Sukjin Kim

Preparation of polythiophene LB films and their gas sensitivities by the ouartz crystal microbalance

Abstract The gas sensitivity of polythiophene LB film was investigated. As polythiophene has the conjugated double bond, the potential applications to the various devices using its conducting property have been proposed. The Langmuir-Blodgett(LB) technique has been used to manipulate conducting polymers to multilayer thin films with well defined structures and ordered molecular orientations. In this study, we have synthesized the polythiophene derivatives such as poly(octyl thiophene)(POT), poly(propanoate thiophene)(PEPT) and poly(decanoate thiophene)(PEDT), and observed their behaviors at the air/water interface. For the preparation of polythiophene LB films with good quality, we have used the mixed monolayer with surface active materials like octadecylamine(ODA) and controlled the subphase conditions. Also, for the application to the sensing materials, we have tested the gas sensitivities of polythiophene derivatives LB films to NO 2 gas by the quartz crystal microbalance(QCM).

Electromagnetic radiated emissions from a repeating-coil wireless power transfer system using a resonant magnetic field coupling

Wireless power transfer technologies have been studied steadily and reached the stage of practical use in recent years. As the commercialized research on the wireless power transfer have been performed, the wireless power transfer system utilizing the repeating-coil have been attempted. Then, the electromagnetic radiated emissions have become an important issue. In this paper, we report the measurement and analysis of the electromagnetic radiated emissions from the repeating-coil wireless power transfer system using a resonant magnetic field. A relationship between the resonance and the transferred power are analyzed with respect to the impedance profile obtained from analytical expressions, simulations and measurements. The results show that the electromagnetic radiated emissions are enhanced at the series resonance peaks of the impedance profile in the repeating-coil wireless power transfer system using a resonant magnetic field coupling in the case of a constant-voltage AC source.

Electromagnetic interference shielding effects in wireless power transfer using magnetic resonance coupling for board-to-board level interconnection

In this paper, we present the analysis of electromagnetic interference (EMI) shielding effects of wireless power transfer (WPT) using magnetic resonance coupling for board-to-board level interconnection. Board-to-board WPT consists of source coil, receiver coil, and load which are manufactured on printed circuit board (PCB). The coil is expressed as a simple equivalent circuit model, of which the components are calculated using the physical dimensions of the coil. It is verified that the results of model estimation in both frequency- and time-domain show a good correlation with simulated and measured results under 1GHz. Voltage transfer ratio (VTR) of board-to-board WPT was achieved to be 0.49. In addition, EMI shielding effects in WPT with materials such as ferrite and metal film is analyzed using verified model. The shielding effects of each film in WPT are compared by observing their magnetic field distribution.

Contactless wafer-level TSV connectivity testing method using magnetic coupling

With the advent of 3D-IC, Through Silicon Via (TSV) has been highlighted as the key technology for compactly integrating dies of various functions. However, due to the instability in the TSV fabrication process, various types of failure can be resulted, resulting in drastic decrease in the final chip yield with the increase in the number of TSVs and stacked dies. In this paper, we propose a novel contactless wafer-level TSV connectivity testing structure that can detect TSV defects on wafer-level, while overcoming the limitations of the conventional direct probing method. TSVs are aligned and connected as to enable the detection of change in the series capacitance between adjacent TSVs for verification of the TSV defects. Through time- and frequency-domain simulation results, we verified that the proposed structure can successfully detect TSV defects.

High-Efficiency PCB- and Package-Level Wireless Power Transfer Interconnection Scheme Using Magnetic Field Resonance Coupling

As technology develops, the number of chips increases while the thickness of mobile products continuously decreases, which leads to the need for high-density packaging techniques with high numbers of power and signal lines. By applying wireless power transfer technology at the printed circuit board (PCB) and package levels, the number of power pins can be greatly reduced to produce more space for signal pins and other components in the system. For the first time, in this paper, we propose and demonstrate a high-efficiency PCB- and package-level wireless power transfer interconnection scheme. We enhance the efficiency by applying magnetic field resonance coupling using a matching capacitor. The proposed scheme can replace a high number of power interconnections with rectangular spiral coils to wirelessly transfer power from the source to the receiver at the PCB and package levels. The equivalent circuit model is suggested with analytic equations, which is then analyzed to optimize the test vehicle design. For the experimental verification of the suggested model, the

