A new method for the determination of the locking range of oscillators

A time-domain method for the determination of the injection-locking range of oscillators is presented. The method involves three time dimensions: the first and the second are warped time scales used for the free-running frequency and the external excitation, respectively and the third is to account for slow transients to reach a steady-state regime. The locking range is determined by tuning the frequency of the external excitation until the oscillator locks. The locking condition is determined by analyzing the Jacobian matrix of the system. The method is advantageous in that the computational effort is independent of the presence of widely separated time constants in the oscillator. Numerical results for a Van Der Pol oscillator are presented

Large-signal device simulation in time- and frequency-domain: a comparison

The aim of this paper is to compare the most common time- and frequency-domain numerical techniques for the determination of the steady-state solution in the physics-based simulation of a semiconductor device driven by a time-periodic generator. The shooting and harmonic balance (HB) techniques are applied to the solution of the discretized drift-diffusion device model coupled to the external circuit embedding the semiconductor device, thus providing a fully nonlinear mixed mode simulation. The comparison highlights the strong and weak points of the two approaches, basically showing that the time-domain solution is more robust with respect to the initial condition, while the HB solution provides a more rapid convergence once the initial datum is close enough to the solution itsel

Power waves formulation of oscillation conditions: avoidance of bifurcation modes in cross-coupled VCO architectures

This paper discusses necessity of power-waves formulation to extend voltage-current oriented approaches based on linear concepts such as admittance/impedance operators and transfer-function representations. Importance of multi-physics methodologies, throughout power-waves formulation, for the analysis and design of crystal oscillators is discussed. Interpretation of bifurcation modes in differential cross-coupled VCO architectures in terms of gyrator-like behavior, is proposed. Impact of amplitude level control (ALC) on large-signal phase noise performances is underlined showing necessity of robust control analysis approach relative to power-energy considerations

Determining DfT Hardware by VHDL-AMS Fault Simulation for Biological Micro-Electronic Fluidic Arrays

The interest of microelectronic fluidic arrays for biomedical applications, like DNA determination, is rapidly increasing. In order to evaluate these systems in terms of required Design-for-Test structures, fault simulations in both fluidic and electronic domains are necessary. VHDL-AMS can be used successfully in this case. This paper shows a highly testable architecture of a DNA Bio-Sensing array, its basic sensing concept, fluidic modeling and sensitivity analysis. The overall VHDL-AMS fault simulation of the system is shown

Impact of environmental inputs on reverse-engineering approach to network structures

Background: Uncovering complex network structures from a biological system is one of the main topic in system biology. The network structures can be inferred by the dynamical Bayesian network or Granger causality, but neither techniques have seriously taken into account the impact of environmental inputs. Results: With considerations of natural rhythmic dynamics of biological data, we propose a system biology approach to reveal the impact of environmental inputs on network structures. We first represent the environmental inputs by a harmonic oscillator and combine them with Granger causality to identify environmental inputs and then uncover the causal network structures. We also generalize it to multiple harmonic oscillators to represent various exogenous influences. This system approach is extensively tested with toy models and successfully applied to a real biological network of microarray data of the flowering genes of the model plant Arabidopsis Thaliana. The aim is to identify those genes that are directly affected by the presence of the sunlight and uncover the interactive network structures associating with flowering metabolism. Conclusion: We demonstrate that environmental inputs are crucial for correctly inferring network structures. Harmonic causal method is proved to be a powerful technique to detect environment inputs and uncover network structures, especially when the biological data exhibit periodic oscillations

Optimized auxiliary oscillators for the simulation of general open quantum systems

A method for the systematic construction of few-body damped harmonic oscillator networks accurately reproducing the effect of general bosonic environments in open quantum systems is presented. Under the sole assumptions of a Gaussian environment and regardless of the system coupled to it, an algorithm to determine the parameters of an equivalent set of interacting damped oscillators obeying a Markovian quantum master equation is introduced. By choosing a suitable coupling to the system and minimizing an appropriate distance between the two-time correlation function of this effective bath and that of the target environment, the error induced in the reduced dynamics of the system is brought under rigorous control. The interactions among the effective modes provide remarkable flexibility in replicating non-Markovian effects on the system even with a small number of oscillators, and the resulting Lindblad equation may therefore be integrated at a very reasonable computational cost using standard methods for Markovian problems, even in strongly non-perturbative coupling regimes and at arbitrary temperatures including zero. We apply the method to an exactly solvable problem in order to demonstrate its accuracy, and present a study based on current research in the context of coherent transport in biological aggregates as a more realistic example of its use; performance and versatility are highlighted, and theoretical and numerical advantages over existing methods, as well as possible future improvements, are discussed.Comment: 23 + 9 pages, 11 + 2 figures. No changes from previous version except publication info and updated author affiliation