Improving the High-Frequency Attenuation of Shunt Capacitor, Low-Pass Filters

Circuit board mounted, shunt capacitive filters are less effective at high frequencies because of the mutual inductance (M) that exists between the input and output ports. An approximate expression for the mutual inductance is M=(μh/2π)ln(h/a); where h=via length and a=radius of the via connecting the capacitor to the return plane. The reduced mutual inductance associated with the new, three-terminal, surface-mounted capacitor results in more than 15 dB increased attenuation compared to two-terminal capacitors over the 0.3-6.0 GHz range with 50 Ω source and load termination

Development and Application of a High-Resolution Thin-Film Probe

This paper documents the development, characterization, and application of a high-resolution thin-film magnetic-field probe. Probe diameter ranged from 5-μm to 100-μm. The 100-μm probe exhibits a 250-7μm improvement in spatial resolution compared to a conventional loop probe, measured at a height of 250 μm over differential traces with a 118-μm spacing. Electric field rejection was improved using shielding and using a 180-degree hybrid junction to separate common-mode (electric field) and differential-mode (primarily magnetic field) coupling. A network analyzer with narrow band filtering was used to detect the relatively weak signal from the probe and to allow detection of phase information. An application of the probe is demonstrated where the probe is used to identify the magnitude and phase of magnetic fields produced by currents in very closely-spaced IC package pins

Voltage Regulator Module Noise Analysis for High-Volume Server Applications

This paper presents a methodology to analyze voltage regulator module (VRM) noise coupling problems in high-volume server applications. The technique is applied on a real engineering design. The comprehensive model includes irregular power shapes, decoupling capacitors, and dielectric and conductive loss. Irregular shaped power plane modeling is cross-checked with four separate methods to demonstrate accuracy

Overuse of preoperative laboratory coagulation testing and ABO blood typing: a French national study

International audienceBackground: Following publication of guidelines on routine preoperative tests, the French Society of Anaesthesiology and Intensive Care (SFAR), in association with French national public health insurance, conducted a survey to evaluate adherence to guidelines and the economic consequences. Methods: Using the French Hospital Discharge Database and National Health Insurance Information system, tests performed during the 30 days before surgery were analysed for two situations: (1) standard laboratory coagulation tests and ABO blood typing in children able to walk and scheduled for tonsillectomy/adenoidectomy; and (2) ABO blood typing in adults before laparoscopic cholecystectomy, thyroidectomy, lumbar discectomy or breast surgery. Guidelines do not recommend any preoperative tests in these settings. Results: Between 2013 and 2015, a coagulation test was performed in 49% of the 241 017 children who underwent tonsillectomy and 39% of the 133 790 children who underwent adenoidectomy. A similar pattern was observed for ABO blood typing although re-operation rates for bleeding on the first postoperative day were very low (0.12-0.31% for tonsillectomy and 0.01-0.02% for adenoidectomy). Between 2012 and 2015, ABO blood typing was performed in 32-45% of the 1 114 082 patients who underwent one of the four selected procedures. The transfusion rate was very low (0.02-0.31%). The mean cost for the four procedures over the 4 yr period was €5 310 000 (sd €325 000). Conclusions: Standard laboratory coagulation tests and ABO blood typing are still routinely prescribed before surgery and anaesthesia despite current guidelines. This over-prescription represents a high and unnecessary cost, and should therefore be addressed