Applications of magnetostrictive materials commonly involve the use of the dynamic deformation, i.e., the piezomagnetic effect. Usually, this effect is described by the strain derivative ∂λ=∂H, which is deduced from the quasistatic magnetostrictive curve. However, the strain derivative might not be accurate to describe dynamic deformation in semihard materials as cobalt ferrite (CFO). To highlight this issue, dynamic magnetostriction measurements of cobalt ferrite are performed and compared with the strain derivative. The experiment shows that measured piezomagnetic coefficients are much lower than the strain derivative. To point out the direct application of this effect, low-frequency magnetoelectric (ME) measurements are also conducted on bilayers CFO=PbðZr; TiÞO 3 . The experimental data are compared with calculated magnetoelectric coefficients which include a measured dynamic coefficient and result in very low relative error (<5%), highlighting the relevance of using a piezomagnetic coefficient derived from dynamic magnetostriction instead of a strain derivative coefficient to model ME composites. The magnetoelectric effect is then measured for several amplitudes of the alternating field H ac , and a nonlinear response is revealed. Based on these results, a trilayer CFO/PbðZr; TiÞO 3 /CFO is made exhibiting a high magnetoelectric coefficient of 578 mV=A (approximately 460 mV=cm Oe) in an ac field of 38.2 kA=m (about 48 mT) at low frequency, which is 3 times higher than the measured value at 0.8 kA=m (approximately 1 mT). We discuss the viability of using semihard materials like cobalt ferrite for dynamic magnetostrictive applications such as the magnetoelectric effect.

Abstract-The proposed innovative manufacturing processdescribed in detail-uses metal foam to create a pressed contact between the top side of a PCB-embedded power die and the rest of the circuit. Initial prototypes were constructed using diodes with die dimensions of 4 mm × 6.35 mm. The prototypes were electrically characterized: the chip and contact DC and AC impedance values were measured and compared with those obtained for conventional packaging that uses bond wires. The electrical impedance of the prototypes was found to be similar to that of a state-of-the-art industrial package. Moreover, the proposed process is simple and cost-effective. Although the results presented in this letter are promising, further research is necessary to fully assess the benefits and limitations of the process.

Abstract-The full integration of DC-DC converters offers great promise for dramatic reduction in power consumption and the number of board-level components in complex systems on chip. Some papers compare the numerous published on-chip and on-die converter structures, but there is the need for an approach to accurately compare the main basic DC-DC conversion topologies. Therefore, this paper presents a method to compare the efficiencies of CMOS integrated capacitive-, inductive-and resonant-based switching converters. The loss mechanism of each structure in hard-switching conditions is detailed and the analytical equations of the power loss and output voltage are given as a function of few CMOS technology parameters. The resulting models can be used to accurately predict converter efficiency in the early design phase, to compare the basic structure in particular the technology node or to orient the passive choice. The proposed method is then applied to design, optimize and compare fully-integrated power delivery requirements on a 1mm 2 on-die area in 65nm CMOS technology over three decades of power density. The results also underline the high efficiency of the promising resonant-based converter.Index Terms-integrated switching power supply, on-chip voltage regulator, switched-capacitor converter, inductive power converter, resonant converter

No abstract

a new process to manufacture low-cost PCBembedded inductor-and transformer-windings is presented in details. Two prototypes are manufactured, one using a conventional technique and the other using our process. The prototypes have similar DC-resistances and inductances but the AC-resistance of the conventional one is up to 3.6 times higher than the other. Using the proposed design in a 28 V to 12 V-5 A buck chopper yields a 5-points increase of the efficiency. In the end, the proposed process is cost-effective and can be implemented on standard PCB manufacturing assembly-lines. It is barely more complicated than the common method, using PCBtracks as windings, but results in much smaller losses.

The temperature distribution in a Silicon Carbide (SiC) MOSFET during a destructive short-circuit is simulated using a custom 1D-finite difference model implemented using Matlab. Some of the main assumptions usually put forward in the literature dealing with this kind of simulations are tested in this paper. We show that some of those simplifications (model of the heat source, die top-side boundary conditions, etc.), sometime in-spite of common sense, have a great impact on the simulated temperature.

A Printed Circuit Board (PCB)-embedding process using pressed metal foam to connect the top-side pads of power dies is considered. The manufacturing process, simple and highly cost-effective, is described in detail; samples are manufactured and their reliability and robustness are characterised. It is shown that thermally cycled prototypes exhibit reliability close to that of Direct Bounded Copper (DBC) substrates. Samples submitted to 150 A-surges have highly scattered reliability. SiC MOSFETs submitted to destructive current limiting tests and repetitive short-circuit tests performed similarly to dies reported in TO247 packages. A discussion on the development of reliability-assessment-methods, especially suited for PCB-embedding processes, is proposed.

No abstract