Modélisation jusqu'à 45 GHz des couplages entre microvias et cavités en technologie PCB multicouches quelles que soient les frontières

National audienceNous développons ici une modélisation simple du couplage entre les microvias et les cavités créées par les plans métalliques au sein des PCB multicouches. Ce modèle, basé sur la notion d'impédance des plans parallèles permet la prise en compte de frontières des cavités de natures différentes, ouvertes ou réalisées à l'aide de trous métallisés. Le modèle circuit est validé par comparaison avec des simulations électromagnétiques dans la bande 0-45 GHz et cela pour différents cas de figure des frontières de la cavité, en circuit ouvert ou court-circuit réalisé à l'aide de trous perforants métallisés. 1. Introduction Les technologies multicouches telles que le LTCC ou bien encore les PCB multicouches permettent une réduction des dimensions des circuits en utilisant la 3 ième dimension pour réduire les distances. Pour accéder à cette 3 ième dimension il est nécessaire d'utiliser des vias ou des microvias permettant de relier les différentes couches métalliques entre elles. Ces vias et microvias, traversant plusieurs couches métalliques, entraînent des couplages avec les cavités qu'ils traversent ce qui se traduit par des dégradations des signaux[1][2]. Afin de prévoir et de limiter ces effets, il est nécessaire d'avoir une méthode analytique rendant compte rapidement de ces phénomènes de couplage. Nous présentons dans cette communication une méthode basée sur la détermination des modes de cavités [2] tenant compte des frontières des cavités créées par les différents plans métalliques. Ces cavités peuvent être ouvertes ou fermées à l'aide de trous métallisés, les frontières pouvant être de natures différentes suivant le bord de la cavité considéré. L'approche circuit que nous proposons est validée à l'aide de simulations électromagnétiques et de mesures jusqu'à 45 GHz. 2. Modélisation du couplage

Synthèse d'un filtre planaire large bande à base de résonateurs série et parallèle

National audienceCe papier présente la synthèse d'un filtre planaire large bande basé sur une association hybride de résonateurs en série et en parallèle. Les résonateurs en série sont implémentés à l'aide de lignes couplées quart d'onde et les résonateurs en parallèle par des stubs demi-onde en parallèle. Chaque étape de cette synthèse sera détaillée et accompagnée du schéma voire de la réponse électrique associés. Les avantages de cette topologie sont, d'une part, une réduction de l'encombrement vis à vis d'une topologie traditionnelle du même ordre, et d'autre part, l'obtention de zéros de transmission améliorant la réjection de manière notable. Nous prendrons l'exemple de filtres à l'ordre 5 et 11 et une réalisation d'un filtre d'ordre 5 en bande Ku et en technologie microruban sera présentée. Les performances mesurées sont conformes à celles espérées

Multiplexeur hyperfréquence 16 canaux dans la bande 2-18GHz en technologie triplaque

National audienceCe papier présente la conception d'un multiplexeur hyperfréquence planaire découpant le spectre 2-18 GHz en 16 canaux de 1 GHz chacun. La fonction de multiplexage présentée ici est basée sur un découpage singulier de la bande 2-18 Ghz impliquant l'utilisation d'une architecture originale. Celle dernière est constituée d'un diviseur de puissance de type Wilkinson, de deux duplexeurs et de quatre quadriplexeurs. Les performances électriques simulées sont satisfaisantes et le découpage de la bande est opérationnel. Les contraintes d'encombrement ont également été prises en compte dans la conception des circuits. Certains des sous-circuits ont été réalisés en technologie triplaque et valident les résultats simulés

Modelling up to 45 GHz of coupling between microvias and PCB cavities considering several boundary conditions

