• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.439-440
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• 2008

A high-speed DCO is proposed that uses the negative-skewed delay scheme. The DCO consists of a ring of inverters with each PMOS transistor driven from the output of 3 earlier stage through a set of minimum-sized pass-transistors. The digitization of negative-skewed delay is achieved by selecting pass-transistors turned on and digitizing the gate voltages of the selected pass-transistors. The proposed 7-stage DCO has been simulated using 1.8V, $0.18\;{\mu}m$ TSMC CMOS process to obtain a resolution of 3ps and an operation range of 2.88-5.03GHz.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.77-81
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• 2002

This paper demonstrates a CMOS downconversion mixer for 2.4GHz ISM band applications. The mixer, implemented in a 0.18um CMOS process, is based on the CMOS Gilbert Cell mixer, With a 2.5GHz local oscillator and a 2.45GHz RF input, the measurement results exhibit power conversion gam of -6dB, IIP3 of -6dBm, input $P_{-1dB}$ of -15 dBm, and power dissipation in mixer core of 2.7 mW with 0㏈m LO power and 1.8V supply voltage.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.1
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• pp.74-81
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• 2004

We propose a novel scheme to transmit high center frequency RF signals using electroabsorption devices (EADs) as frequency converters at the transmitter and the receiver. In this approach frequency heterodyning is employed for obtaining high center frequency. With the EAD as a detector/mixer at the receiver we demonstrated a smaller conversion loss than that of the conventional modulator/mixer. With EAD as a modulator/mixer at the transmitter and with two heterodyned lasers to generate an optical local oscillator (LO), we demonstrated a large reduction (${\sim}23dB$) in conversion loss, and the transmission is not limited by the optical saturation of the EAD. This transmission scheme has optical single-side-band transmission feature which greatly relieves the fiber dispersion effect.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.235-238
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• 2001

단일 단말기로부터 멀티 통신이 가능하게 됨에 따라 광대역 또는 듀얼대역에서 사용되는 RF 소자 개발이 중요시되고 있다. 그러므로 소형, 저 비용의 멀티대역 VCO(Voltage Controlled Oscillator)개발이 요구된다. 본 논문에서 GSM/DCN 대역에서 사용 가능한 듀얼밴드 VCO을 설계하였다. 하나의 발진부, 듀얼 공진부, 완충증폭기, 스위치회로로 구성되었으며, 위상 보정 기법을 이용하여 각 밴드에 대한 발진 조건을 만족시키므로 사용 부품의 수를 줄일 수 있어 저 비용, 소형화, 낮은 위상잡음(phase noise)을 얻을 수 있다. 설계된 듀얼 VCO는 GSM 대역에서 -110dBc/Hz(100kHz offset) 이하의 위상 잡음과 DCN 대역에서 -108dBc/Hz(100kHz offset)의 위상 특성을 보인다. 출력전력은 0$\pm$3dBm이며 소비전력 7mA로 만족할만한 성능을 보인다.

• Journal of electromagnetic engineering and science
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• v.13 no.4
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• pp.208-213
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• 2013

This paper proposes a tag antenna for radio frequency identification (RFID) food system. The RFID tag antenna is designed and fabricated based on the rectangular loop concept used in the UHF band (Korean and Japanese standards, 916.7-923.5MHz). The proposed tag antenna is composed of a radiation patch, sensor tag chip, temperature sensor, oscillator, and battery. We conjugated matching between the tag antenna and the sensor tag using a U-shaped stub. Details of the proposed tag antenna design and the simulated and measured results are presented and discussed.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.11
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• pp.58-65
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• 1993

The Ku-band GaAs MESFET mixer is designed and implemented using the LINMIC+, the microwave CAD simulator. The RF and IF is 14.0GHz and 1.0GHz, respectively. P$_{LO}$ is 0dBm, it can be obtained 5.8dB of the minimum noise figure at 1.4GHz and 5.8dB of the maximum conversion gain at 1.45GHz. Effects of bias and power level of local oscillator frequency are observed and the characteristics are verified.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.149-152
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• 2005

