2,931 research outputs found
5 Watt GaN HEMT Power Amplifier for LTE
This work presents the design and implementation of a stand-alone linear power amplifier at 2.4 GHz with high output power. A GaN HEMT transistor is selected for the design and implementation of the power amplifier. The device exhibits a gain of 11.7 dB and a drain efficiency of 39% for an output power of 36.7 dBm at 2.4 GHz for an input power of 25dBm. The carrier to intermodulation ratio is better than 25 dB for a two tone input signal of 25 dBm of total power and a spacing of 5 MHz. The fabricated device is also tested with LTE input signals of different bandwidths (5MHz to 20MHz)
Impurities and electronic localization in graphene bilayers
We analyze the electronic properties of bilayer graphene with Bernal stacking
and a low concentration of adatoms. Assuming that the host bilayer lies on top
of a substrate, we consider the case where impurities are adsorbed only on the
upper layer. We describe non-magnetic impurities as a single orbital hybridized
with carbon's pz states. The effect of impurity doping on the local density of
states with and without a gated electric field perpendicular to the layers is
analyzed. We look for Anderson localization in the different regimes and
estimate the localization length. In the biased system, the field induced gap
is partially filled by strongly localized impurity states. Interestingly, the
structure, distribution and localization length of these states depend on the
field polarization.Comment: 7 pages, 6 figure
Filtenna Integration Achieving Ideal Chebyshev Return Losses
This paper demonstrates that it is possible to find an ideal filter response (Chebyshew, Butterworth,..) considering the antenna as the last resonator of a filter under certain circumstances related with the antenna performance and the bandwidth of the filtenna device. If these circumstances are not accomplished, we can achieve excellent performance as well, by means of an iterative process the goal of which is defined by either a filter mask or a classical filter function itself. The methodology is based on the conventional coupling matrix technique for filter design and has been validated by fabricating a microstrip prototype using hairpin resonators and a rectangular patch antenna
Nonlinear Performance of BAW Filters Including BST Capacitors
This paper evaluates the nonlinear effects occurring in a bulk acoustic wave (BAW) filter which includes barium strontium titanate (BST) capacitors to cancel the electrostatic capacitance of the BAW resonators. To do that we consider the nonlinear effects on the BAW resonators by use of a nonlinear Mason model. This model accounts for the distributed nonlinearities inherent in the materials forming the resonator. The whole filter is then implemented by properly connecting the resonators in a balanced configuration. Additional BST capacitors are included in the filter topology. The nonlinear behavior of the BST capacitors is also accounted in the overall nonlinear assessment. The whole circuit is then used to evaluate its nonlinear behavior. It is found that the nonlinear contribution arising from the ferroelectric nature of the BST capacitors makes it impractical to fulfill the linearity requirements of commercial filters
The influence of indol butyric-acid in Prunus laurocerasus L. vegetative propagation
Cherry laurel is very common as an ornamental plant, due to the large glossy
leaves, fast growth, and shade and hedging tolerance. The influence of different indol-3-
butiric acid (IBA) concentrations (1,000, 2,500, 5,000 and 7,500 ppm) was evaluated in
early spring 2007. The data was gathered one month after bench cutting plantation. The
parameters measured and analyzed were the number of rooted cuttings, the number of
cuttings with callus formation and mortality, the mean number of roots (NR) and the
mean main root length (MRL), per rooted cutting. The IBA application influenced the
rooting percentage, the NR and the MRL, but the results were IBA concentration
independent. In P. laurocerasus rooting ranged from 67% and 80%, when IBA was
applied, values significantly superior to 37% of rooted cuttings in the control. The
highest NR and MRL values were found in the treatment with 7,500 ppm IBA (27.2 of
roots per cutting) and with 1,000 ppm IBA (MRL was 24.76 mm), respectively.
Significantly lower values were obtained in the control: 5.56 NR and 9.4 mm of MRL.
The IBA application significantly increased rooting, the NR and the MRL, with cuttings
planted early in Spring, but the parameters were IBA concentration independent
High-precision analysis of binary stars with planets. I. Searching for condensation temperature trends in the HD 106515 system
We explore the probable chemical signature of planet formation in the
remarkable binary system HD 106515. The A star hosts a massive long-period
planet with 9 MJup detected by radial velocity. We also refine stellar and
planetary parameters by using non-solar-scaled opacities when modeling the
stars. Methods. We carried out a simultaneous determination of stellar
parameters and abundances, by applying for the first time non-solar-scaled
opacities in this binary system, in order to reach the highest possible
precision. Results. The stars A and B in the binary system HD 106515 do not
seem to be depleted in refractory elements, which is different when comparing
the Sun with solar-twins. Then, the terrestrial planet formation would have
been less efficient in the stars of this binary system. Together with HD
80606/7, this is the second binary system which does not seem to present a
(terrestrial) signature of planet formation, and hosting both systems an
eccentric giant planet. This is in agreement with numerical simulations, where
the early dynamical evolution of eccentric giant planets clear out most of the
possible terrestrial planets in the inner zone. We refined the stellar mass,
radius and age for both stars and found a notable difference of 78% in R
compared to previous works. We also refined the planet mass to mp sini = 9.08
+/- 0.20 MJup, which differs by 6% compared with literature. In addition, we
showed that the non-solar-scaled solution is not compatible with the classical
solar-scaled method, and some abundance differences are comparable to NLTE or
GCE effects specially when using the Sun as reference. Then, we encourage the
use of non-solar-scaled opacities in high-precision studies such as the
detection of Tc trends.[abridged]Comment: 9 pages, 10 figures, A&A accepted. arXiv admin note: text overlap
with arXiv:1507.0812
Intergenerational linkages in consumption patterns and the geographical distribution of surnames
We specially thank Luis Ubeda for his very useful suggestions and comments. We
also thank Klaus Desmet, Jaime Kahhat, Javier Ruiz-Castillo, Christian Schultz and two
anonymous refereesThis paper attempts to detect the existence of links in consumption patterns between generations. Preferences
over consumption goods may be determined by the preferences of parents and/or by preferences arising from
the environment. We propose an indirect methodology to overcome the lack of data on consumption choices
of dynasties, i.e., parents and their adult offspring. This new approach is based on the analysis of the correlation
between the geographical distributions of surnames and consumption choices.We show that there is no signifi
cant intergenerational link on consumption patterns for non food goods. Our results also suggest that there is a link
between parents' and children's preferences over food itemsAuthors gratefully acknowledge financial support from
the Spanish MEC through grants ECO2008-05721, ECO2011-29751, ECO 2010-19596
and ECO2010-19830. Romeu also acknowledges financial support from Fundación SENECA
11998Publicad
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