Design of an adaptive LNA for hand-held devices in a 1-V 90-nm standard RF CMOS technology: From circuit analysis to layout

[EN]: This paper deals the design of a reconfigurable Low-Noise Amplifier (LNA) for the next generation of wireless hand-held devices by using a lumped circuit approach based on physical laws. The purpose is not only to present simulation results showing the fulfillment of different standard specifications, but also to demonstrate that each design step has a physical meaning such that the mathematical design flow is simple as well as suitable for hand-work in both laboratory and classroom. The circuit under analysis, which is designed according to technological design rules of a 90nm CMOS technology, is a two-stage topology including inductive-source degeneration, MOS-varactor based tuning networks, and programmable bias currents. This proposal, with reduced number of inductors and minimum power dissipation, adapts its performance to different standard specifications; the LNA is designed to cope with the requirements of GSM (PCS1900), WCDMA, Bluetooth and WLAN (IEEE 802.11b-g). In order to evaluate the effect of technology parasitics on the LNA performance, simulation results demonstrate that the LNA features NF16dB, S11-3.3 dBm over the 1.85-2.48 GHz band. For all the standards under study the adaptive power consumption varies from 25.3 mW to 53.3mW at a power supply of 1-V. The layout of the reconfigurable LNA occupies an area of 1.8mm2.[ES]: Este trabajo presenta el diseño de un amplificador de bajo ruido, LNA (del inglés Low‐Noise Amplifier) reconfigurable para la siguiente generación de dispositivos portátiles de comunicación inalámbricos, usando la aproximación de circuitos concentrados sustentada en leyes físicas. El propósito de este trabajo no es sólo presentar resultados de simulación que muestran el cumplimiento de especificaciones para cada estándar, sino también demostrar que cada paso de diseño tiene un significado físico haciendo que el procedimiento matemático de diseño sea simple y adecuado para el trabajo a mano tanto para actividades en laboratorio como en el aula. El circuito bajo análisis, diseñado en una tecnología CMOS 90nm, consta de dos etapas que incluyen degeneración inductiva de fuente, redes de entonado basadas en varactores MOS, y corrientes de polarización programables. Esta propuesta, con reducido número de inductores y mínima disipación de potencia, adapta su desempeño a las diversas especificaciones de cada estándar; el LNA se diseña para cubrir los requerimientos de GSM (PCS1900), WCDMA, Bluetooth y WLAN (IEEE 802.11b‐g). Para evaluar el efecto de las no idealidades de la tecnología en el desempeño del LNA, las simulaciones demuestran que el circuito cumple parámetros como NF16dB, S11< ‐5.5dB, S22‐3.3dBm en la banda 1.85‐ 2.48GHz. Para todos los estándares bajo estudio, el consumo adaptivo de potencia varía de 25.3 mW a 53.3mW usando una fuente de alimentación de 1‐V. El patrón geométrico del LNA reconfigurable consume un área de 1.8mm2.Peer Reviewe

The mineralocorticoid receptor forms higher order oligomers upon DNA binding.

The mineralocorticoid and glucocorticoid receptors (MR and GR) are evolutionary related nuclear receptors with highly conserved DNA- and ligand-binding domains (DBD and LBD), which determine promiscuous activation by corticosteroid hormones (aldosterone and glucocorticoids) and binding to a shared DNA consensus sequence, the hormone response element (HRE). In addition, MR and GR functionally interact, likely through direct formation of heteromeric complexes, potentially contributing to cell-specific corticosteroid signaling. It has recently been proposed that agonist and DNA binding promote GR self-association in tetramers. Here we investigated MR quaternary arrangement after receptor activation. To that end we used a fluorescence imaging technique, Number & Brightness (N&B) analysis, in a cell system where receptor-DNA interaction can be studied in live cells in real time. Our results show that agonist-bound MR is a tetramer in the nucleoplasm, forming higher order oligomers upon binding to HREs. Antagonists form intermediate quaternary arrangements, suggesting that the formation of large oligomeric complexes is essential for function. We also show that divergence between MR and GR quaternary arrangements are driven by different functionality of multimerization interfaces in the DBD and LBD and their interplay with the N-terminal domain. In spite of contrasting quaternary structures, MR and GR are able to form heteromers. Given the importance of both receptors as pharmacological targets and the differential oligomerization induced by antagonists, our findings suggest that influencing quaternary structure may be important to provide selective modulation of corticosteroid signaling

