Alessandro Magnani

FAst Novel Thermal Analysis Simulation Tool for Integrated Circuits (FANTASTIC)

This work describes a Fast novel thermal analysis simulation tool for integrated circuits (FANTASTIC), which is fully automated and relies on an enhanced version of the Multi-Point Moment Matching algorithm. The tool provides a novel equivalent network suitable for use in SPICE-like circuit simulators to perform efficient thermal and electrothermal analyses. FANTASTIC requires much less CPU time and memory storage compared to commercial simulators. The thermal behavior of a state-of-the-art four-finger GaAs HBT is investigated as a case-study.

Analysis of the UIS behavior of power devices by means of SPICE-based electrothermal simulations

Abstract This paper presents an accurate, yet computationally effective, 3-D simulation strategy devised for the UIS analysis of multicellular power transistors, which accounts for electrothermal effects and is based on a circuit representation of the whole device under test. The approach is exploited to examine the correlation between the shape of the avalanche curve of IGBTs and the physical mechanisms occurring during UIS discharging. In particular, an in-depth investigation is performed on a current hopping phenomenon that – although not usually destructive – entails a reduction in both ruggedness and reliability of the device.

Circuit-Based Electrothermal Simulation of Power Devices by an Ultrafast Nonlinear MOR Approach

This paper presents an efficient circuit-based approach for the nonlinear dynamic electrothermal simulation of power devices and systems subject to radical self-heating. The strategy relies on the synthesis of a nonlinear compact thermal network extracted from a finite-element model by a novel model-order reduction method requiring a computational time orders of magnitude lower than conventional techniques. Unlike commonly employed approaches, the proposed network allows reconstructing the whole time evolution of the temperature field in all the points of the domain with high accuracy. Electrothermal simulations are enabled in a commercial SPICE-like simulator by coupling such a network with subcircuits that describe the electrical device behavior by accounting for the temperature dependence of the key physical parameters. As a case study, the dynamic electrothermal analysis of a packaged silicon carbide power MOSFET undergoing a short-circuit test is performed, showcasing the performance of the approach and highlighting the need of including the thermal nonlinearities to achieve reliable results.

Compact Dynamic Modeling for Fast Simulation of Nonlinear Heat Conduction in Ultra-Thin Chip Stacking Technology

A novel nonlinear model order reduction method is proposed for constructing one-port dynamic compact models of nonlinear heat diffusion problems for ultra-thin chip stacking technology. The method leads to models of small state-space dimensions, which allow accurately reconstructing the whole time evolution of the temperature field due to an arbitrary power waveform of practical interest. The approach is also efficient, since the computational time/memory requirements for constructing each dynamic compact model is about one order of magnitude lower than that corresponding to a single 3-D finite element method transient simulation of a nonlinear problem.

Matrix reduction tool for creating boundary condition independent dynamic compact thermal models

A novel matrix reduction method for the efficient and automatic construction of boundary condition independent dynamic compact thermal models having a chosen accuracy, is proposed. The method is implemented in a code which allows constructing boundary condition independent dynamic compact thermal models of any multi-die package modeled within a 3-D commercial mesher. The proposed approach has many advantages with respect to previous approaches in terms of robustness, efficiency, and applicability. The method is validated through the analysis of a dual-flat no-leads 12-leads package.

Parametric compact thermal models by moment matching for variable geometry

In this paper, a novel parametric moment matching technique is proposed for efficiently constructing accurate parametric compact thermal models for variable geometries. This result is achieved by reformulating the heat diffusion equation in a parametric-dependent domain as a heat diffusion equation in a reference domain wherein the geometry is fixed and material parameters are variable. The approach is successfully applied to provide a fast analysis of the influence of the key layout and technology parameters on the thermal behavior of SiGe heterojunction bipolar transistors.

Structure-preserving approach to multi-port dynamic compact models of nonlinear heat conduction

A novel approach for constructing multi-port dynamic compact thermal models of nonlinear heat diffusion in electronic components is presented, extending a technique previously conceived for the one-port case. The approach allows achieving high levels of accuracy even for small state-space dimensions of the model. It is also very efficient since it requires the solutions to a few linear heat diffusion problems in the frequency domain. The multi-port compact models exhibit structure similar to the one-port counterparts and can be used to accurately approximate not only the junction temperatures, but also the whole space-time temperature distribution within the electronic components.

Structure preserving approach to parametric dynamic compact thermal models of nonlinear heat conduction

A novel model order reduction method for the construction of parametric dynamic compact thermal models of nonlinear heat diffusion problems is proposed. The method extends a previous method, recently proposed by the Authors, for the construction of parametric dynamic compact thermal models of linear heat diffusion problems. The method has been validated through the analysis of a simple die in which high levels of non-linearities and large variations of parameters occur.

Dynamic electrothermal simulation of photovoltaic plants

This paper presents a fast and accurate approach for the dynamic electrothermal analysis of photovoltaic (PV) plants with a cell-level discretization. A circuit model is developed for the elementary cell, and an equivalent electrical network is automatically built in a preprocessing stage to account for the power-temperature feedback. The PV plant under analysis is represented as an electrical macrocircuit that can be solved with low CPU/memory requirements and without convergence issues by using any SPICE-like simulator. The proposed strategy can be successfully exploited for diagnostic purposes.

Analysis of the Influence of Layout and Technology Parameters on the Thermal Impedance of GaAs HBT/BiFET Using a Highly-Efficient Tool

This work is focused on the analysis of the dynamic thermal behavior of advanced GaAs HBTs, with particular emphasis on BiFET technologies, where pHEMTs are integrated below the conventional bipolar device. A novel highly-efficient tool is employed to determine the influence on the thermal impedance of the key layout and technology features, namely, size of the emitter and base-collector mesa, pHEMT layers, and metallization architecture. The tool relies on the multi-point moment matching algorithm, and allows CPU time and memory storage much lower than those required by commercially-available numerical software packages.