues and effects from anthropometric variations, and electrode placements, on EIM measurements. The proposed methodology is demonstrated on the upper arms and lower legs. Methods: FEA evaluates impedance spectra (Z-parameters), sensitivity, and volume impedance density for variations of subcutaneous fat thickness (tf), muscle thickness (tm), and inter-electrode distance (IED), on limb models over 1Hz-1MHz frequency range. The limbs models are based on simplified anatomical data and dielectric properties from published sources. Contributions of tissues to the total impedance are computed from impedance sensitivity and density. FEA Z-parameters are imported into a circuit design environment, and used to develop a three Cole dispersion circuit-based model. FEA and circuit model simulation results are compared with measurements on ten human subjects. Results: Muscle contributions are maximized at 31.25kHz and 62.5kHz for the upper arm and lower leg, respectively, at 4cm IED. The circuit model emulates variations in tf and tm, and simulates up to 89 times faster than FEA. The circuit model matches subjects measurements with RMS errors < 36.43 and < 17.28, while FEA does with < 36.59 and < 4.36. Conclusions: We demonstrate that FEA is able to estimate the optimal frequencies and electrode placements, and circuit-based modelling can accurately emulate the limbs bioimpedance. Significance: The proposed methodology facilitates studying the impact of biophysical principles on EIM, enabling the development of future EIM acquisition systems.
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| 23. |
- Fernández Schrunder, Alejandro, 1993-, et al.
(författare)
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A Real-Time Muscle Fatigue Detection System Based on Multi-Frequency EIM and sEMG for Effective NMES
- 2024
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Ingår i: IEEE Sensors Journal. - : Institute of Electrical and Electronics Engineers (IEEE). - 1530-437X .- 1558-1748. ; , s. 1-1
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Tidskriftsartikel (refereegranskat)abstract
- Neuromuscular electrical stimulation (NMES) is a self-directed home based therapeutic tool in early rehabilitation for musculoskeletal (MSK) conditions. However, the effectiveness of traditional NMES is fundamentally constrained by muscle fatigue. To address this limitation, this work proposes a detection system, which simultaneously records multifrequency electrical impedance myography (EIM) and surface electromyography(sEMG) in real time for time-frequency analysis of muscle activation, contraction, and fatigue. To demonstrate the ability to monitor these muscle physiological states, two experiments involving weightless and weighted dynamic contractions of the biceps brachii muscle were performed. Results from these experiments show synchronous changes in sEMG and EIM spectra during contractions, and clear trends in sEMG’s mean power frequency (MPF) and EIM spectra with fatigue progression. Additionally, the configurable 4-channel NMES has been electrically evaluated for clinical use, demonstrating the feasibility of the proposed system for closed-loop stimulation. This work showcases the potential of sEMG and multi-frequency EIM to enhance the effectiveness of NMES for MSK conditions by capturing the behavior of distinct mechanisms of muscle fatigue.
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| 24. |
- Garcia, Julian, et al.
(författare)
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A Low-Power CT Incremental 3rd Order Sigma Delta ADC for Biosensor Applications
- 2013
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Ingår i: IEEE Transactions on Circuits and Systems. Part 1: Regular Papers. - : IEEE Press. - 1549-8328. ; 60:1, s. 25-36
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a 3rd order single-loop continuous-time incremental sigma-delta analogue-to-digital converter (ADC) for time-multiplexed signals. Incremental sigma-delta modulation is used to address medium to high resolution requirements of multi-channel applications, while a 3rd order continuous-time implementation is investigated as an alternative for low-power solutions. A prototype of the proposed modulator, running at 320 kHz, has been fabricated in a 0.15- mCMOStechnology,while the synchronization circuitry to allow incremental operation was built on-board. Measurement results show that the ADC achieves 65.3 dB peak SNR, 64 dB peak SNDR and 68.2 dB dynamic range over a 2 kHz bandwidth. The modulator’s power dissipation is 96 W from a 1.6 V power supply. This translates into the best figure-ofmerit when compared to recently published continuous-time alternatives, while being competitive with respect to state-of-the-art discrete-time counterparts.
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| 25. |
- Garcia, Julian, et al.
(författare)
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On Continuous-Time Incremental Sigma Delta ADCs With Extended Range
- 2013
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 62:1, s. 60-70
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the use of continuous-time implementation in extended-range (ER) incremental sigma-delta analog-to-digital converters is analyzed in order to explore a possible solution to low-power multichannel applications. The operation principle, possible loop filter topologies, and critical issues are considered using a general approach. It is demonstrated that, in order to fully benefit from ER, careful attention has to be paid to the analog-digital transfer function mismatches. A third-order single-bit topology validates the theoretical analysis. Its performance is evaluated while the impact of key circuit nonidealities is quantified through behavioral-level simulations. It is shown that, by applying analog-digital mismatch compensation in the digital domain, it is possible to relax the amplifiers' finite gain-bandwidth product and finite dc gain requirements, thus allowing a power-conscious alternative.
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