Design procedure for reduced filter size in a buck converter using a 4th-order resonance filter

This article presents a novel design procedure for 4th order and 4th order resonance (4thRes) output filters, for given buck converter specifications, making components selection a straightforward process. An accurate filter analysis is provided to predict the filter component currents and voltages in both frequency and time domains. Application of the analysis in a design study of a 20 MHz, 5.4 W buck converter shows that the 4thRes filter has the potential to reduce the output passive components for a wide duty cycle range. As compared with a 2nd order filter at V IN = 6.6 V to V OUT = 1.8 V, total inductance, inductor energy, capacitance, and capacitor energy are 58%, 35%, 45%, and 31% lower, respectively. Air-core PCB integrated solenoid inductors are considered for implementation and testing within a prototype converter to show the impact of these filters on the converter performance. The 4thRes filter achieved 3.7% and 3.6% higher full-load efficiency than the 2nd and 4th order filters, respectively, and a better load transient performance

Degradation of electroless Ni(P) under-bump metallization in Sn3.5Ag and Sn37Pb solders during high-temperature storage

The interfacial reaction between electroless Ni(P) under-bump metallization (UBM) and solders is studied. A P-rich layer forms in the UBM along the solder side after reflow and thermal aging. Crack formation inside the P-rich layer can sometimes penetrate throughout the entire UBM layer structure. The Ni(P) UBM degradation occurs earlier in the Sn3.5Ag solder than in Sn37Pb because of its higher reflow temperature. Despite the formation of a P-rich layer and cracks inside the UBM, it still keeps its original function within the high-temperature storage period in this study. Explanations for the formation of the P-rich layer and cracks in the UBM are outlined along with explanations for the Ni(P) UBM degradation process

Analytical expressions for inductances of 3D air core inductors for integrated power supply

This work presents analytical expressions for the DC inductance of 3D air core inductors with circular cross section pillars (CCSP) and rectangular cross section pillars (RCSP). We consider the following four types of inductor structures: (1) a toroid with CCSP; (2) a toroid with RCSP; (3) a solenoid with RCSP; and (4) a solenoid with CCSP. For each type, a unique analytical model is developed for obtaining DC inductance. High frequency (1-100 MHz) effects on inductance are also discussed. The inductance values predicted by the proposed analytical models of the first three types of inductor structures are in an acceptable agreement with numerical Finite Element Analysis (FEA) solutions, where the maximum difference is 7.3%. Also, our analytical model for the fourth type inductor reduces the error, when correlated with FEA inductance value, up to 6× compared to previously published models. A comparison of results using proposed analytical expressions with published measured values as well as our measurement data demonstrates error ranging from 0.5 to 16.2%, while conventional formulae show errors of up to 143%. The results of the proposed models could serve as a good initial estimate for power supply on chip (PwrSoC) and power supply in package (PSiP) applications

[Review] Cian Duffy (2014) My purpose was humbler, but also higher: Thomas De Quincey’s 'System of the heavens’, popular science and the sublime

Review of article: Duffy Cian, Romanticism, Volume 20 Issue 1, Page 1-14, ISSN 1354-991x Available Online Mar 201

Mount Etna

An overview of the cultural significance of Etna during the eighteenth century and Romantic period

Conference Report : Danish Romanticism Takes to the Hills

A report on a panel convened by the Nordic Association for Romantic Studies at the 'Romanticism Takes to the Hills' conference at Edge Hill University (UK), 29 April 201