• Journal of electromagnetic engineering and science
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• v.5 no.1
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• pp.8-13
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• 2005

The InGaP/GaAs hetero-junction bipolar transistor(HBT) monolithic voltage-controlled dielectric resonator oscillator(VCDRO) is first demonstrated for a Ku-band low noise block down-converter(LNB) system. The on-chip voltage control oscillator core employing base-collector(B-C) junction diodes is proposed for simpler frequency tuning and easy fabrication instead of the general off-chip varactor diodes. The fabricated VCDRO achieves a high output power of 6.45 to 5.31 dBm and a wide frequency tuning range of ]65 MHz( 1.53 $\%$) with a low phase noise of below -95dBc/Hz at 100 kHz offset and -115 dBc/Hz at ] MHz offset. A]so, the InGaP/GaAs HBT monolithic DRO with the same topology as the proposed VCDRO is fabricated to verify that the intrinsic low l/f noise of the HBT and the high Q of the DR contribute to the low phase noise performance. The fabricated DRO exhibits an output power of 1.33 dBm, and an extremely low phase noise of -109 dBc/Hz at 100 kHz and -131 dBc/Hz at ] MHz offset from the 10.75 GHz oscillation frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.161-166
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• 2005

The synthesis procedure of Marchand balun using planar coupled-line is presented. The design limitations of this type of balun have been described before its synthesis procedure. The balun has equi-ripple passband responses and balanced output without fourth balanced transmission line which is difficult to implement with conventional planar topology. As an example, 2:1 Marchand balun is designed and its momentum simulation result show good verification fur this methodology.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.140-144
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• 2004

The selectable dual band LNA usually uses common source transistor pair each input of which is selectively driven at a different frequency in a series resonant form. This paper analyzes the degradation in noise figures of the MOSFET common source pair with series resonance when it is driven concurrently at both inputs with different frequencies as a concurrent dual band LNA. Results of analysis will be compared with the measured noise figures of CMOS LNA with double inputs fabricated in 0.18 $\mu\textrm{m}$ CMOS process. Additionally, analyzing the contributions of FET channel noise and source noise from the LNA operating in the other band, this paper proposes optimum matching topology which minimizes the added noises for concurrent operation.

• Journal of electromagnetic engineering and science
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• v.9 no.1
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• pp.7-11
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• 2009

An Ultra-WideBand(UWB) Low-Noise Amplifier(LNA) is proposed and is implemented in a $0.18-{\mu}m$ CMOS technology. The proposed UWB LNA provides excellent wideband characteristics by combining a High-Pass Filter (HPF) with a conventional resistive-loaded LNA topology. In the proposed UWB LNA, the bell-shaped gain curve of the overall amplifier is much less dependent on the frequency response of the HPF embedded in the input stage. In addition, the adoption of fewer on-chip inductors in the input matching network permits a lower noise figure and a smaller chip area. Measurement results show a power gain of + 10 dB and an input return loss of more than - 9 dB over 2.7 to 6.2 GHz, a noise figure of 3.1 dB at 3.6 GHz and 7.8 dB at 6.2 GHz, an input PldB of - 12 dBm, and an IIP3 of - 0.2 dBm, while dissipating only 4.6 mA from a 1.8-V supply.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.748-753
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• 2002

In this paper, a new topology of a active capacitor is proposed in order to apply the resonator in the design of RF active bandpass filters. Through the noise analysis of the active capacitor, the optimized low noise design process is also presented, Due to the low noise performance of the proposed active bandpass filter, it can be used in the RF front-end of the receivers. In designed 2-stage active bandpass filter at 1.9 GHz shows insertion loss of 0 dB, noise figure of 2.6 dB, and OIP3 of 8 dBm.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.2
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• pp.15-22
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• 2013

