Analysis of stability and bifurcations of limit cycles in Chua's circuit through the harmonic balance approach

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS: PART

Novel TCAD oriented definition of the off-state breakdown voltage in Schottky-gate FETs: a 4H SiC MESFET case study

Physics-based breakdown voltage optimization in Schottky-barrier power RF and microwave field-effect transistors as well as in high-speed power-switching diodes is today an important topic in technology computer-aided design (TCAD). OFF-state breakdown threshold criteria based on the magnitude of the Schottky-barrier leakage current can be directly applied to TCAD; however, the results obtained are not accurate due to the large uncertainty in the Schottky-barrier parameters and models arising above all in advanced wide-gap semiconductors and to the need of performing high-temperature simulations to improve the numerical convergence of the model. In this paper, we suggest a novel OFF-state breakdown criterion, based on monitoring the magnitude (at the drain edge of the gate) of the electric field component parallel to the current density. The new condition is shown to be consistent with more conventional definitions and to exhibit a significantly reduced sensitivity with respect to physical parameter variation

Modelli di rumore di dispositivi elettronici a semiconduttore

Questo lavoro è suddiviso sostanzialmente in due parti: nella prima vengono ricavate le espressioni dello spettro delle sorgenti microscopiche di rumore a partire dall'applicazione microscopica della meccanica statistica alle transizioni elementari responsabili delle fluttuazioni stesse, e viene introdotta in modo generale la tecnica di funzione di Green effettuando la connessione con il classico metodo del campo di impedenza introdotto da Shockley (Cap. 2). Nella seconda parte, si prende in considerazione il caso di un generico dispositivo a semiconduttore e si sviluppa una tecnica numerica in grado di valutare in modo efficiente la funzione di Green nel caso di un componente elettronico che lavori in condizione di regime stazionario e che sia descritto da un modello a equazioni differenziali a derivate parziali. Tale metodo numerico è stato implementato, per il caso del modello di trasporto drift-diffusion, nell'ambito del simulatore "general purpose" PADRE degli AT&T Bell Laboratories di Murray Hill, New Jersey, che è in grado di analizzare le caratteristiche elettriche di un generico dispositivo a omo- e eterostruttura avente un numero di contatti arbitrario (Cap. 3). Il Cap. 4, infine, è dedicato alla presentazione dei risultati ottenuti dalla simulazione delle proprietà di rumore di diversi dispositivi elettronici a semiconduttore, confrontandoli con risultati teorici e con altri modelli

Colored noise in oscillators. Phase-amplitude analysis and a method to avoid the Ito-Stratonovich dilemma

We investigate the effect of time-correlated noise on the phase fluctuations of nonlinear oscillators. The analysis is based on a methodology that transforms a system subject to colored noise, modeled as an Ornstein-Uhlenbeck process, into an equivalent system subject to white Gaussian noise. A description in terms of phase and amplitude deviation is given for the transformed system. Using stochastic averaging technique, the equations are reduced to a phase model that can be analyzed to characterize phase noise. We find that phase noise is a drift-diffusion process, with a noise-induced frequency shift related to the variance and to the correlation time of colored noise. The proposed approach improves the accuracy of previous phase reduced models

Compact conversion and cyclostationary noise modelling of pn junction diodes in low-injection - Part I: Model derivation

Starting from the well known low-injection approximation, a closed form, analytical compact model is derived for the small-signal (SS) and forced quasi-periodic operation of junction diodes. The model determines the small-signal and conversion admittance matrix of the device as a function of the applied (dc or periodic-time varying) bias. Noise characteristics, in both the stationary (SS) and cyclostationary cases, are also evaluated by means of a Green's function approach