International audienceModeling up to 45 GHz of coupling between microvias and PCB cavities considering several boundary conditions thierry le gouguec 1 , najib mahdi 1 , ste ' phane cadiou 1 , ce ' dric quendo 1 , erich schlaffer 2 , walter pessl 2 and alain lefevre 3 The recent developments in electronic cards such as the network equipment are characterized by the miniaturization of the board size and the increasing complexity of the layout. Because of these requirements, multi-layered printed circuit boards are commonly used and vias connecting signal lines on different layers, or integrated circuit devices to power and ground planes, are frequently used and often essential. However, a via is not an ideal transmission line. Besides, it creates discontinuities at high frequencies leading to high insertion loss degradation of signal which limits the performances of integrated circuit and systems. In this paper, the impacts of coupling between via and parallel-plates cavity on the response of microwave integrated devices are highlighted in the first part. Then, to describe the intrinsic interaction between the via transition and parallel-plate modes, the notion of parallel-plates matrix impedances is presented and new boundary conditions like open or plated through holes shielded boundaries of the cavities are introduced. Then, using this physics-based model, an intuitive equivalent circuit has been developed. Finally, the proposed approach and the equivalent circuits were validated by using comparisons with electromagnetic simulations and measurements in different scenarios. Three-dimensional (3D) multi-layer technologies such as low temperature co-fired ceramics (LTCC) [1] or high-density multi-layers printed circuit board (HD-PCB) [2] are currently being strongly developed because they offer considerable size reduction as well as the embedded function possibilities. For microwave applications such as filters, couplers, diplexers, etc. [3, 4], these 3D structures offer new design possibilities for frequencies up to 100 GHz. HD-PCB structures consist of several metal layers separated by dielectric substrates. The vias and microvias used in multilayer PCBs allow connecting lines of different metallic levels together or connecting devices to the power and ground plane [5]. The different metal planes can also be connected together with metallic plated through holes (PTHs). With the rise of working frequencies, the stacked multilayer PCB structures are subjected to electromagnetic phenomena like standing waves in cavities or like coupling and interaction between neighboring components. As example of HD-PCB technology, the AT&S TM (PCB manufacturer) technology used during MIDIMU-HD project funded by the Euripides council is presented in Fig. 1. This HD multilayer consists of eight metallic layers (30 mm thickness) separated by Megtron6 (Panasonic TM) sub-strate of 95 mm thickness (depending on the metal densities of each level) and with a relative permittivity 1 r ¼ 3.3 and loss tangent tan(d) ¼ 0.0065 at 40 GHz. A single microvia hole consists of a central cylinder with a diameter of 140 mm, a conductor pad with a diameter of 240 mm, and when this via passes through a metallic plane it will also have a clearance hole called anti-pad of diameter of 350 mm. AT&S is able to stack more than three microvias and to realize buried via with diameter of 200 mm. The PTHs connecting the metal level M1 to the metal level M8 are 200 mm of diameter. Obviously, these multilayer structures which involve parallel planes, dielectric layers, pads, and anti-pads are not ideal transmission components at high frequencies. The electrical behavior of a microvia can be modeled by serial inductance and resistance like is done for a metallic wire [6, 7]. The vias and microvias may cause mismatch [7], crosstalk, reflections, some additional signal delays, and consequently the degradation of signal performance. On the other hand, the coupling between vias, microvias, and parallel plates also plays an important role in the electrical performances of the via transition [8, 9]. The excitation of the parallel plate modes results in conversion of energy between propagation on line and propagation on guided plated structures which imply some transmission zeros

Quadriplexeur hyperfréquence DBR dans la bande 11 -18 GHz

National audienceCet article présente une méthode de conception d'un quadriplexeur hyperfréquence planaire en technologie triplaque utilisé dans la bande 11-18 GHz. Le composant opère un découpage du spectre d'entrée en quatre canaux de largeurs de bande et d'espacements identiques (1 GHz). Le multiplexeur utilise des filtres d'ordre 8 en topologie Dual Behavior Resonator pour assurer un bon niveau de réjection et un contrôle large bande de la réponse. Les quatre canaux sont connectés en parallèle et mutuellement adaptés via un réseau à stub. De plus, de nouveaux modèles électromagnétiques de discontinuités ont été développés, ce qui facilite considérablement la phase de réglage électromagnétique. Un quadriplexeur a été conçu en technologie triplaque qui offre une bonne compacité et isolation entre filtres. Son encombrement est de 17.1 cm² et ses performances simulées sont de 5 dB de pertes d'insertion et des réjections large bande meilleures que 60 dB

Dense gas formation and destruction in a simulated Perseus-like galaxy cluster with spin-driven black hole feedback