Low-Temperature-cofired ceramics (LTCC) antenna packages have been extensively researched and utilized in recent years due to its excellent electrical properties and ease of implementing dense package integration topologies. This paper introduces some of the key research and development activities using LTCC packaging solutions for 60 GHz antennas at Samsung Electronics [1]. The LTCC 60 GHz antenna element topology is presented and its measured results are illustrated. However, despite its excellent performance, the high cost issues incurred with LTCC at millimeter wave (mmWave) frequencies for antenna packages remains one of the key impediments to mass market commercialization of mmWave antennas. To address this matter, for the first time to the author's best knowledge this paper alleviates the high cost of mmWave antenna packaging by devising a novel, broadband antenna package that is wholly based on low-cost, high volume FR4 Printed Circuit Board (PCB). The electrical properties of the FR4 substrate are first characterized to examine its feasibility at 60 GHz. Afterwards a compact multi-layer antenna package which exhibits more than 9 GHz measured bandwidth ($S_{11}{\leq}-10$ dB) from 57~66 GHz is devised. The measured normalized far-field radiation patterns and radiation efficiency are also presented and discussed.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1980-1990
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• 2017

A study on the multi-objective optimization of Interior Permanent-Magnet Synchronous Motors (IPMSMs) with 2, 3, 4 and 5 flux barriers per magnetic pole, based on Genetic Algorithm (GA) is presented by considering the aspect of irreversible demagnetization. Applying the 2004 Toyota Prius single-layer IPMSM as the reference machine, the asymmetrical two-, three-, four- and five-layer rotor models with the same amount of Permanent-Magnets (PMs) is presented to improve the torque characteristics, i.e., reducing the torque pulsation and increasing the average torque. A reduction of the torque pulsations is achieved by adopting different and asymmetrical flux barrier geometries in each magnetic pole of the rotor topology. The demagnetization performance in the PMs is considered as well as the motor performance; and analyzed by using finite element method (FEM) for verification of the optimal solutions.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.8
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• pp.482-492
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• 2002

This paper deals with overvoltage stresses in the field circuit of synchronous machine connected to HVDC terminal. A load rejection of the HVDC may cause generator in the station to become self-excited, resulting in a severe system overvoltage. This paper shows that violent field current oscillations can be produced by resonance between the machine inductance and the terminal capacitance. As most conventional excitation system do not allow reverses current, new topology of excitation system to allow reverse current is proposed. the proposed system can limit the rate of rise of terminal voltage during conditions of self excitation. Apart from these simulations, the nature(Magnitude and frequency) of the field transient state is explained mathematically. Finally, the EMTDC program is used for the simulation studies.

• Transactions on Electrical and Electronic Materials
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• v.18 no.1
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• pp.16-20
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• 2017

A RF-MEMS (radio-frequency microelectromechanical-system) based DPDT (double pole double throw) switch for the Ku band has been designed and analyzed for this article. The switch topology is based on the FG-CPW (finite ground-coplanar waveguide) configuration of a microstrip-transmission line. An FEM-based multiphysics solver is used for the evaluation of the spring constant, stress distribution, and pull-in voltage regarding the requirements of the switch-beam unit. The electromagnetic performance of the switch is investigated for a $675{\mu}m$ thick silicon substrate. For the operational frequency of 14.5 GHz, an insertion loss better than -0.3 dB, a return loss better than -40 dB, and input/output- and output-port isolations better than -35 dB are achieved for the switching unit.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1669-1677
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• 2016

A new auxiliary circuit for boost, buck, buck-boost, Cuk, SEPIC, and zeta converters is introduced to provide soft switching for pulse-width modulation converters. In the aforementioned family of DC-DC converters, the main and auxiliary switches turn on under zero current transition (ZCT) and turn off with zero voltage and current transition (ZVZCT). All diodes commutate under soft switching conditions. On the basis of the proposed converter family, the boost topology is analyzed, and its operating modes are presented. The validity of the theoretical analysis is justified by the experimental results of a 100W, 100 kHz prototype. The conducted electromagnetic emissions of the proposed boost converter are measured and found to be lower than those of another ZCT boost converter.