Application of Chip-Level EMC in Automotive Product Design

Integrated circuits (ICs) are often the source of the high-frequency noise that drives electromagnetic emissions from electronic products. A case study is presented where emissions from a printed circuit board containing an automotive microcontroller are reduced significantly through analysis of the coupling mechanisms from the chip to the board and attached cables. Noise generated by the IC is explored through measurements in a semi-anechoic chamber and TEM cell, through near-field scans, and through modifications to the printed circuit board. Noise is driven by the IC through both power and I/O connections. Results show that a ferrite in series with I/O power in this application reduced emissions by 10 dB or more at critical frequencies. Possible causes for emissions from the IC and modifications that might reduce these emissions are discussed

Two adjacent mutations on the dimer interface of SARS coronavirus 3C-like protease cause different conformational changes in crystal structure

AbstractThe 3C-like protease of SARS coronavirus (SARS-CoV 3CLpro) is vital for SARS-CoV replication and is a promising drug target. It has been extensively proved that only the dimeric enzyme is active. Here we discovered that two adjacent mutations (Ser139_Ala and Phe140_Ala) on the dimer interface resulted in completely different crystal structures of the enzyme, demonstrating the distinct roles of these two residues in maintaining the active conformation of SARS-CoV 3CLpro. S139A is a monomer that is structurally similar to the two reported monomers G11A and R298A. However, this mutant still retains a small fraction of dimer in solution, which might account for its remaining activity. F140A is a dimer with the most collapsed active pocket discovered so far, well-reflecting the stabilizing role of this residue. Moreover, a plausible dimerization mechanism was also deduced from structural analysis. Our work is expected to provide insight on the dimerization–function relationship of SARS-CoV 3CLpro

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

Integrated circuits switching current modeling, measurement and power delivery network optimization

Switching currents on the Integrated Circuits (ICs) power distribution network (PDN) are very often the ultimate source of a system level electromagnetic interference issue. Modeling and measurement of this switching current are critical for minimizing those problems. The first paper presented the design, fabrication and characterization of a balanced shielded miniature thin-film...The second paper investigated the coupling from IC unbalanced switching current to the TEM cell...The third paper presented a full chip level IC PDN model to predict the switching current behavior at chip level --Abstract, page iv

FDTD modeling incorporating two-port networks and planewave sources in a three dimensional space

Finite Differential Time Domain (FDTD) method has gained increasing interest in modeling of many electromagnetic engineering problems in recent years. It proves to be a reliable numerical modeling tool for electromagnetic modeling, desirable for evaluating EMC performance evaluation, PCB design, antenna design, etc. In this work, new features are developed to extend the modeling ability of the conventional FDTD method. --Abstract, page iii

A Current Probe for Measuring the Individual Ball Current in a Ball-Grid-Array Packaged Device

A current probe was designed to measure ball currents in a Ball-Grid-Array (BGA) package via magnetic induction. This probe, which is based on a Rogowski coil structure, is manufactured in a four-layer flex circuit. Very tiny feature sizes, such as 2 mil buried micro vias and 2 mil trace widths/clearances, push the limit of the flex-circuit fabrication process technology. This design allows the current of a ball in a 1-mm pitch BGA package to be measured. It can also be migrated to package with smaller pitch if the fabrication process allows. This probe is practical for engineering applications as a result of three major advantages. It operates in a broadband from 10 to 3 GHz. The probe can be relocated to different balls and no special printed circuit board is needed. The probe shows acceptable shielding effectiveness of the unwanted fields caused by adjacent balls or sources. In conjunction with both a differential amplifier and an active oscilloscope probe, the output signal is sufficiently amplified to overcome the noise figure of the oscilloscope. This allows time domain measurements. Moreover, a frequency-domain data processing program was developed for correcting the probe\u27s frequency response and reconstructing the time domain waveform. The probe is validated against analytical calculation, and full-wave simulation; it is characterized with the aid of circuit modeling. The probe\u27s functionality is finally demonstrated with a field-programmable-gate-array test board

Copper Sulfide Remobilization and Mineralization during Paleoproterozoic Retrograde Metamorphism in the Tongkuangyu Copper Deposit, North China Craton

