147,678 research outputs found
Inverter-Based Low-Voltage CCII- Design and Its Filter Application
This paper presents a negative type second-generation current conveyor (CCII-). It is based on an inverter-based low-voltage error amplifier, and a negative current mirror. The CCII- could be operated in a very low supply voltage such as ±0.5V. The proposed CCII- has wide input voltage range (±0.24V), wide output voltage (±0.24V) and wide output current range (±24mA). The proposed CCII- has no on-chip capacitors, so it can be designed with standard CMOS digital processes. Moreover, the architecture of the proposed circuit without cascoded MOSFET transistors is easily designed and suitable for low-voltage operation. The proposed CCII- has been fabricated in TSMC 0.18μm CMOS processes and it occupies 1189.91 x 1178.43μm2 (include PADs). It can also be validated by low voltage CCII filters
Metallic and semi-metallic <100> silicon nanowires
Silicon nanowires grown along the -direction with a bulk Si core are
studied with density functional calculations. Two surface reconstructions
prevail after exploration of a large fraction of the phase space of nanowire
reconstructions. Despite their energetical equivalence, one of the
reconstructions is found to be strongly metallic while the other one is
semi-metallic. This electronic-structure behavior is dictated by the particular
surface states of each reconstruction. These results imply that doping is not
required in order to obtain good conducting Si nanowires.Comment: 13 pages, 4 figures; Phys. Rev. Lett., in pres
Observational Test of Coronal Magnetic Field Models I. Comparison with Potential Field Model
Recent advances have made it possible to obtain two-dimensional line-of-sight
magnetic field maps of the solar corona from spectropolarimetric observations
of the Fe XIII 1075 nm forbidden coronal emission line. Together with the
linear polarization measurements that map the azimuthal direction of the
coronal magnetic field, these coronal vector magnetograms now allow for direct
observational testing of theoretical coronal magnetic field models. This paper
presents a study testing the validity of potential-field coronal magnetic field
models. We constructed a theoretical coronal magnetic field model of active
region AR 10582 observed by the SOLARC coronagraph in 2004 by a global
potential field extrapolation of the synoptic map of Carrington Rotation 2014.
Synthesized linear and circular polarization maps from thin layers of the
coronal magnetic field model above the active region along the line of sight
are compared with the observed maps. We found that reasonable agreement occurs
from layers located just above the sunspot of AR 10582, near the plane of the
sky. This result provides the first observational evidence that potential field
extrapolation can yield a reasonable approximation of the magnetic field
configuration of the solar corona for simple and stable active regions.Comment: 25 pages, 11 figures. ApJ in pres
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