본 논문은 디지털 마이크로파 다수 반송파 시스템에 적용되는 고안정 국부발진기의 위상잡음에 대해서 분석하였다. 위상잡음의 영향을 분석하기 위해 Lorantizan모델을 사용하여 위상잡음 분산값을 구하였으며, 기저대역 I, Q채널에서 BER과의 특성을 모의실험 하였다. 시스템에 미치는 영향을 알아보기 위해서 BER특성을 분석한 결과, 위상잡음에 따라 영향을 많이 받으며, 특히 고차원 변조방식을 가질수록 위상잡음에 더 영향을 많이 받음을 확인하였다. 모의실험결과 BER을 10$^{-5}$을 기준으로 했을 경우, QPSK 변조방식은 분산값에 따라서 대략 4dB, 16-QAM 변조방식은 대략 9dB 정도의 성능차이를 나타내었다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1711-1712
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• 2007

액체탱크의 레벨을 정밀측정하는 데 FMCW(Frequency Modulated Continuous Wave)를 이용하고자 한다. 우리는 1GHz 대역폭으로 Sweep하는 Frequency Source Module을 개발하여 테스트 중이다. 개발한 송수신 모듈은 주파수의 송수신을 위한 주요부품들로 구성되는데, VCO(Voltage Controlled Oscillator), 서큘레이터(Circulator), 필터(Filter), 전력분배기(Power Divider), PLL(Phase Locked Loop)제어부, 믹서, 증폭기 등이 그것이다. 이들 부품들이 위치한 RF Board와, 패치로 구성한 안테나를 이용하여 마이크로웨이브 신호를 송수신할 수 있으며, 송수신한 신호 간의 차주파수(beat frequency)성분을 측정하면 거리정보를 획득할 수 있다. 차주파수의 아날로그신호는 DSP를 이용하여 FFT를 수행하여 주파수 성분을 찾아 거리계산을 하도록 개발하였다. 거리 측정의 성능에 영향을 미치는 가장 큰 요소는 안정된 주파수를 만들어 낼 수 있느냐 하는 것이다. 본 논문에서는 제작한 VCO 모듈을 비롯한 개발 중인 각 모듈들을 소개하였다. 향후 VCO의 선형성 개선과, 난반사에 대한 Echo Cancel 알고리듬을 적용하여 제품의 상용화를 목표로 한다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.3
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• pp.413-419
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• 1987

In this paper, self-oscillating mixer is designed by small signal S-parameter and series feedback circuit. The input-output matching circuit is accomplished from double stub and additional matching stub. The self-oscillating mixer is oscillating itself and amplifies without any external local oscillator and an intermediate frequency amplifier, so it has advantages in its economical and system simplification. The experimental results show the maximum conversion gain 1.5d B and the noise figure 6.5d B at RF center frequency 4GHz and IF 1.1GHz` output oscillating power 4d Bm, efficiency 13.4%, stability -10MHz/V and -0.5MHz/\ulcornerC at oscillating frequency 5.1GHz.The rejection band loss characteristics in band pass filter and low pass filter are -40d B and -30d B, respectively.

• Journal of IKEEE
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• v.3 no.1 s.4
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• pp.79-85
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• 1999

In this paper, the resistive mixer for 5.86Hz wireless LAN, main part receiving system, was designed and implemented. The noise characteristics and the linearity in the base band was superior. For the use of local oscillator of mixer, dielectric resonator of stable output and temperature characteristics was designed. For the electrical tuning by the capacitance variation of varactor diode, the microstrip line and magnetic coupling characteristics of the dielectric resonance was used. It was obtained that gain of the proposed resistive mixer containing the RF cable loss, is -13.8dB, the conversion loss of frequency converter is -12 dB, and the output power of local oscillator is 1.67 dBm.