54 research outputs found
A Critical Review of Techniques for the Experimental Extraction of the Thermal Resistance of Bipolar Transistors from DC Measurements—Part II: Approaches Based on Intersection Points
No full textThis work constitutes Part II of a comprehensive three-part study critically reviewing techniques for the indirect extraction of the thermal resistance in bipolar transistors using simple DC current/voltage measurements. While Part I focused on thermometer-based methods, this study examines techniques that rely on intersection points between electrical characteristics. The accuracy of these methods is assessed by applying them to DC curves obtained through PSPICE simulations of an in-house transistor model incorporating nonlinear thermal effects, and comparing the extracted thermal resistance data with the thermal resistance formulation embedded in the model. An InGaP/GaAs HBT and a Si/SiGe HBT for high-frequency applications are considered as case-studies. The analysis highlights key drawbacks affecting the methods, including theoretical approximations and sensitivity to the selection of intersection points. Among the techniques examined, only one adequately accounts for the nonlinear thermal behavior, though its original formulation presents practical limitations. To tackle this problem, we propose an improved and refined version of the approach that offers enhanced accuracy at the cost of increased complexity
Circuit-Based Electrothermal Simulation of Multicellular SiC Power MOSFETs Using FANTASTIC
No full textThis paper discusses the benefits of an advanced highly-efficient approach to static and dynamic electrothermal simulations of multicellular silicon carbide (SiC) power MOSFETs. The strategy is based on a fully circuital representation of the device, which is discretized into an assigned number of individual cells, high enough to analyze temperature and current nonuniformities over the active area. The cells are described with subcircuits implementing a simple transistor model that accounts for the utmost influence of the traps at the SiC/SiO2 interface. The power-temperature feedback is emulated with an equivalent network corresponding to a compact thermal model automatically generated by the FANTASTIC tool from an accurate 3D mesh of the component under test. The resulting macrocircuit can be solved by any SPICE-like simulation program with low computational burden and rare occurrence of convergence issues
Numerical Analysis of the Thermal Impact of Ceramic Materials in Double-Sided Cooled Power Modules
No full textNumerical simulation and analytical modeling of the thermal behavior of single- and double-sided cooled power modules
No full textThis article presents the detailed thermal analysis and modeling of multichip power modules (PMs). For the first time, a fair thermal comparison between the widespread single-sided cooled (SSC) technology and the innovative double-sided cooled (DSC) one is presented. The latter solution emerges among all packaging techniques due to its improved electrical performances and mechanical reliability. The investigation is carried out using 3-D finite-element method thermal simulations automated by an in-house routine. The PMs under test are thoroughly studied in a wide range of boundary conditions (BCs) in order to support the choice of an appropriate cooling strategy and the comprehension of the heat spreading (HS) effect occurring in such domains. In addition, attention is paid to dynamic behavior. Thermal modeling strategies are then proposed and discussed. As the main finding, no relevant thermal discrepancies were observed in the two PM technologies. In most of the BCs, the SSC PM enjoys an enhanced HS effect leading to a better thermal behavior with respect to the DSC counterpart, the adoption of which is justified only in the presence of excellent cooling systems
Boosting the thermal stability of paralleled GaAs HBTs through temperature-dependent ballasting resistors: A proof-of-concept study
No full textOptimum thermal design of high-voltage double-sided cooled multi-chip SiC power modules
No full textThis paper focuses on the thermal investigation of SiC-based power modules with the purpose to support their design in terms of cooling techniques and material choices. The analyses are aimed to compare the widespread single-sided cooling technology with an innovative double-sided cooling variant. The comparison is carried out by simulating extremely detailed 3-D FEM structures realized through an in-house routine developed to automatically perform extensive simulation sessions. First, the effects of convective boundary conditions on the thermal resistance and the heat spreading mechanism are thoroughly examined in both technologies; then, the role of ceramic layers composing the power module substrate is evaluated and quantified in terms of thermal performances
On-Chip Spike Detection and Classification using Neural Networks and Approximate Computing
No full textNeural ensembles control sensory, motor, and cognitive functions. Action potentials of neuronal cells (spikes) may signify such functions, or the presence of a pathology. In this paper we give the circuital implementation of an Artificial Neural Network, able to sort (detect and classify) spikes in real time. The system is synthesized targeting a 14nm FinFET technology. To partially alleviate the computational burden, approximate computing methods have been integrated during the inference stage, yielding up to 63% reduction in dynamic power. The different versions of the circuit reach an accuracy range from 65% to 93%, with silicon area and power that range from 2000μm 2 , 0.1μW@30kHz to 6000μm 2 , 0.7μW@30kHz. The electrical performances of the proposed circuit overcome the state of the art of spike detection circuits while providing the additional feature of spike sorting in a single integrated solution
In-situ extraction of the thermal impedance of GaN power HEMTs embedded in PCB-based power circuits
No full textThis paper validates an innovative thermal impedance (Z(TH)) extraction technique against a state-of-the-art GaN-based power HEMT embedded in a PCB-based power circuit. Differently from traditional approaches based on direct or indirect temperature measurements, the technique provides the junction-to-ambient Z(THj-a)- that is, the in-situ Z(TH) - without any need for (i) thermocouples/infrared cameras or (ii) specific equipment like thermochuck and cold-plates. The accuracy of the technique is assessed by adopting the `simulated experiments' strategy: the technique is applied to calibrated electrothermal simulations emulating the experiments, and the extracted junction-to-ambient Z(TH) is successfully compared to a reference one preliminarily determined with numerical simulations
Optimum module design I: electrothermal
No full textSilicon carbide (SiC) power transistors often operate under critical conditions with a large amount of heat generation, which may lead to reliability degradation or even to an irreversible device failure in harsh cases. As a consequence, reliable simulation tools accounting for electrothermal (ET) effects are highly desired to define the thermal dissipation constraints and optimize the design of the transistor layout and/or of the cooling system. However, this task is far from trivial due to multiple reasons: (i) trustworthy ET simulations of SiC transistors can in principle be obtained only by using device models that accurately describe the key physical parameters and their temperature dependences, which are rather different compared with traditional silicon devices; (ii) the tools must be suited to describe also temperature and current nonuniformities, which are often responsible for the safe operating area shrinking of multicellular transistors; (iii) it is obvious that 3-D approaches accounting for the distributed heat dissipation (i.e., for a sufficiently high number of heat sources) over the geometrically complex power device can be very resource-hungry and prone to convergence failures, especially if dynamic simulations under critical conditions have to be performed. In this chapter, an innovative approach is proposed, the aim of which is to optimize the trade-off between computational efficiency and accuracy when handling problems with a relatively large amount of heat sources. The proposed strategy relies on a fully circuital representation of the whole device, wherein the equivalent network emulating the power-temperature feedback is obtained from a dynamic compact thermal model (DCTM), in turn automatically derived from an exceptionally accurate finite-element method (FEM) description of the device. A multicellular 4H-SiC power MOSFET operated under dc, short-circuit (SC), and unclamped inductive switching (UIS) conditions is considered as a case study
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