• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.10B
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• pp.1353-1359
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• 2001

본 논문에서는 위상획득과정과 동기과정에서 trade-off 현상을 향상시킨 듀얼 위상 주파수 검출기를 제안하여 차지펌프 PLL을 설계하였다. 듀얼 위상 주파수 검출기는 상승에지에서 동작하는 POSITIVE 위상 주파수 검출기와 하강에지에서 동작하는 NEGATIVE 위상 주파수 검출기로 구성되어 있다. 제안한 차지펌프는 전류뺄셈회로를 이용하여 전류 부정합을 감소시켰으며, reference spurs와 전압제어발진기의 변동을 감소시킬 수 있도록 구현하였다. 제안한 차지펌프 PLL은 0.25$\mu\textrm{m}$ CMOS 공정을 사용하여 SPICE로 시뮬레이션 하였으며, 그 결과 1.6~1.85GHz의 넓은 동기범위를 나타내었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.599-602
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• 2006

본 논문에서는 변형된 QMSA에 전기력선이 제한되지 않도록 용량을 장하한 MSA를 제안 하였다. 안테나의 크기는 약 $30mm\times86.6mm\times1.575mm$의 크기를 갖는다. 안테나 특성은 듀얼밴드 설계에서 1.93GHz와 2.03GHz의 두 동작 주파수 동조를 수월하게 하였다. 듀얼밴드 동작을 얻기 위한 기술은 양측 평행 평판과 $\lambda/2$ 방사 폐치를 변화시킴으로서 조정할 수 있다. 또한 1.93GHz 와 2.03GHz의 동작 주파수에 대해 E면과 H면에서 시뮬레이션 된 방사 패턴은 비교 분석되었다. 이동 통신을 위한 설계 제작된 듀얼 밴드 안테나 이득은 약 11.394dBi 이고 이득 변화는 아래와 위 공진 주파수에 대해 1.0dBi 보다 작다.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.5
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• pp.31-35
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• 2011

In this paper, the miniaturized FM transmitter with dual-frequency is developed, and tested in the field. In this system two frequencies 88.1 MHz and 88.3 MHz is used. The transmitter is designed with 2.6 cm^3 system size, horizontal, vertical, height respectively. The operating voltage is 3.7 V and used the built-in storage battery in order to minimize. The system can use continuously during 7 hour with once charging. The channel separation ability is 40 dB. Consequently, this system is used conveniently with short distance information transmitter system at the industry field.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.8
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• pp.20-26
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• 2001

In this paper, the charge pump PLL using the dual PFD to improve the trade-off between acquisition behavior and locked behavior is proposed. This dual PFD consists of a positive edge triggered PFD and a negative edge triggered PFD. The proposed charge pump shows that it is possible to overcome the issue of the charge pump current imsmatch by the current subtraction circuit. Also, this charge pump can suppress reference spurs and disturbance of the VCO control voltage. The proposed charge pump PLL is simulated by SPICE using 0.25${\mu}m$ CMOS process parameters.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.82-87
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• 2008

This paper presents a new fast locking dual-slope phase-locked loop. The conventional dual-slope phase-locked loop consists of two charge pumps and two phase-frequency detectors. In this paper, the dual-slope phase-locked loop was achieved with a charge pump and a phase-frequency detector as adjusting a current of the charge pump according to the phase difference. The proposed circuit was verified by HSPICE simulation with a $0.35{\mu}m$ CMOS standard process parameter. The phase locking time of the proposed dual-slope phase-locked loop was $2.2{\mu}s$ and that of the single-slope phase-locke loop was $7{\mu}s$.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.489-492
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• 2006

We demonstrate a beat frequency-Switchable dual-mode external cavity laser hybrid integrated on planar lightwave circuit with an FP-LD and a sampled grating as external reflector. The dual-mode external avity laser was able to switch its beat frequency from 132GHz to 406GHz by changing LD current from 50mA to 55mA.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1604-1611
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• 2003

For dual­band operation, it can be done by loading two pair of slits in the equilateral­triangular patch, one embeded close to the side edges of the patch and the other inserted at the bottom edge of the patch. The frequency ratio of the two operating frequencies can be tuned by varing the positions and lengths of the inserted slots at the bottom edge of the patch. While the calculated frequency ratio of the antenna by Ensemble 5.0 is $1.66 ({f_10}=1.928GHz, {f_20}=3.2GHz)$, the measured one is 2.04 $({f_10}=1.6806 GHz, {f_20}=3.435 GHz)$. The error in the frequency ratio is due on the fabrication dimension and feeding position error as well as on the permittivity dispersion effect.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.9
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• pp.23-30
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• 2009

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.1
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• pp.39-45
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• 2008

In this parer a branch type inverted-F structure antenna with dual-band is proposed. The proposed antenna has a size of about $70mm{\times}35mm{\times}0.8mm$ with a total mobile phone PCB for support and patch of about $12mm{\times}8mm{\times}0.8mm$. This antenna is designed to operate of frequency 2.45GHz and 5.8GHz, Bandwidth at each other frequency is satisfied $83MHz{\sim}100MHz$ in frequencies. Also, The designed and fabricated dual-band antenna for 2.45GHz, 5.8GHz have a gain between 2.0dBi and -1.0dBi at all bands.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1C
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• pp.103-112
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• 2010

In this paper, we propose a coarse and fine frequency synchronization method which is suitable for the 3GPP(3rd Generation Partnership Project) LTE(Long Term Evolution) FDD(Frequency Division Duplexing) / TDD(Time Division Duplexing) dual mode system. In general, PSS(Primary Synchronization Signal) correlation based estimation method and CP(Cyclic Prefix) correlation based tracking loop are applied for coarse and fine frequency synchronization in 3GPP LTE OFDMA(Orthogonal Frequency Division Multiple Access) system, respectively. However, the conventional coarse frequency synchronization method has performance degradation caused by fading channel and squaring loss. Also, the conventional fine frequency synchronization method cannot guarantee stable operation in TDD mode because of signal power difference between uplink and downlink subframe. Therefore, in this paper, we propose enhanced coarse and fine frequency synchronization methods which can estimate more accurately in multi-path fading channel and high speed channel environments and has stable operation for TDD frame structure, respectively. By computer simulation, we show that the proposed methods outperform the conventional methods, and verify that the proposed frequency synchronization method can guarantee stable operation in 3GPP LTE FDD/TDD dual mode downlink receiver.