• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.3
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• pp.239-254
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• 1988

In this paper an exciter which performs modulation and amplification is composed of high power(30dBm) VCO(Voltage Controlled Oscillator) using push-pull circuit. Modulation is FSK using PLL(Phase Locked Loop). A single loop PLL synthesizer having sequency range of 42.5-100.5MHz, 25KHz channel spacing and switching time of 1msec converts down the exciter VCO frequency to 1.25MHz. This signal mixed with the FSK modulated signal coming in the phase detector of exciter. The acquisition time of exciter for frequency hoppng is less than 200usec, so the total acquisition time for transmission is less that 1.5msec. There is no need of additional power amplification because power amlifiction by high power VCO is high enough to communicate within near distance. The proposed frequency synthesizer is not complex so it is suitable for low cost slow frequency hopping spread spectrum communication.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.1
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• pp.25-30
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• 2014

In this paper, we have implemented an FMCW radar for a near distance measurement. In the structure of the FMCW radar, it is a key problem to solve the VCO nonlinearity. In this work, we have adopted a VCO nonlinearity compensation algorithm using the spectrum correlation of beat signals. The radar experimented in this work uses an X-band(9.55~10.25GHz) microwave signal, and realizes precision of 3% in the range of 30m. The prototype can be applied to the front surveillance radar such as in vehicle anti-collision and probing robot mission.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.847-853
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• 2007

In this paper, a novel push-push voltage-controlled oscillator(VCO) using microstrip square open loop resonator and tunable negative resistance is presented. The microstrip square open loop resonator has the large coupling coefficient value, which makes a high Q value, and has reduced phase noise of VCO. The VCO with 1.8V power supply has phase noise of $-124.67{\sim}-122.67dBc/Hz\;@\;100 kHz$ in the tuning range, $5.744{\sim}5.859 GHz$. The FOM of this VCO is $-202.83{\sim}-201dBc/Hz\;@\;100 kHz$ in the same tuning range. When it has been compared with single-ended VCO using microstrip square open loop resonator, and push-push oscillator using microstrip line resonator, the reduced phase noise has been -8.51dB, and -33.67dB, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.7
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• pp.729-736
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• 2011

In this paper, we propose a varactor-diodeless voltage-controlled oscillator operating at X-band, and verify the possibility of applying to a receiver for microwave radar signal detection applications. The proposed VCO is realized by only single RF BJT device as a varactor diode is substitued by a intrinsic collector-base PN-junction of the active device which is used to generate negative resistance. The fabricated VCO meets the specification of the receiver, which has a 11.20~11.75 GHz tuning bandwidth with respect to the tuning voltage, 1.0~7.0 V, output power of 9.0~12.0 dBm and linear frequency tuning performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.333-341
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• 2015

In this paper, a 0.5~4 GHz frequency synthesizer having good phase noise performance is proposed. Wideband output frequencies of the synthesizer were synthesized using DDS(Direct Digital Synthesizer) and analog direct frequency synthesis technology in order to obtain fast settling time. Also in order to get good phase noise performance, 2.4 GHz DDS clock was generated by VCO(Voltage Controlled Oscillator) which was locked by the 100 MHz reference oscillator using SPD(Sample Phase Detector). The phase noise performance of wideband frequency synthesizer was estimated and the results were compared with the measured ones. The measured phase noise of the frequency synthesizer was less then -121 dBc @ 100 kHz at 4 GHz.

• Journal of Electrical Engineering and information Science
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• v.2 no.6
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• pp.202-207
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• 1997

Design and fabrication issues for an L-band GaAs Monolithic Microwave Integrated Circuit(MMIC) Voltage Controlled Oscillator(VCO) as a component of Personal Communications Systems(PCS) Radio Frequency(RF) transceiver are discussed. An ion-implanted GaAs MESFET tailored toward low current and low noise with 0.5mm gate length and 300mm gate width has been used as an active device, while an FET with the drain shorted to the source has been used as the voltage variable capacitor. The principal design was based on a self-biased FET with capacitive feedback. A tuning range of 140MHz and 58MHz has been obtained by 3V change for a 600mm and a 300mm devices, respectively. The oscillator output power was 6.5dBm wth 14mA DC current supply at 3.6V. The phase noise without any buffer or PLL was 93dB/1Hz at 100KHz offset. Harmonic balance analysis was used for the non-linear simulation after a linear simulation. All layout induced parasitics were incorporated into the simulation with EEFET2 non-linear FET model. The fabricated circuits were measured using a coplanar-type probe for bare chips and test jigs with ceramic packages.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.301-306
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• 2005

In this paper, a gain-boosting charge pump(CP) and a latch type voltage controlled oscillato.(VCO) with voltage controlled resistor(VCR) were proposed. The gain-boosting CP achieves good .current matching of less than 11$mu$V voltage difference between 43$mu$V and 32$mu$V in its output range from 0.8V to 2.3V. The VCO with VCR shows good linear characteristics over the range from 1V to 3V. The fabricated VCO exhibits -108dBc/Hz phase noise at a 100kHz and is comparable to that of the integrated LC-tank oscillator. The phase locked loop(PLL) with new circuits was simulated in a 0.35$mu$m CMOS process and showed 150$mu$s locking time.

• 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 IKEEE
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• v.3 no.1 s.4
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• pp.39-49
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• 1999

This paper describes a 1 GHz, low-phase-noise CMOS fractional-N frequency synthesizer with an integrated LC VCO. The proposed frequency synthesizer, which uses a high-order delta-sigma modulator to suppress the fractional spurious tones at all multiples of the fractional frequency resolution offset, has 64 programmable frequency channels with frequency resolution of $f_ref/64$. The measured phase noise is as low as -110 dBc/Hz at a 200 KHz offset frequency from a carrier frequency of 980 MHz. The reference sideband spurs are -73.5 dBc. The prototype is implemented in a $0.5{\mu}m$ CMOS process with triple metal layers. The active chip area is about $4mm^2$ and the prototype consumes 43 mW, including the VCO buffer power consumption, from a 3.3 V supply voltage.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.10
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• pp.115-122
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• 1996

A 300MHz PLL including FVC (frequency to voltage converter) is designed and fabricated in 0.8$\mu$m CMOS process. In this design, a FVC and a 2nd - order passive filter are added to the conventional charge-pump PLL to improve the acquisition time. The dual-rijng VCO(voltage controlled oscillator) realized in this paper has a frequency range form 208 to 320MHz. Integrated circuits have been fully tested and analyzed in detail and it is proved that pull-in speed is enhanced with the use fo FVC. In VCO range from 230MHz to 310MHz, experimental results show that realized PLL exhibits 4 times faster pull-in speed than that of conventional PLL.