• Journal of Satellite, Information and Communications
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• v.1 no.1
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• pp.54-58
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• 2006

A new design for easily controlling operating frequency of an antenna-integrated planar oscillator is introduced. The oscillator circuit of a broadband negative-resistance active part and a passive load including a patch antenna. The patch resonance is used for determining the oscillation frequency. This design reduces the possibility of mismatch between antenna radiation and oscillation frequencies. To achieve optimum output power, load-pull simulation for the negative-resistance circuit is used. The load-pull simulation shows the feed point and the delay of feed line can affect the oscillation power. Two negative-resistance circuits capable of supporting oscillation over full C-band and X-band are fabricated. The oscillation frequency, output power and phase noise for different patch antennas are measured.

• Journal of Advanced Navigation Technology
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• v.4 no.1
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• pp.1-10
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• 2000

When the magnetron is employed as a radar transmitter source, the receiver needs to detect the frequency and the phase of the transmitting signal for the coherent operation. The local oscillator frequency is tuned for the stable intermediate frequency and the coherent oscillator generates the stable signal which is phase-locked to the transmitting signal. In this paper, we designed and implemented the receiver front-end including AFC(Automatic Frequency Control) circuit, STALO(Stable Local Oscillator) and COHO (Coherent Oscillator) unit.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.3 s.357
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• pp.26-34
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• 2007

This Paper describes a chip design technique for body composition analyzer based on the BIA (Bioelectrical Impedance Analysis) method. All the functions of signal forcing circuits to the body, signal detecting circuits from the body, Micom, SRAM and EEPROMS are integrated in one chip. Especially, multi-frequency detecting method can be applied with selective band pass filter (BPF), which is designed in weak inversion region for low power consumption. In addition new full wave rectifier (FWR) is also proposed with differential difference amplifier (DDA) for high performance (small die area low power consumption, rail-to-rail output swing). The prototype chip is implemented with 0.35um CMOS technology and shows the power dissipation of 6 mW at the supply voltage of 3.3V. The die area of prototype chip is $5mm\times5mm$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.2
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• pp.85-96
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• 2017

In this paper, a 2~18 GHz wideband 6-port network is designed and fabricated to extend the measurement frequency bandwidth of noise parameter measurement method using 6-port network. In order to design a broadband 6-port network, a wilkinson power divider and a directional coupler with wideband characteristics are designed. The wilkinson power divider is designed as a three-section structure to achieve wideband characteristics. The direction coupler is designed as a three-section structure and slot-coupled structure using multi-layer substrate to obtain wideband characteristics. A wideband 6-port network is designed and fabricated combining the designed power divider and coupler. The measured results of the fabricated 6-port network for the 2~18 GHz band show characteristics applicable to the noise parameter measurement method.

• Electrical & Electronic Materials
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• v.6 no.6
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• pp.554-563
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• 1993

본 연구는 복소유전률 측정장치의 실현을 목표로 한 것이다. 본 장치는 인터페이스 유니트, 외부 RAM, 프로그래머블 카운터, D/A 콘버터, 측정회로, S&H 회로, A/D콘버터 및 기타 제어회로로 구성하였다. 컴퓨터에 의해 여러 종류의 파형이 디지털화하여 생성되며 4096워드의 외부 스태틱 RAM에 전송된다. 이와같이 RAM에 저장된 데이타는 D/A콘버터에 의하여 아날로그 전압파형으로 변환된다. 이 전압파형의 주파수는 클럭펄스에 의한 RAM의 읽기 속도에 좌우된다. 이와같이 생성된 전압파형이 유전체에 인가되며 이 인가전압과 함께 유전체의 응답전압이 샘플링되어 A/D콘버터에 의해 디지털 데이터로 변환된다. 컴퓨터는 응답전압 및 인가전압을 취하게 되며 마지막으로 복소유전률을 계산한다. 본 측정장치의 측정주파수 범위는 0.04Hz-10kHz이다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.10
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• pp.907-913
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• 2015

