6,986 research outputs found

    Pulsed digital oscillators

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    The objective of this paper is to collect the main latest results on pulsed digital oscillators. Rigorous and experimental results are presented that show what kind of sequences are at their output, the relation between these sequences and those of first-order sigma-delta modulators and how is their performance in practical applications. A new variation of the standard topology of PDOs, on which the feedback variable is not position but the velocity of the resonator, is also presented. The first preliminary results obtained with a PDO working with a MEMS cantilever for chemical sensing are presented, which show that it is possible to infer the oscillation frequency directly from the bitstream at the output of the oscillator. Finally, the dependence of the oscillation frequency as a function of the initial conditions of the resonator are also analyzed with simulations.Peer ReviewedPostprint (published version

    A CubeSAT payload for in-situ monitoring of pentacene degradation due to atomic oxygen etching in LEO

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    This paper reports and discusses the design and ground tests of a CubeSat payload which allows to measure, in-situ and in real time, the degradation of a polymer of electronic interest due to atomic oxygen etching in LEO. It provides real-time information on how the degradation occurs, eliminating the need to work with samples recovered once the mission has finished. The polymer, TIPS-Pentacene, is deposited on the surface of a microelectromechanical (MEMS) cantilever, which works as a resonator embedded in a Pulsed Digital Oscillator circuit. The mass losses in the polymer due to atomic oxygen corrosion produce variations in the resonant frequency of the MEMS, which is continuously sensed by the circuit and transmitted to the ground. This way, polymer mass losses around 10-12 kg can be detected during the mission. The payload is a part of the 3Cat-1 mission, a nano-satellite aimed at carrying out several scientific experiments.Peer ReviewedPostprint (author's final draft

    Rise time of pulsed parametric oscillators

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    General relations are derived that describe the rise time of the output power of parametric oscillators driven by a time-dependent pump. Both singly resonant and doubly resonant oscillators are discussed. Results of computer calculations using a Gaussian time envelope for the pump pulse are presented and, in the case of the doubly resonant oscillator, are compared to predictions of a steady-state analysis. Agreement between calculated rise times and published values is good

    Influence of the Feedback Filter on the Response of the Pulsed Digital Oscillator

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    This paper introduces a new feedback topology for the Pulsed Digital Oscillator (PDO) and compares it to the classical topology. The `classic' or single feedback topology, introduced in previous works, shows a strong behavior dependence on the damping losses in the MEMS resonator. A new double feedback topology is introduced here in order to help solving this problem. Comparative discrete-time simulations and preliminary experimental measurements have been carried out for both topologies, showing how the new double feedback topology may increase PDO performance for some frequency ranges.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

    A novel method for fatigue testing of MEMS devices containing movable elements

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    In this paper we present an electronic circuit for position or capacitance estimation of MEMS electrostatic actuators based on a switched capacitor technique. The circuit uses a capacitive divider configuration composed by a fixed capacitor and the variable capacitance of the electrostatic actuator for generating a signal that is a function of the input voltage and capacitive ratio. The proposed circuit can be used to actuate and to sense position of an electrostatic MEMS actuator without extra sensing elements. This approach is compatible with the requirements of most analog feedback systems and the circuit topology of pulsed digital oscillators (PDO).Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/EDA-Publishing

    Mathematical models and GNSS interference

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    Time domain Einstein-Podolsky-Rosen correlation

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    We experimentally demonstrate creation and characterization of Einstein-Podolsky-Rosen (EPR) correlation between optical beams in the time domain. The correlated beams are created with two independent continuous-wave optical parametric oscillators and a half beam splitter. We define temporal modes using a square temporal filter with duration TT and make time-resolved measurement on the generated state. We observe the correlations between the relevant conjugate variables in time domain which correspond to the EPR correlation. Our scheme is extendable to continuous variable quantum teleportation of a non-Gaussian state defined in the time domain such as a Schr\"odinger cat-like state.Comment: 4 pages, 4 figure

    Simple, high-performance type II β-BaB2O4 optical parametric oscillator

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    A visible /near-IR optical parametric oscillator (OPO) based on type II phase matching in β-BaB2O4 (BBO) is described. Pumped at 355 nm, this OPO covers 410-2500 nm completely with a single set of standard Nd:YAG cavity optics. The output efficiency is >25 %, the linewidth of the OPO is narrower than 1 -2 cm^-1 without the use of gratings or etalons, and the signal-beam divergence is <400 µrad. Three type I BBO doubling crystals are used to extend the tuning range from 208 to 415 nm. Doubling efficiencies as high as 40% are easily obtained. The reasons for the high doubling and overall system efficiency are discussed

    Delayed Dynamical Systems: Networks, Chimeras and Reservoir Computing

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    We present a systematic approach to reveal the correspondence between time delay dynamics and networks of coupled oscillators. After early demonstrations of the usefulness of spatio-temporal representations of time-delay system dynamics, extensive research on optoelectronic feedback loops has revealed their immense potential for realizing complex system dynamics such as chimeras in rings of coupled oscillators and applications to reservoir computing. Delayed dynamical systems have been enriched in recent years through the application of digital signal processing techniques. Very recently, we have showed that one can significantly extend the capabilities and implement networks with arbitrary topologies through the use of field programmable gate arrays (FPGAs). This architecture allows the design of appropriate filters and multiple time delays which greatly extend the possibilities for exploring synchronization patterns in arbitrary topological networks. This has enabled us to explore complex dynamics on networks with nodes that can be perfectly identical, introduce parameter heterogeneities and multiple time delays, as well as change network topologies to control the formation and evolution of patterns of synchrony

    Dynamical two-mode squeezing of thermal fluctuations in a cavity opto-mechanical system

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    We report the experimental observation of two-mode squeezing in the oscillation quadratures of a thermal micro-oscillator. This effect is obtained by parametric modulation of the optical spring in a cavity opto-mechanical system. In addition to stationary variance measurements, we describe the dynamic behavior in the regime of pulsed parametric excitation, showing enhanced squeezing effect surpassing the stationary 3dB limit. While the present experiment is in the classical regime, our technique can be exploited to produce entangled, macroscopic quantum opto-mechanical modes
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