31,489 research outputs found
Application of the finite-discrete element method to dynamic stress development in armour units and armour layers
Tunable Balun Low-Noise Amplifier in 65nm CMOS Technology
The presented paper includes the design and implementation of a 65 nm CMOS low-noise amplifier (LNA) based on inductive source degeneration. The amplifier is realized with an active balun enabling a single-ended input which is an important requirement for low-cost system on chip implementations. The LNA has a tunable bandpass characteristics from 4.7 GHz up to 5.6 GHz and a continuously tunable gain from 22 dB down to 0 dB, which enables the required flexibility for multi-standard, multi-band receiver architectures. The gain and band tuning is realized with an optimized tunable active resistor in parallel to a tunable L-C tank amplifier load. The amplifier achieves an IIP3 linearity of -8dBm and a noise figure of 2.7 dB at the highest gain and frequency setting with a low power consumption of 10 mW. The high flexibility of the proposed LNA structure together with the overall good performance makes it well suited for future multi-standard low-cost receiver front-ends
Density Functional Theory Characterization of the Multiferroicity in Spin Spiral Chain Cuprates
The ferroelectricity of the spiral magnets LiCu2O2 and LiCuVO4 was examined
by calculating the electric polarizations of their spin spiral states on the
basis of density functional theory with spin-orbit coupling. Our work
unambiguously reveals that spin-orbit coupling is responsible for the
ferroelectricity with the primary contribution from the spin-orbit coupling on
the Cu sites, but the asymmetric density distribution responsible for the
electric polarization occurs mainly around the O atoms. The electric
polarization is calculated to be much greater for the ab- than for the bc-plane
spin spiral. The observed spin-spiral plane is found to be consistent with the
observed direction of the electric polarization for LiCuVO4, but inconsistent
for LiCu2O2.Comment: Phys. Rev. Lett., in prin
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