The 2HWC HAWC Observatory Gamma Ray Catalog

We present the first catalog of TeV gamma-ray sources realized with the recently completed High Altitude Water Cherenkov Observatory (HAWC). It is the most sensitive wide field-of-view TeV telescope currently in operation, with a 1-year survey sensitivity of ~5-10% of the flux of the Crab Nebula. With an instantaneous field of view >1.5 sr and >90% duty cycle, it continuously surveys and monitors the sky for gamma ray energies between hundreds GeV and tens of TeV. HAWC is located in Mexico at a latitude of 19 degree North and was completed in March 2015. Here, we present the 2HWC catalog, which is the result of the first source search realized with the complete HAWC detector. Realized with 507 days of data and represents the most sensitive TeV survey to date for such a large fraction of the sky. A total of 39 sources were detected, with an expected contamination of 0.5 due to background fluctuation. Out of these sources, 16 are more than one degree away from any previously reported TeV source. The source list, including the position measurement, spectrum measurement, and uncertainties, is reported. Seven of the detected sources may be associated with pulsar wind nebulae, two with supernova remnants, two with blazars, and the remaining 23 have no firm identification yet.Comment: Submitted 2017/02/09 to the Astrophysical Journa

Constraining the pˉ/p\bar{p}/p Ratio in TeV Cosmic Rays with Observations of the Moon Shadow by HAWC

An indirect measurement of the antiproton flux in cosmic rays is possible as the particles undergo deflection by the geomagnetic field. This effect can be measured by studying the deficit in the flux, or shadow, created by the Moon as it absorbs cosmic rays that are headed towards the Earth. The shadow is displaced from the actual position of the Moon due to geomagnetic deflection, which is a function of the energy and charge of the cosmic rays. The displacement provides a natural tool for momentum/charge discrimination that can be used to study the composition of cosmic rays. Using 33 months of data comprising more than 80 billion cosmic rays measured by the High Altitude Water Cherenkov (HAWC) observatory, we have analyzed the Moon shadow to search for TeV antiprotons in cosmic rays. We present our first upper limits on the $\bar{p}/p$ fraction, which in the absence of any direct measurements, provide the tightest available constraints of $\sim1\%$ on the antiproton fraction for energies between 1 and 10 TeV.Comment: 10 pages, 5 figures. Accepted by Physical Review

The Sensitivity of HAWC to High-Mass Dark Matter Annihilations

The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in central Mexico at 19 degrees North latitude and 4100 m above sea level, HAWC will observe gamma rays and cosmic rays with an array of water Cherenkov detectors. The full HAWC array is scheduled to be operational in Spring 2015. In this paper, we study the HAWC sensitivity to the gamma-ray signatures of high-mass (multi- TeV) dark matter annihilation. The HAWC observatory will be sensitive to diverse searches for dark matter annihilation, including annihilation from extended dark matter sources, the diffuse gamma-ray emission from dark matter annihilation, and gamma-ray emission from non-luminous dark matter subhalos. Here we consider the HAWC sensitivity to a subset of these sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the Galactic center. We simulate the HAWC response to gamma rays from these sources in several well-motivated dark matter annihilation channels. If no gamma-ray excess is observed, we show the limits HAWC can place on the dark matter cross-section from these sources. In particular, in the case of dark matter annihilation into gauge bosons, HAWC will be able to detect a narrow range of dark matter masses to cross-sections below thermal. HAWC should also be sensitive to non-thermal cross-sections for masses up to nearly 1000 TeV. The constraints placed by HAWC on the dark matter cross-section from known sources should be competitive with current limits in the mass range where HAWC has similar sensitivity. HAWC can additionally explore higher dark matter masses than are currently constrained.Comment: 15 pages, 4 figures, version to be published in PR

Observation of the Crab Nebula with the HAWC Gamma-Ray Observatory

The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been used for the past 25 years as a reference source in TeV astronomy, for calibration and verification of new TeV instruments. The High Altitude Water Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe the Crab Nebula at high significance across nearly the full spectrum of energies to which HAWC is sensitive. HAWC is unique for its wide field-of-view, nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's sensitivity improves with the gamma-ray energy. Above $\sim$1 TeV the sensitivity is driven by the best background rejection and angular resolution ever achieved for a wide-field ground array. We present a time-integrated analysis of the Crab using 507 live days of HAWC data from 2014 November to 2016 June. The spectrum of the Crab is fit to a function of the form $\phi(E) = \phi_0 (E/E_{0})^{-\alpha -\beta\cdot{\rm{ln}}(E/E_{0})}$. The data is well-fit with values of $\alpha=2.63\pm0.03$, $\beta=0.15\pm0.03$, and log$_{10}(\phi_0~{\rm{cm}^2}~{\rm{s}}~{\rm{TeV}})=-12.60\pm0.02$ when $E_{0}$ is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the systematic errors in this HAWC measurement is discussed and estimated to be $\pm$50\% in the photon flux between 1 and 37 TeV. Confirmation of the Crab flux serves to establish the HAWC instrument's sensitivity for surveys of the sky. The HAWC survey will exceed sensitivity of current-generation observatories and open a new view of 2/3 of the sky above 10 TeV.Comment: Submitted 2017/01/06 to the Astrophysical Journa