Design, implementation and measurement of board-to-board wireless power transfer (WPT) for low voltage applications

Z

Modeling and analysis of defects in through silicon via channel for non-invasive fault isolation

-parameter results obtained from the model-based equation and measurement of the designed and fabricated test vehicles are compared at up to 1 GHz. The power transfer efficiency from the source coil to the receiver coil in this scheme is able to reach 85.6%. Finally, we designed and fabricated a CMOS full-bridge rectifier and mounted it on the receiver board to convert the transferred voltage from ac voltage to dc voltage. A measured dc voltage of 2.0 V is sufficient to operate the circuit, which generally consists of 1.5 V devices.

Noise Coupling Effects on CMOS Analog-to-Digital Converter in Magnetic Field Wireless Power Transfer System Using Chip-PCB Comodeling and Simulation

In this paper, we present measurement results of board-to-board wireless power transfer (WPT) for low voltage applications using resonant coupling. WPT system consists of source coil, receiver coil, rectifier and load on printed circuit board (PCB). Among them, spiral coil is expressed as a simple equivalent circuit, of which the components are calculated using its physical configurations. The measurement result in frequency-domain shows a good correlation with simulation result using the simple equivalent circuit. In addition, CMOS full bridge rectifier with low turn-on voltage is designed and fabricated to be mounted on PCB. In this system, it is observed that turn-on voltage of the rectifier is very small and DC level at the load is sufficient to be adapted to low voltage applications. Consequently, coil-to-coil voltage transfer ratio (VTR) and DC level at the load of board-to-board WPT are achieved to be 0.50 and 1.32V, respectively. Power transfer efficiency of 30% is calculated using circuit simulation.

Fault detection and isolation of multiple defects in through silicon via (TSV) channel

Through silicon via (TSV) based 3D IC allows lower power consumption, higher system bandwidth, and smaller form factor of electronic devices. In order to design a system with tens of thousands of I/Os, the fabrication process has to be controlled with extremely high precision. With less than 10 micrometers of diameter and several tens of micrometers of pitch, TSVs are susceptible to mechanical and thermal stress. In this paper, we present a non-invasive fault isolation method for high-speed TSV channel using electrical characteristic analysis. A ground signal ground (GSG) type TSV channel is designed and simulated with 3D FEM solver. The structure is analyzed by equivalent circuit model results, which is compared with the results from 3D FEM solver. By analyzing the S-parameter curves, open and short defects are successfully detected and isolated.

Non-contact wafer-level TSV connectivity test methodology using magnetic coupling

Analog-to-digital converter (ADC) is becoming of utmost importance in an automotive environment. With the increased number of magnetic field sources near the ADC that can alter its behaviors significantly, we need to model how magnetic field affects the performance of the ADC. Therefore, in order to accurately evaluate the practical performance of the ADC and the considerable off-chip and on-chip effects that are highly complex, the chip-printed circuit board (PCB) comodeling, cosimulation, and coanalysis are required. In this study, a comodel of the magnetic field effects on an ADC is proposed. The proposed comodel includes three separate submodels: a model of the magnetic field coupling from the wireless power transfer (WPT) system input to the PCB integrated with ADC, a model of the noise coupling from the PCB to the ADC input, and a model of the ADC behavior from the ADC input to the ADC outputs. Considering the magnetic field coupling from the magnetic field source to the PCB, a new inductive transmission line model (I-TLM) method is developed. This method achieves fast, precise, and broadband estimation of the magnetic field effects in comparison to previous estimation methods. To validate the proposed comodel, an ADC is fabricated using a 0.13-μm complementary metal-oxide semiconductor process and is wire-bonded to the designed PCB for ADC. A PCB-level WPT system is designed and built as the magnetic field source. The performance factor of the ADC is measured by sweeping the WPT system input frequency from 100 kHz to 1 GHz to find out the critical WPT system frequency for the designed ADC with the chip-PCB hierarchical structure. The results estimated by the proposed model correlate well with the full 3-D electromagnetic field simulation and measurement. The proposed modeling procedure reduces the time and computation resource in the design of the chip, package, and PCB to achieve high-quality analog devices or mixed-mode systems, while also providing an intuitive understanding of the radiated noise effect.