Characterization of CMOS Spiral Inductors

In this work "full-wave" simulations of integrated inductors are presented and compared with measurements of fabricated CMOS chips. The good agreement between measurements and simulations demonstrates the accuracy of the tool, which is, hence, a cheaper alternative to experimental characterization. Furthermore, the proposed approach may give precious hints for performance improvements, by making internal device fields and currents available for the VLSI designer and providing compact, most effective, equivalent models

Characterisation of dielectric 3D-printing materials at microwave frequencies

3D-printer materials are becoming increasingly appealing, especially for high frequency applications. As such, the electromagnetic characterisation of these materials is an important step in evaluating their applicability for new technological devices. We present a measurement method for complex permittivity evaluation based on a dielectric loaded resonator (DR). Comparing the quality factor Q of the DR with a disk-shaped sample placed on a DR base, with Q obtained when the sample is substituted with an air gap, allows a reliable determination of the loss tangent

A Dielectric Loaded Resonator for the Measurement of the Complex Permittivity of Dielectric Substrates

A new configuration of dielectric-loaded resonator (DR), particularly versatile for the complex permittivity measurement of substrates for microwave circuits, even in the presence of back metal plates, is shown here. To test this technique in a wide interval of the values of the complex permittivity, the versatility of 3-D printing is exploited to print samples with different densities, thus artificially changing the effective permittivity in the interval (1.7-3.1) for the real part and (0.02-0.06) for the imaginary part. The designed resonator, tuned at -12 GHz, is experimentally validated by the comparison of measurements obtained on these samples with a split ring resonator (SRR) and standard transmission/reflection waveguide methods. Then, the versatility of the designed resonator is shown in the characterization of FR4-fiberglass and Kapton polyimide samples

Evolution of mating systems in Euplotes

Ciliates control their sexual phenomenon of conjugation (or mating) through a genetic mechanism of mating types, which may either be only two within a species (recalling the duality of sexes in animals), or multiple (recalling self/non-self compatibility systems in plants and fungi). The nearly one hundred species of the most ubiquitously distributed ciliate, Euplotes, all evolved multiple mating types. Based on analyses of Mendelian genetics, these mating types have for long been assumed to be determined by multi-allelic series of genes inherited at a single genetic locus (i.e., the mating-type or mat locus) and responsible for the synthesis of mating type-pecific signaling proteins. The chemical characterization of these signaling proteins (known as pheromones) from an array of Euplotes species has now permitted us to evolve in the study of Euplotes mating types from an approach of Mendelian genetics to an approach of molecular genetics. In this new experimental context, we have cloned and characterized structurally the pheromone (mating-type) gene families of Euplotes species that take different positions in the phylogenetic tree of the genus Euplotes. It appeared that, in accord with the prediction of the Mendelian genetics, early branching species (e.g., E. polaris, E. raikovi and E. nobilii) inherit their mating types at a single multi-allelic locus. However, in disagreement with the prediction of the Mendelian genetics, late branching species (e.g., E. crassus and E. focardii) inherit their mating types at two distinct loci that are likely the result of an event of gene duplication in the germinal (micronuclear) genome. One locus appears to be structurally and functionally homologous with the multi-allelic locus of the early branching species, while the second locus appears to be structurally homologous but functionally divergent

White matter lesions in watershed territories studied with MRI and parenchymography: a comparative study

Brain aging affects an increasing segment of the population and the role of chronic cerebrovascular disease is considered to be one of the main parameters involved. For this purpose we compared retrospectively MRI data with digitized subtraction angiography (DSA) data in a group of 50 patients focusing onto the watershed area of the carotid artery vascular territories. In order to evaluate the presence of white matter lesions (WML) in the hemispheric watershed areas, coronal fluid-attenuated inversion-recovery or axial T2 weighted MRI images of patients with symptomatic cerebrovascular insufficiency areas were compared with the capillary phase of DSA studies in anterior-posterior projection. Presence of cerebrovascular occlusive disease was evaluated on DSA using North American symptomatic carotid endarterectomy trial criteria and including evaluation of collateral vascular supply. Pathological MRI findings in the region of the watershed territories correlated overall in 66% of cases with a defect or delayed filling on DSA. In the case of asymmetrical MRI findings, there was a pathological finding of the capillary phase in the watershed area in 92% of DSA studies. Hypoperfusion in the capillary phase of the watershed area as seen on DSA correlated with the stenosis degree of the concerned carotid artery. Our findings suggest that asymmetrical findings of WML in the watershed areas as seen on MRI are caused by hemodynamic effect and a differentiation between small vessel disease and a consequence of distant stenosis may be possible under such condition

Low-Noise Ku-Band Receiver Frontend with Switchable SIW Filters for Cubesat Applications

This paper proposes a low-noise receiver frontend for nanosatellite and Cubesat platforms. The frontend is composed by a Low-Noise Amplifier (LNA) and two Substrate Integrated Waveguide (SIW) filters, providing a frequency reconfigurability to the system. The two filters operate in the 13 and in the 14 GHz uplink bands, and are selected by means of a pair of solid-state SPDT switches. As a results, 15.5 dB gain with 2.4 dB noise figure for the 13 GHz configuration and 17.8 dB gain with 2.3 dB noise figure for the 14 GHz configuration are obtained. This work is important since demonstrates a low-cost solution for satellite radio apparatuses based on commercial components on a standard PCB

Low-Noise Block Downconverter based on COTS and SIW Filters for Ku-band Cubesat Transponders

This paper proposes a Low-Noise Block (LNB) downconverter operating in the Ku-band for Cubesat transponders. The frontend is composed by a Low-Noise Amplifier (LNA) and two switchable Substrate Integrated Waveguide (SIW) filters, providing a frequency reconfigurability to the system. The LNB is completed by a downconversion unit, constituted by a mixer, a PLL frequency synthesizer and an IF amplifier. A first breadboard features an overall gain of 54 dB with a 2.3 dB noise figure. The worst case linearity performance indicates an input-referred 1 dB compression point (P1dB) and a third-order intercept point (IIP3) equal to -27 dBm and -16 dBm respectively. This work is important since demonstrates a low-cost solution for satellite radio apparatuses based on commercial components and standard PCB

Microwave investigation of pinning in Te-and cubic-BN-added MgB2

Abstract MgB2 has great potential for many applications, thanks to its relatively high critical temperature and low fabrication cost. Large efforts are done to improve the current carrying capabilities of bulks and tapes in view of different application fields, e.g. with the addition of Te and cubic-BN to MgB2. To elucidate the vortex pinning physics exploiting a different dynamic regime, we present here a microwave study of the pinning properties of spark plasma sintered bulk MgB2 with and without the addition of 0.01 % at. Te or cubic-BN. We show the surface resistance Rs of the MgB2 samples measured with a dielectric-loaded resonator at ~ 16.5 GHz and ~ 26.7 GHz in the 10 K-Tc temperature range at fields up to 1.0 T. Then, the MgB2 Rs is studied with high frequency vortex motion models in order to obtain the pinning constant (Labusch parameter) and the depinning frequency. Finally, the microwave behavior of MgB2 in the mixed state is compared with the recent results obtained on Nb3Sn