• 전자공학회논문지 IE
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• v.45 no.1
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• pp.38-43
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• 2008

This paper presents a new interference cancellation method to remove the oscillation due to feedback signal of RF relay. In this paper, we estimate the feedback signal using to LMS(Least Mean Square) algorithm and remove the interference through attenuation signal arbitrary corresponding to feedback signal. From the various performance analysis for various doppler effects, a proposed method prevents from oscillation using -30dB attenuation signal as a cancellation value of feedback signal.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.4
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• pp.715-720
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• 2012

This study presents a hybrid balanced voltage controlled oscillator (VCO) circuit which is suitable for low phase noise operation at sub-1V supply voltages. Half circuits of the proposed VCO use the varactor-integrated feedback capacitors in their respective circuit. The varactor-integrated feedback capacitors further increase the negative resistance of the equivalent tank thereby ensuring stable start-up of oscillation even at the sub-1V supply voltage. In addition, this work theoretically analyses the phenomenon of the increase of the negative resistance. Simulation results using a $0.18{\mu}m$ RF CMOS technology exhibit the phase noises of -122.4 to -125.5.8 dBc/Hz at 1 MHz offset from oscillation frequency of 4.87 GHz over the supply voltages of 0.6 through 0.9 V.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.7B
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• pp.891-894
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• 2001

본 논문에서는 능동 배열 안테나에서 RF 대신 중간주파수를 이용하여 빔 추적을 하는 방법이 연구되었다. 안테나의 각 배열은 전압제어 발진기, 위상추적기, 혼합기와 결합되어 있으며 혼합기는 안테나 상에서 직접 RF 신호를 직접 중간주파수 신호로 변환시킨다. 전압제어 발진기 입력은 위상추적기에 의하여 조절되며 배열 안테나의 주사범위는 위상추적기와 전압제어발진기에 의하여 결정되었다.

• Journal of Advanced Navigation Technology
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• v.12 no.2
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• pp.122-131
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• 2008

In this paper, an S-band oscillator of the low phase noise property using miniaturized microstrip hairpin shaped ring resonator has been designed and implemented. The TACONIC's RF-35 substrate has a dielectric constant ${\varepsilon}_r$=3.5 a thickness h=20mil a copper thickness t=17 um and loss tangent $tan{\delta}$=0.0025. The designed and implemented 2.45 GHz oscillator shows low phase performance of -100.5 dBc/Hz a 100kHz offset. Output power 20.9 dBm at center frequency 2.45 GHz and harmonic suppression -32 dBc. The circuit was implemented with hybrid technique. But can be fully compatible with the RFIC's, MIC and MMIC due to its entirely planar structure.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.29-37
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• 1997

CW나 pluse의 형태로 RF를 발진하는 고출력 전자파 발진기는 레이더 체계의 기본요소이다. 레이더 체계의 성공적인 운행을 위한 요건 중에 적합한 전자파 발진기의 선택과 개발을 무시할 수 없다. 이차세계대전을 전후로 활발히 개발되었던 전자파 발진기들 중에는 널리 알려진 Magnetron과 klystron 이 있고 TWT(traveling wave tube)도 그 후 널리 사용되는 발진기이다. 지난 반세기를 지나오며 성능 및 신뢰도 등에서 괄목할만한 발전을 이루었으며 밀리미터파대역의 고출력 발진을 위해 gyrotron 등이 지난 30년간 개발되었다. 현재는 성능, 크기(무게) 및 가격의 문제뿐 아니라 고정밀 영상을 위한 고주파 발진기의 개발이 추진되고 있다. 여기서는 현재 레이더에 쓰이고 있는 magnetron, klystron, TWT 및 gyrotron에 대한 간략한 배경, 원리 및 특성 등을 비교 설명하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.4
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• pp.787-792
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• 2004

This paper shows the design, fabrication and performance of oscillator appled to 5.5GHz RF module for local wireless communication system. Super low noise HJ FET of NE3210S01 is used to obtain a good phase noise Performance. The design Parameters for the optimum operating performance are simulated with ADS simulation. The measured out Power is 10 dBm at 5.5GHz, the second harmonic suppression -31 dBc, and the phase noise characteristics -98.83 dBc at 100kHz offset frequency, respectively. This implemented oscillator is available to local wireless Communication system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.96-100
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• 2004

This paper shows the design, fabrication and performance of oscillator appled to 5.5GHz RF module for local wireless communication system. Super low noise HJ FET of NE3210S01 is used to obtain a good phase noise Performance. The design Parameters for the optimum operating performance are simulated with ADS simulation. The measured out Power is 10 ㏈m at 5.5GHz, the second harmonic suppression -31 ㏈c, and the phase noise characteristics -98.83 ㏈c at 100KHz offset frequency, respectively. This implemented oscillator is available to local wireless Communication system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.2
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• pp.294-301
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• 2000

One of the most important design parameters in a microwave radio transmitting system is to reduce spurious response from the output spectrum of the transmitting system. A Local oscillator (LO) is seldom totally pure and at the least contain some LO harmonic signals. A LO or any oscillator is a transmitter if provided with a suitable radiator, conduction, or leakage path. Where mixer is employed in the output of the LO mixer generated spurs can be increased by RF amplifier. To reduce LO leakage, notch filter or band pass filter has been conventionally used. In this paper, the leakage reduction(LR) signal, which has the same magnitude and the opposite phase with respect to LO leakage signal, is added to the output of mixer of the wireless LAN system. The LO leakage is reduced by 30 dB more than the conventional methods do. The proposed method is potentially suitable for low-cost, reliable, and simple application of monolithic microwave integrated circuits (MMICs)

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.43-45
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• 2002

이동통신 무선망 설계 시에는 전파강도가 부족하여 발생하는 부분적인 음영지역을 해결하기 위해서 기지국 신호를 재증폭하는 중계기를 이용하게 된다. 이러한 중계기는 입출력 안테나 사이에 충분한 격리도를 확보하지 않으면 증폭된 출력신호가 입력단으로 유입되어 시스템 발진현상이 발생하게 된다. 격리도에 따라 신호의 신호대잡음비를 저하시키는 수준의 미세발진이 발생하거나 출력증폭기의 한계점에 도달시키는 완전발진이 발생 된다. 기지국에 입력된 신호를 복조하여 신호의 상태에 따라 단말기 출력을 증가시키도록 제어하는 상황에서 이러한 중계기의 발진현상은 시스템 성능의 현저한 저하를 가져오게 된다. 본 논문에서는 실험적으로 발견된 중계기 발진현상을 수학적 모델링을 통하여 중계기의 특성 및 입출력 안테나 사이의 격리도와 미세발진현상과의 관계를 규명한다. 아울러 실험결과와의 비교분석을 통하여 본 논문에서 제시한 모델링의 타당성을 증명한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.1009-1014
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• 2012

This paper has proposed a 2,500 MHz ~ 2,570 MHz 0.13-${\mu}m$ CMOS RF front-end transmitter for LTE-Advanced systems. The proposed RF front-end transmitter is composed of a quadrature up-conversion mixer and a driver amplifier. The measurement results show the maximum output power level is +6 dBm and the suppression ratio for the image sideband and LO leakage are better than -40 dBc respectively. The fabricated chip consumes 36 mA from a 1.2 V supply voltage.