35,435 research outputs found
Regression modeling for digital test of ΣΔ modulators
The cost of Analogue and Mixed-Signal circuit
testing is an important bottleneck in the industry, due to timeconsuming
verification of specifications that require state-ofthe-
art Automatic Test Equipment. In this paper, we apply
the concept of Alternate Test to achieve digital testing of
converters. By training an ensemble of regression models that
maps simple digital defect-oriented signatures onto Signal to
Noise and Distortion Ratio (SNDR), an average error of 1:7%
is achieved. Beyond the inference of functional metrics, we show
that the approach can provide interesting diagnosis information.Ministerio de Educación y Ciencia TEC2007-68072/MICJunta de Andalucía TIC 5386, CT 30
Programmable low-voltage continuous-time filter for audio applications
The implementation of a continuous-time filter (CTF) useful for audio frequency applications is presented in this paper. The filter functions can be programmed and tuned with two independent control variables. The filter here proposed has been designed to work at 1.5 V of power supply and at a maximum of 0.5 /spl mu/A/OTA for the worst case current consumption. Electrical simulations of a Tow-Thomas biquad (TTB) show the possibility of obtaining low-pass and band-pass filter functions over the 10 Hz-40 kHz frequency range by changing a control current over four decades.Comisión Interministerial de Ciencia y Tecnología TIC-97-064
Design of a CMOS closed-loop system with applications to bio-impedance measurements
This paper proposes a method for impedance measurements based on a closed-loop implementation of CMOS circuits. The proposed system has been conceived for alternate current excited systems, performing simultaneously driving and measuring functions, thanks to feedback. The system delivers magnitude and phase signals independently, which can be optimized separately, and can be applied to any kind of load (resistive and capacitive). Design specifications for CMOS circuit blocks and trade-offs for system accuracy and loop stability have been derived. Electrical simulation results obtained for several loads agree with the theory, enabling the proposed method to any impedance measurement problem, in special, to bio-setups including electrodes.Ministerio de Ciencia e Innovación TEC2007-6807
Doppler tomography of Cataclysmic Variables
The study of cataclysmic variables (CVs), and in particular of the evolution
of their accretion discs throughout their different brightness states, has
benefited largely from the use of indirect imaging techniques. I report on the
latest results obtained from Doppler tomography of CVs concentrating mainly on
results published since the 2000 Astrotomography meeting in Brussels. Emphasis
is given to the spiral structures found in the accretion discs of some CVs, to
the evolution of these structures throughout quiescence and outburst, and to
our search for them in more systems.Comment: 4 pages, 1 figure. Accepted for publication in AN. Proceedings of the
Astrotomography Joint Discussion 09 of the IAU General Assembly 2003. Uses
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On Essential Incompleteness of Hertz's Experiments on Propagation of Electromagnetic Interactions
The historical background of the 19th century electromagnetic theory is
revisited from the standpoint of the opposition between alternative approaches
in respect to the problem of interactions. The 19th century electrodynamics
became the battle-field of a paramount importance to test existing conceptions
of interactions. Hertz's experiments were designed to bring a solid
experimental evidence in favor of one of them. The modern scientific method
applied to analyze Hertz's experimental approach as well as the analysis of his
laboratory notes, dairy and private letters show that Hertz's
"\textit{crucial}" experiments cannot be considered as conclusive at many
points as it is generally implied. We found that alternative Helmholtz's
electrodynamics did not contradict any of Hertz's experimental observations of
transverse components as Maxwell's theory predicted. Moreover, as we now know
from recently published Hertz's dairy and private notes, his first experimental
results indicated clearly on infinite rate of propagation. Nevertheless,
Hertz's experiments provided no further explicit information on non-local
longitudinal components which were such an essential feature of Helmholtz's
theory. Necessary and sufficient conditions for a decisive choice on the
adequate account of electromagnetic interactions are discussed from the
position of modern scientific method
A perturbed differential resultant based implicitization algorithm for linear DPPEs
Let \bbK be an ordinary differential field with derivation . Let
\cP be a system of linear differential polynomial parametric equations in
differential parameters with implicit ideal \id. Given a nonzero linear
differential polynomial in \id we give necessary and sufficient
conditions on for \cP to be dimensional. We prove the existence of
a linear perturbation \cP_{\phi} of \cP so that the linear complete
differential resultant \dcres_{\phi} associated to \cP_{\phi} is nonzero. A
nonzero linear differential polynomial in \id is obtained from the lowest
degree term of \dcres_{\phi} and used to provide an implicitization algorithm
for \cP
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