International audienceThe Tongkuangyu copper deposit, North China Craton, is hosted in a volcano-sedimentary sequence (ca. 2.2 Ga) that metamorphosed to the lower amphibolite facies at ca. 1.9 Ga. Petrographic observations revealed various metamorphic fabrics (mineral alignment and foliations) and several generations of biotite, chlorite, and pyrite. Sulfide Pb-Pb dating indicates that copper mineralization occurred at 1960+46/−58 Ma, younger than the zircon U-Pb age of the host metatuff (2180 Ma to 2190 Ma), but close to the timing of regional metamorphism (ca. 1.9 Ga). Electron probe analyses show that the biotites belong to the magnesium-rich variety, and were formed at 470 to 500 • C based on Ti-in-biotite thermometry. Chlorites belong to ripidolite and pycnochlorite, and were formed at ca. 350 • C based on the Al geothermometer. Pyrites in porphyry, metatuffs, and quartz veins have contrasting Ni and Co concentrations, pointing to a local remobilization. Hydrogen and oxygen isotopic analyses suggest that biotite and chlorite were formed by metamorphic waters whereas quartz records much lower δD f luid values, reflecting the influence of meteoric water. Fluid inclusions in pyrite and chalcopyrite in metatuff and quartz vein contain extremely radiogenic 4 He and 40 Ar, indicating a crustal origin for the fluids. Sulfides show a magmatic sulfur isotopic signature, likely indicating the presence of preexisting volcanism-related sulfides. We proposed that the early layered copper sulfides formed during metamorphic retrogression at ca. 1.9 Ga and the late vein-type sulfides were derived from the remobilization of the earlier sulfides by infiltration of external fluids such as residual seawater and metamorphic fluids at shallow level

Unbalanced Currents in Integrated Circuits and their Effect on TEM Cell Emissions

Transverse ElectroMagnetic (TEM) cell measurements are often used to evaluate the potential of ICs to cause radiated emissions in printed circuit boards. These measurements are a function of the unbalanced current on package power pins, for example, where more current enters one side of an IC than another, and the displacement current caused by capacitive coupling from the power grid mesh to the septum of the TEM cell. The relationship between unbalanced currents and TEM cell measurements is derived in this paper. A distributed model of the on-die power delivery network is developed to show that unbalanced currents may be caused by an asymmetric power pin arrangement, by an imbalance in package impedance, or by an imbalance in the impedance of the on-die power delivery network. To validate results, the magnitude and phase of high-frequency power-pin currents were measured on a test chip. Experiments showed that results could be used to guide modifications to the chips connection to the printed circuit board power structure to minimize unbalanced currents and, thus, to minimize TEM cell measurements

Aerosol Characterization of Northern China and Yangtze River Delta Based on Multi-Satellite Data: Spatiotemporal Variations and Policy Implications

Horizontal and vertical distributions of aerosol properties in the Taklimakan Desert (TD), North central region of China (NCR),North China Plain(NCP), and Yangtze River Delta (YRD) were investigated by statistical analysis using Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) L3 data from 2007 to 2020, to identify the similarities and differences in atmospheric aerosols in different regions, and evaluate the impact of pollution control policies developed in China in 2013 on aerosol properties in the study area. The aerosol optical depth (AOD) distribution had substantial seasonal and spatial distribution characteristics. AOD had high annual averages in TD (0.38), NCP (0.49), and YRD (0.52). However, these rates showed a decline post-implementation of the long-term pollution control policies; AOD values declined by 5%, 13.8%, 15.5%, and 23.7% in TD, NCR, NCP, and YRD respectively when comparing 2014–2018 to 2007–2013, and by 7.8%, 11.5%, 16%, and 10.4% when comparing 2019–2020 to 2014–2018. The aerosol extinction coefficient showed a clear regional pattern and a tendency to decrease gradually as height increased. Dust and polluted dust were responsible for the changes in AOD and extinction coefficients between TD and NCR and NCP and YRD, respectively. In TD, with change of longitude, dust aerosol first increased and then decreased gradually, peaking in the middle. Similarly in NCP, polluted dust aerosol first increased and then decreased, with a maximum value in the middle. The elevated smoke aerosols of NCP and YRD were significantly higher than those observed in TD and NCR. The high aerosol extinction coefficient values (>0.1 km−1) were mainly distributed below 4 km, and the relatively weak aerosol extinction coefficients (>0.001 km−1) were mainly distributed between 5–8 km, indicating that the high-altitude long-range transport of TD and NCR dust aerosols affects NCP and YRD