1,989 research outputs found
Concepts and methods in optimization of integrated LC VCOs
Underlying physical mechanisms controlling the noise properties of oscillators are studied. This treatment shows the importance of inductance selection for oscillator noise optimization. A design strategy centered around an inductance selection scheme is executed using a practical graphical optimization method to optimize phase noise subject to design constraints such as power dissipation, tank amplitude, tuning range, startup condition, and diameters of spiral inductors. The optimization technique is demonstrated through a design example, leading to a 2.4-GHz fully integrated, LC voltage-controlled oscillator (VCO) implemented using 0.35-ÎĽm MOS transistors. The measured phase-noise values are -121, -117, and -115 dBc/Hz at 600-kHz offset from 1.91, 2.03, and 2.60-GHz carriers, respectively. The VCO dissipates 4 mA from a 2.5-V supply voltage. The inversion mode MOSCAP tuning is used to achieve 26% of tuning range. Two figures of merit for performance comparison of various oscillators are introduced and used to compare this work to previously reported results
Information Mechanics
I hypothesize the unification of action and entropy and suggest an
interpretation where this hypothesis is able to reconcile the Bohemian and
Copenhagen interpretations of quantum mechanics. I explore the hypothesis
implications to the discretization of space; both for a particle and for the
vacuum itself. I argue the second law of thermodynamics is the justification
for the principle of least action. Similarities with the spin networks of
quantum loop gravity are found and the exact simplified area of the network is
given. An experiment to test the theory is suggested. I conclude with comments
on the non-local interpretation of nature.Comment: A 16 page report with figures. Originally written in August 199
Hierarchically coupled ultradian oscillators generating robust circadian rhythms
Ensembles of mutually coupled ultradian cellular oscillators have been proposed by a number of authors to explain the generation of circadian rhythms in mammals. Most mathematical models using many coupled oscillators predict that the output period should vary as the square root of the number of participating units, thus being inconsistent with the well-established experimental result that ablation of substantial parts of the suprachiasmatic nuclei (SCN), the main circadian pacemaker in mammals, does not eliminate the overt circadian functions, which show no changes in the phases or periods of the rhythms. From these observations, we have developed a theoretical model that exhibits the robustness of the circadian clock to changes in the number of cells in the SCN, and that is readily adaptable to include the successful features of other known models of circadian regulation, such as the phase response curves and light resetting of the phase
Chapman-Enskog method and synchronization of globally coupled oscillators
The Chapman-Enskog method of kinetic theory is applied to two problems of
synchronization of globally coupled phase oscillators. First, a modified
Kuramoto model is obtained in the limit of small inertia from a more general
model which includes ``inertial'' effects. Second, a modified Chapman-Enskog
method is used to derive the amplitude equation for an O(2) Takens-Bogdanov
bifurcation corresponding to the tricritical point of the Kuramoto model with a
bimodal distribution of oscillator natural frequencies. This latter calculation
shows that the Chapman-Enskog method is a convenient alternative to normal form
calculations.Comment: 7 pages, 2-column Revtex, no figures, minor change
Josephson parametric reflection amplifier with integrated directionality
A directional superconducting parametric amplifier in the GHz frequency range
is designed and analyzed, suitable for low-power read-out of microwave kinetic
inductance detectors employed in astrophysics and when combined with a
nonreciprocal device at its input also for circuit quantum electrodynamics
(cQED). It consists of an one wavelength long nondegenerate Josephson
parametric reflection amplifier circuit. The device has two Josephson junction
oscillators, connected via a tailored impedance to an on-chip passive circuit
which directs the in- to the output port. The amplifier provides a gain of 20
dB over a bandwidth of 220 MHz on the signal as well as on the idler portion of
the amplified input and the total photon shot noise referred to the input
corresponds to maximally 1.3 photons per second per Hertz of bandwidth. We
predict a factor of four increase in dynamic range compared to conventional
Josephson parametric amplifiers.Comment: Main article (5 pages plus 2 pages references) plus supplemental
material (14 pages
Semi-classical generalized Langevin equation for equilibrium and nonequilibrium molecular dynamics simulation
Molecular dynamics (MD) simulation based on Langevin equation has been widely
used in the study of structural, thermal properties of matters in difference
phases. Normally, the atomic dynamics are described by classical equations of
motion and the effect of the environment is taken into account through the
fluctuating and frictional forces. Generally, the nuclear quantum effects and
their coupling to other degrees of freedom are difficult to include in an
efficient way. This could be a serious limitation on its application to the
study of dynamical properties of materials made from light elements, in the
presence of external driving electrical or thermal fields. One example of such
system is single molecular dynamics on metal surface, an important system that
has received intense study in surface science. In this review, we summarize
recent effort in extending the Langevin MD to include nuclear quantum effect
and their coupling to flowing electrical current. We discuss its applications
in the study of adsorbate dynamics on metal surface, current-induced dynamics
in molecular junctions, and quantum thermal transport between different
reservoirs.Comment: 23 pages, 16 figur
Design of a 41.14-48.11 GHz triple frequency based VCO
© 2019 by the authors. Licensee MDPI, Basel, Switzerland. Growing deployment of more efficient communication systems serving electric power grids highlights the importance of designing more advanced intelligent electronic devices and communication-enabled measurement units. In this context, phasor measurement units (PMUs) are being widely deployed in power systems. A common block in almost all PMUs is a phase locked oscillator which uses a voltage controlled oscillator (VCO). In this paper, a triple frequency based voltage controlled oscillator is presented with low phase noise and robust start-up. The VCO consists of a detector, a comparator, and triple frequency. A VCO starts-up in class AB, then steadies oscillation in class C with low current oscillation. The frequency of the VCO, which is from 13.17 GHz to 16.03 GHz, shows that the frequency is tripling to 41.14-48.11 GHz. Therefore, its application is not limited to PMUs. This work has been simulated in a standard 0.18 µm CMOS process. The simulated VCO achieves a phase noise of -99.47 dBc/Hz at 1 MHz offset and -121.8 dBc/Hz at 10 MHz offset from the 48.11 GHz carrier
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