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This paper presents the modeling of the electrothermal and electromagnetic behavior in SiC-based multi-chip power modules. The proposed approach is based on a macromodeling technique and is applied to a realistic case-study. Preliminarily, the assembly under analysis was experimentally characterized to estimate its parasitics due to electromagnetic interactions. Extremely fast and efficient electrothermal simulations were then performed in a SPICE-like environment. Parasitics and nonlinear thermal effects were accounted for in simulations at high switching frequencies. Results demonstrate that such an approach can be successfully adopted in the design flow of power modules in any device technology.

In our previous papers we have introduced the Chirped-Pulsed Frequency Modulation technique (C-PFM); it has been used to allow the multiplexing capability of a multipoint Fiber Bragg Grating (FBG) sensor network. In this paper we report some preliminary experimental results, which confirm the theoretical analyses previously obtained. The innovative multiplexing approach, without to increase the complexity of the acquisition system, is able to address up to 10 independent sensing points on a single fiber. The C-PFM technique is based on the amplitude modulation of the emitted signal (pulsed) from the laser source by a chirped frequency signal and on the demodulation of the reflected signal by means of an adaptive filter (that is only a numerical elaboration). The experimental result are here shown and commented in order to define limitations and capabilities of the approach.

Dynamic electro-thermal instabilities of power devices are presented and discussed. These analyses have been made with the aim of examining hot spot onset in power cellular transistors. The temperature distributions are obtained by means of a 3D electro-thermal simulator, and the numerical results are compared with experimental dynamic thermal maps, detected by direct IR radiometric measurements with high spatial and high time resolution. By analyzing both experimental and numerical electrothermal instabilities on power cellular BJTs, we have found that the time dependent thermal distribution is a function of the device under simulation (DUS) layout and also that it is a strong function of the single cell temperature dependent current gain and the thermal interaction between the neighbouring cells.

The cellular power transistors are affected by the socalled hot spot phenomenon, a current crowding within few cells occurring for high power conditions, which decreases the device operating range. The onset of this phenomenon was studied under a wide range of electrical and thermal boundary conditions by means of a fast electro-thermal simulation procedure operating in the steady-state regime and using explicit analytical relationships for the temperature mapping. Furthermore, the results of experimental electrical characterizations performed on some samples were in agreement with the foreseen data.

Optically activated semiconductor devices play a very attractive role in power circuits control applications. In fact, due to the very high galvanic isolation between the control circuit side and the power circuit side, these specific devices can solve the safety problems and eliminate the unintentional switching. In an earlier work, a detailed theoretical and numerical analysis of the BMFET as an optically controlled switch was presented. In this paper, the authors complete the previous analysis by presenting experimental results on the optical switching of various kinds of bipolar mode field effect transistor (BMFET) obtained with a low-power optical source. The BMFETs used are different in design parameters and geometries. The results obtained are in good agreement with the authors' previous theoretical and numerical previsions.