Paolo Maffezzoni

Analysis of Oscillator Injection Locking Through Phase-Domain Impulse-Response

This paper presents a novel approach to the analysis of oscillator injection locking due to weak external signals. From the intuitive concept of impulse-sensitivity function, a phase-domain macromodel is deduced which is able to capture high-order synchronization effects. Novel closed-form expressions for the synchronization regions are thus presented. The proposed phase-domain macromodel and the expressions derived for synchronization-regions are very general since they apply to any oscillator topology.

An Arnoldi based thermal network reduction method for electro-thermal analysis

In this paper we consider the problem of approximating the large discretized thermal network that models the heat conduction phenomenon in an electrical system by means of models of reduced state-space dimensions. To this aim we present an efficient and numerically stable Arnoldi type algorithm by which a multi-point moment matching approximant of the discretized thermal network is obtained and we apply it to the electro-thermal analysis of an operational transconductance amplifier.

Compact modeling of electrical devices for electrothermal analysis

Discretization of diffusion-equation modeling heat conduction in electrical devices, as needed for accurate electrothermal simulations, tends to produce thermal networks of very large size. This paper investigates an effective method for thermal network complexity reduction preserving high accuracy in electrothermal analysis. The method is based on a suited port-like definition of thermal network and on the use of the truncated balanced-reduction method. The strategy is practically applied to the electrothermal simulation of a power vertical double diffused MOSFET.

Compact thermal networks for modeling packages

In this paper, thermal networks for modeling packages are rigorously introduced. A multipoint moment matching method for state space reduction of these discretized thermal networks is formulated. In this manner reduced thermal networks are derived that can be used as boundary condition independent compact thermal models of packages. This algorithm is successfully applied to the detailed analysis of an idealized ball grid array package.

Synchronization Analysis of Two Weakly Coupled Oscillators Through a PPV Macromodel

This paper adopts a phase-domain macromodel based on perturbation projection vector to study the synchronization effects that take place between two weakly coupled oscillators. Original closed-form expressions for the locking region of the coupled oscillators and for the common locking frequency are derived. The route to synchronization is described analytically by predicting the oscillation frequency shifts, which are induced by mutual pulling as a function of the interaction strength. Under the assumption of a weak coupling, the proposed approach can be applied to a wide class of oscillator topologies.

Evaluating Pulling Effects in Oscillators Due to Small-Signal Injection

This paper presents a hybrid numerical-analytical approach to evaluate and quantify injection pulling effects in RF oscillators. The method employs the Floquet nu1(t) eigenvector to project the perturbation signal into the phase domain. An original closed-form expression for the frequency shift induced by small-signal harmonic perturbations is derived. It is shown that such closed-form expression accurately predicts frequency shift under weak pulling, quasi-lock, as well as locked conditions. An estimation of the main spectrum components of the pulled response is also derived. The proposed macromodeling approach has the peculiarity to be applicable to any oscillator topology.

Measurements and extractions of parasitic capacitances in ULSI layouts

This paper deals with the extraction of parasitic capacitances of interconnects in submicron layouts. It is well known that, in integrated circuits, the signal delay due to interconnects is comparable to that of gates. This aspect becomes particularly important, for example, during the design of clock trees in high-speed applications. In general, capacitance extraction is carried out with software tools but they should be validated on a set of geometrical structures, which have been accurately characterized and that are representative of the circuit layouts. Experimental characterization of these structures and their set up in a golden set of measures is still a challenging task. In this paper, we first describe some experimental approaches to measure capacitances of structures from the golden set and in particular we identify a high accuracy transducer based on pass-gate transistors. We then propose a software implementation of the floating random walk algorithm that solves the drawbacks in the extraction of capacitances of interconnects in a nonhomogeneous medium as an industrial layout. Finally, experimental and simulation results are presented, validating the adopted approach.

A Versatile Time-Domain Approach to Simulate Oscillators in RF Circuits

This paper presents a versatile simulation technique for the time-domain analysis of RF oscillators. The method blends the superior accuracy and robustness of implicit Runge-Kutta integration formulas with the high efficiency of a particular envelope-following technique. The method can be applied to study both transient and steady-state responses of autonomous and nonautonomous circuits and can also be applied to the case of harsh nonlinear oscillator topologies.

Envelope following method for the transient analysis of electrical circuits

An envelope following method (EFM) that allows efficient transient simulations of electrical circuits is here presented. Its mathematical and electrical bases are considered and the influence of some general properties, such as stability and truncation error of integration methods employed by EFM, are studied. Furthermore, we present a new state variable prediction algorithm that improves previously reported ones, since it better adapts to fast dynamics of the solution. A set of power switching circuits is employed as a benchmark and numerical results of our algorithm are compared to those of conventional integration and of previous EFM versions. Remarkable results are obtained in the electrothermal simulation of power converters where the efficiency gain rises up to some magnitude orders with respect to conventional integration.

Computation of period sensitivity functions for the simulation of phase noise in oscillators

Accurate phase noise simulation of circuits for radio frequency applications is of great importance during the design and development of wireless communication systems. In this paper, we present an approach based on the Floquet theory for the analysis and numerical computation of phase noise that solves some drawbacks implicitly present in previously proposed algorithms. In particular, we present an approach that computes the perturbation projection vector directly from the Jacobian matrix of the shooting method adopted to compute the steady-state solution. Further, we address some problems that arise when dealing with circuits whose modeling equations do not satisfy the Lipschitz condition at least from the numerical point of view. Frequency-domain aspects of phase noise analysis are also considered and, finally, simulation results for some benchmark circuits are presented.