• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.4
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• pp.46-52
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• 2009

In this paper, a novel VCO (Voltage Controlled Oscillator) structure is proposed to achieve the characteristic of low phase noise and a wide frequency tuning range. The proposed scheme adopts an impedance transforming technique to change a series resonance into a parallel resonance for maximizing the susceptance slope parameter. The manufactured VCO shows a frequency tuning bandwidth of 600MHz from 10.1GHz to 10.7GHz with a tuning voltage varying from 0 to 9V, an excellent phase noise below -119dBc/Hz@1MHz offset. The harmonic suppression is measured above 28dB.

• Journal of information and communication convergence engineering
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• v.16 no.1
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• pp.12-16
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• 2018

In this work, a voltage controlled oscillator (VCO) monolithic microwave integrated circuit (MMIC) was demonstrated for 10-GHz band motion detecting sensors. The VCO MMIC was fabricated using a $2-{\mu}m$ InGap/GaAs HBT process, and the tuning of the oscillation frequency is achieved by changing the internal capacitance in the HBT, instead of using extra varactor diodes. The implemented VCO MMIC has a micro size of $500{\mu}m{\times}500{\mu}m$, and demonstrates the value of inserting the VCO into a single chip transceiver. The experimental results showed that the frequency tuning characteristic was above 30 MHz, with the excellent output flatness characteristic of ${\pm}0.2dBm$ over the tuning bandwidth. And, the VCO MMIC exhibited a phase noise characteristic of -92.64 dBc/Hz and -118.28 dBc/Hz at the 100 kHz and 1 MHz offset frequencies from the carrier, respectively. The measured values were consistent with the design values, and exhibited good performance.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.499-500
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• 2006

This paper presents a fast switching CMOS frequency synthesizer with a new coarse tuning method for PHS applications. To achieve the fast lock-time and the low phase noise performance, an efficient bandwidth control scheme is proposed. Charge pump up/down current mismatches are compensated with the current mismatch compensation block. Also, the proposed coarse tuning method selects the optimal tuning capacitances of the LC-VCO to optimize the phase noise and the lock-time. The measured lock-time is about $20{\mu}s$. This chip is fabricated with $0.25{\mu}m$ CMOS technology, and the die area is $0.7mm{\times}2.1mm$. The power consumption is 54mW at 2.7V supply voltage.

• ETRI Journal
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• v.28 no.4
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• pp.506-508
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• 2006

A frequency selective surface (FSS), whose unit cell consists of a ternary tree loop loaded with a modified tripole, is proposed to block multiple frequency bands. Target frequency bands correspond to Korean personal communication services, cellular mobile communication, and 2.4 GHz industrial, scientific, and medical bands. Through the adjustment of inter-element and inter-unit cell gaps, and adjustment of the length of elements, we present an FSS design method that makes the precise tuning of multiple resonance frequencies possible. Additionally, to verify the validity of our approach, simulation results obtained from a commercial software tool and experimental data are also presented.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.163-166
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• 1999

In this paper, frequency synthesizer that can be used in IMT-2000 was designed and fabricated using dual loop PLL(Phase Locked Loop). For improving phase noise characteristic Voltage Controlled Oscillator was fabricated using coaxial resonator and eliminated frequency divider using SPD as phase detector and increased open loop gain. Fabricated frequency synthesizer had 1.82㎓ center frequency, 160MHz tuning range and -119.73㏈c/Hz low phase noise characteristic.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3315-3325
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• 1994

To study the variation of charging efficiency in the engine intake, the method to change the natural frequency of intake system using the intake control valve was studied and it has been used in actual engine to increase the intake air. In this paper, the method of characteristics was used to analyze the non-steady state and compared with the experimental data of the 6-cylinder diesel engine showing the effectiveness of the method theoretically.

• Journal of Biomedical Engineering Research
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• v.8 no.2
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• pp.111-116
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• 1987

In this study, basilar membrane motions and neural tuning responses are analysed with I-dimensional equations for cochlear fluid mechanics and an active cochlear model. The results are as follows. (1) The differences between basilar membrane motions in an active cochlear model and in an passive cochlear model are explained. (2) The basilar membrane motion curves and the neur'at tuning curves which are in accordance with physiological measurements ave obtained. (3) It is proved that the active mechanism makes cochlear highly frequency sensitive.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.315-316
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• 2013

This paper presents a parameter tuning method of a LLC resonant converter for a wireless charging circuit. A switched-capacitor is used to change the resonant frequency of the resonant circuit. The simulation results verify that the efficiency of the power transfer can be improved by a duty control of the switched-capacitor for various values of the coupling coefficient.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.2
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• pp.87-93
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• 2010

This paper presents a low-power, wide tuning range VCO with automatic two-step negative-Gm calibration loop to compensate for the process, voltage and temperature variation. To cover the wide tuning range, digital automatic negative-Gm tuning loop and analog automatic amplitude calibration loop are used. Adaptive body biasing (ABB) technique is also adopted to minimize the power consumption by lowering the threshold voltage of transistors in the negative-Gm core. The power consumption is 2 mA to 6mA from a 1.2 V supply. The VCO tuning range is 2.65 GHz, from 2.35 GHz to 5 GHz. And the phase noise is -117 dBc/Hz at the 1 MHz offset when the center frequency is 3.2 GHz.

• ETRI Journal
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• v.27 no.1
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• pp.75-80
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• 2005

This paper addresses a fully-integrated low phase noise X-band oscillator fabricated using a carbon-doped InGaP heterojunction bipolar transistor (HBT) GaAs process with a cutoff frequency of 53.2 GHz and maximum oscillation frequency of 70 GHz. The oscillator circuit consists of a negative resistance generating circuit with a base inductor, a resonating emitter circuit with a microstrip line, and a buffering resistive collector circuit with a tuning diode. The oscillator exhibits 4.33 dBm output power and achieves -127.8 dBc/Hz phase noise at 100 kHz away from a 10.39 GHz oscillating frequency, which benchmarks the lowest reported phase noise achieved for a monolithic X-band oscillator. The oscillator draws a 36 mA current from a 6.19 V supply with 47.1 MHz of frequency tuning range using a 4 V change. It occupies a $0.8mm{\times}0.8mm$ die area.