Extended filamentary H$\alpha$ emission nebulae are a striking feature of nearby galaxy clusters but the formation mechanism of the filaments, and the processes which shape their morphology remain unclear. We conduct an investigation into the formation, evolution and destruction of dense gas in the center of a simulated, Perseus-like, cluster under the influence of a spin-driven jet. We particularly study the role played by condensation of dense gas from the diffuse intracluster medium, and the impact of direct uplifting of existing dense gas by the jets, in determining the spatial distribution and kinematics of the dense gas. We present a hydrodynamical simulation of an idealised Perseus-like cluster using the adaptive mesh refinement code {\sc ramses}. Our simulation includes a supermassive black hole (SMBH) that self-consistently tracks its spin evolution via its local accretion, and in turn drives a large-scale jet whose direction is based on the black hole's spin evolution. We show that the formation and destruction of dense gas is closely linked to the SMBH's feedback cycle, and that its morphology is highly variable throughout the simulation. While extended filamentary structures readily condense from the hot intra-cluster medium, they are easily shattered into an overly clumpy distribution of gas during their interaction with the jet driven outflows. Condensation occurs predominantly onto infalling gas located 5 - 15 kpc from the center during quiescent phases of the central AGN, when the local ratio of the cooling time to free fall time falls below 20, i.e. when $t_{\rm cool}/t_{\rm ff} < 20$. We find evidence for both condensation and uplifting of dense gas, but caution that purely hydrodynamical simulations struggle to effectively regulate the cluster cooling cycle and produce overly clumpy distributions of dense gas morphologies, compared to observation

Topological insights in polynuclear Ni/Na coordination clusters derived from a schiff base ligand

This article presents the syntheses, crystal structures, topological features and magnetic properties of two NiII/NaI coordination clusters (CCs) formulated [NiII3Na(L1)3(HL1 (MeOH)2] (1) and [NiII6Na(L1)5(CO3)(MeO (MeOH)3(H2O)3]·4(MeOH) 2(H2O) [2 4(MeOH) 2(H2O)] where H2L1 is the semi rigid Schiff base ligand (E)-2-(2-hydroxy-3 methoxybenzylideneamino)-phenol). Compound 1 possesses a rare NiII3NaI cubane (3M4-1) topology and compound 2 is the first example in polynuclear Ni/Na chemistry that exhibits a 2,3,4M7-1 topology

The DAMIC-M experiment: Status and first results

The DAMIC-M (DArk Matter In CCDs at Modane) experiment employs thick, fully depleted silicon charged-coupled devices (CCDs) to search for dark matter particles with a target exposure of 1 kg-year. A novel skipper readout implemented in the CCDs provides single electron resolution through multiple non-destructive measurements of the individual pixel charge, pushing the detection threshold to the eV-scale. DAMIC-M will advance by several orders of magnitude the exploration of the dark matter particle hypothesis, in particular of candidates pertaining to the so-called “hidden sector.” A prototype, the Low Background Chamber (LBC), with 20g of low background Skipper CCDs, has been recently installed at Laboratoire Souterrain de Modane and is currently taking data. We will report the status of the DAMIC-M experiment and first results obtained with LBC commissioning data

Co‐developing guidance for conservation: An example for seabirds in the North‐East Atlantic in the face of climate change impacts

Conservation guidance—an authoritative source of information and recommendations explicitly supporting decision-making and action regarding nature conservation—represents an important tool to communicate evidence-based advice to conservation actors. Given the rapidly increasing pressure that climate change poses to biodiversity, producing accessible, well-informed guidance on how to best manage the impacts and risks of changing climatic conditions is particularly urgent. Guidance documents should ideally be produced with multistage input from stakeholders who are likely to use and implement such advice; however, this step can be complicated and costly, and remains largely unformalized. Moreover, there is currently little direct evidence synthesized for actions that specifically target climate change and guidance remains largely absent. Here, we introduce a process for co-developing guidance for species conservation in the face of climate change, using seabirds in the North-East Atlantic as a case study. Specifically, we collated evidence on climate change vulnerability and possible conservation actions using literature synthesis, stakeholder surveys, and ecological modeling. This evidence base was then discussed, refined, and expanded using structured stakeholder workshops. We summarize the knowledge gained through stakeholder engagement and provide recommendations for future international efforts to co-produce conservation guidance for managing wildlife, in the context of a rapidly changing climate.info:eu-repo/semantics/publishedVersio