This work presents a method to predict the near magnetic field distribution on the digital switching circuit mounted on PCB using co-simulation of circuit and electromagnetic fields. The proposed method first obtains the normalized near field distribution by exciting the signal and power ports of the switching circuit using sinusoidal sources. Then the real near magnetic field distribution is determined by weighting the normalized field distribution using the current spectrum of the switching circuit. To confirm the proposed method, a switching IC with a ring oscillator and a output buffer is fabricated and measured in the form of chip-on-board. The surface magnetic field distribution is measured using a magnetic probe above the PCB and compared with the simulation results. Experimental results show the correspondence between simulation and measurement results within 10 dB up to fifth harmonics.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.2
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• pp.35-43
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• 2011

In this paper, an analysis on I/Q mismatch characteristics of a quadrature LC VCO(Voltage controlled oscillator) is presented. Based on this analysis, a new I/Q mismatch compensator is proposed. The proposed I/Q mismatch compensator utilizes an amplitude mismatch detector rather than the conventional phase mismatch detector requiring much more wide frequency bandwidth. To verify the proposed circuit, a 2.5GHz quadrature LC VCO was designed in a $0.18{\mu}m$ CMOS process and tested. Test results show that an amplitude mismatch detector achieves similar I/Q mismatch compensation performance as that of the conventional phase mismatch detector. The I/Q mismatch compensator consumes 0.4mA from 1.8V supply voltage and occupies $0.04mm^2$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1308-1315
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• 2009

A full-polarimetric scatterometer(HPS: Hongik Polarimetric Scatterometer) for X-band is designed, fabricated, and verified using the theoretically well-known point-targets in this paper. The X-band full-polarimetric scatterometer consists of an OMT(Orthogonal-Mode Transducer)+horn antenna, the angle control part for the OMT+horn antenna, a transmitter/receiver with a network analyzer and a frequency-conversion circuitry, and a movable support of these parts. We use an inclinometer sensor to control the vertical and horizontal incidence angles. The full polarimetric data can be obtained because of the polarization switches and the OMT. The accuracy of the scatterometer system is verified by measuring the polarimetric RCS(Radar Cross Section) of one of the theoretically well-known point-targets, i.e., a corner reflector.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.138-138
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• 2010

이중 주파수를 이용한 고주파 용량성 결합 플라즈마 장치는 반도체 및 디스플레이 생산 공정에서 널리 사용되는 장치 형태이며 일반적으로 이온 플라즈마 주파수보다 높은 주파수의 고주파 전력과 이온 플라즈마 주파수보다 낮은 주파수의 저주파 전력을 인가하여 플라즈마 발생 밀도 및 입사 이온 에너지를 독립적으로 조절할 수 있다. 용량성 결합 플라즈마 장치에서는 전극의 쉬스 임피던스가 비선형적으로 변화함에 따라 전극의 전압, 전류 및 플라즈마 전위는 수많은 고조파를 포함하게 되며, 이중 주파수가 인가된 경우 이러한 고주파와 저주파 신호의 고조파가 상호 변조된 형태로 나타나게 된다. 본 연구에서는 주파수에 따른 이온의 거동 특성 차이를 이용하여 변조된 형태의 Lieberman의 비균일 RF쉬스 모델을 가정한 고주파 쉬스를 단순한 저주파 쉬스로 모사하였다. 단순화된 저주파 쉬스 임피던스를 이용한 회로 모델을 구성하여 100MHz와 2MHz RF전력을 사용하는 용량성 결합 플라즈마 장치에서 측정된 전극 전압, 전류 및 플라즈마 전위 신호의 위상차 및 고조파 발생 특성을 분석하였다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.4
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• pp.45-52
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• 1980

In order to eliminate the phase errors caused by the finite GB product of operational amplifiers, novel integnator circuits are proposed. These circuits are characterized by their positive phase error angles and integrator selectivity. The positive sign of the Q and of the circuits compensates the negative selectivity and phase error angles, inherent in the integrated operational amplifiers. Miller inverting intergrator of a biquad circuit realized by Thomas is replaced by the proposed circuit and the band-pass frequency response of the modified biquad network is experimentally analyzed. A considerable improvement is recognized to such extent that the center frequency of the band-pass filter is allowed to be shifted up to 20KHz, which has been infeasible with conventional biquad networks.