• 대한전자공학회논문지
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• 제12권6호
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• pp.9-13
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• 1975

indefinite admittance matrix 회로해석법을 써서 2개의 연산증폭기를 갖는 능동 RC여파기의 합성방법을 제시하였고, 이 방법에 의하여 중심각파수와 대역폭을 독립적으로 제어할 수 있는 대역통과 능동여파기를 실현하였다. 보현된 회로에 대한 주파수특성의 이론치와 실험치는 좋은 일치를 보였다. Employing indefinite admittance matrix analysis method, a novel synthesis procedure of general active-RC filters using 2 operational amplifiers has been shown in this paper. With this procedure, a stable active-RC bandpass filter hart been designed, which provides for independent adjustment of the uning and band-width control. The predicted and actual performance is in good agreement.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2000년도 종합학술발표회 논문집 Vol.10 No.1
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• pp.216-219
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• 2000

A Ka Band 3-stage MMIC (Monolithic Microwave Integrated Circuits) LNA(Low Noise Amplifiers) has been designed. The MMIC LNA consists of two single-ended type amplication stapes and one balanced type amplication stage to satisfy noise figure characteristics and high gain and amplitude linearity. The 0.15um pHEMT has been used to provide a ultra low noise figure and high gain amplification. Series and Shunt feedback circuits were inserted to ensure high stability over frequency range of DC to 80 GHz. The size of designed MMIC LNA is 3100mm ${\times}$ 2400um(7.44$\textrm{mm}^2$). The on wafer measured noise figure of the MMIC LNA is less than 2.0 dB over frequency range of 22 GHz to 30 GHz.

• 대한전자공학회논문지
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• 제18권6호
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• pp.38-43
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• 1981

본 논문에서는 4개의 연산증폭기와 저항을 사용하여 비반전 유한이득증폭기를 구성하고 이를 능동 RC여파기에 응용하였다. 연산증폭기 GB적의 영향이 3차까지 무시될 수 있도록 하여. 3개의 연산증폭기를 사용한 경우보다 사용주파수범위를 확장할 수 있었다. 또한 극점주파수 100KHz인 대역통과여파기에 응용한 경우 여파기의 동작이 안정하고 이득특성은 이론치와 비교하여 그 오차가 최대 2%이내 임을 실험으로 확인하였다.

• 한국광학회:학술대회논문집
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• 한국광학회 2009년도 창립 20주년기념 특별학술발표회
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• pp.343-344
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• 2009

Pump wavelength dependence of the gain spectra was investigated by simulating the model of single-pumped fiber optical parametric amplifiers (FOPAs). Conditions for the single-pumped FOPAs having broad bandwidths with relatively large gains were optimized and the gain bandwidth was found to be as large as 146.4 nm when signal power and pump power were 316 nW and 7 W, respectively.

• 전자공학회논문지C
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• 제35C권8호
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• pp.42-51
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• 1998

An 8th-order elliptic low-pass filter with cutoff frequency of 3.13kHz is presented. The design procedure is based on teh 1/s impedance transformation which is applied to a minimum capacitor LC ladder network.The tranformed network is implemented with resistors and high Q frequency-dependent negative resistors (FDNR's). The high Q FDNR is realized with two transadmittance amplifiers. Detailed SPICE simulations show that the iflter has pass-band ripple of 0.18dB, stop-band attenuation over 100dB, cutoff frequency of 3.13 khz, and cutoff frequency temperature coefficient of 8.5ppm/.deg. C at supply voltage of .+-.5V.

• 전자공학회논문지D
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• 제34D권3호
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• pp.25-33
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• 1997

In the design of microwave multi-stage amplifiers composed of N amplifier modules, the variation of performances of amplifier as various connection length between modules has been studied. In addition, the methods, equations and conditions for the maximum gain or the most flat gain are presented. The results of sensitivity analysis for the connection length showed that the small change in phase of input, output reflection coefficients(S$_{11}$, S$_{22}$) of module itself is the most important in determination of connection length for the most flat gain. Th egain flatness of 2-module amplifier of which connection length between modules had been determined by presented methods was the best one out of performances with various arbitrary connectio lengths.s.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.108-112
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• 2003

A feedforward amplifier, which is composed of several components, is an open loop system. Therefore, feedforward amplifiers are apt to deteriorate the performance according to the environmental changes even though the cancellation performance and the linearization bandwidth of feedforward systems are superior to other linearization methods. A control method is needed for maintaining the original performance of feedforward amplifiers or to keep the performance within a little error bounds. In this paper, an adaptive control method, which has a good convergence characteristic and is easy to implement, is suggested. The characteristics of the suggested control method compare with the characteristics of other control methods and the simulation results are presented.

• 전기의세계
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• 제31권5호
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• pp.383-390
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• 1982

The high power glass laser system was designed and constracted which consisted of a TEM$\_$00/ mode Q-switching oscillator, a pulse shaping, system, two-stage pre-amplifiers, five-stage main amplifiers, a Faraday rotator, and a uni-guide slit. The laser output of 3OGW with the pulsewidth of 2 nsec was obtained by performing the amplifiing experiment in this system. When the laser light with the pulsewidth of 10 nsec was amplified, the large factor of amplification was obtained in the beginning of pulse, but the factor of amplification decreased gradually in the later part of pulse. Therefore, the laser light which has short pulsewidth of-2nsec must be amplified in order to obtain the larger factor of amplification. When the laser beam from the high power glass laser system was irradiated to plasma, the reflected laser light from plasma which occured inevitably could be attenuated to the order of 10$\^$-4/ by using the Faraday rotator and the uni-guide slit.

• Journal of electromagnetic engineering and science
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• 제2권2호
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• pp.81-86
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• 2002

This paper presents the full wave analysis of microwave circuits with nonlinear device using the finite difference time domain method. The equivalent current source is used to model nonlinear device and all the electric field components at the nonlinear device are updated by FDTD algorithm. The currents and voltages of nonlinear device are calculated by the state equations and iteration method. To validate the proposed method, the S-parameters of NEC NE72089 MESFET in various conditions are analyzed and the results are compared with those of the ADS. The proposed method is applied to the analysis of a microwave amplifier, which includes NEC NE72089 MESFET. The analysis results obtained by the present method show good agreement with those of the ADS.

• 한국광학회지
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• 제8권6호
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• pp.471-475
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• 1997

본 논문에서는 에르븀 첨가 광섬유 증폭기를 이용하여 단일 채널을 증폭할 때의 이득 동특성(gain dynamics)과 다채널을 증폭할 때의 이득 동특성에 대해 논의하였다. 여러 개의 에르븀 첨가 광섬유 증폭기가 연결된 증폭기 체인에서 채널 수의 변화에 의해 입력 광파워가 변할 때의 출력 광파워의 과도 현상(power transients)을 측정하고, 이를 $\mu\textrm{s}$ 이하의 응답 시간을 갖는 펌프 광파워 조절 회로를 이용하여 억제하였다.