• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.9
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• pp.21-27
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• 1997

Square spiral inductors are designed with EM program in accordance with the inner diameter and the metal thickness which is 0.2.mu.m and 20.mu.m respectively. We propose a parameter extraction method based on the S-parameter. Lumped equivalent circuits of spiral inductors are analyed with reflection coefficient S$_{11}$, of witch freqency rnage is 1~10GHz. When metal thickness is 0.2.mu.m, S$_{11}$ with EM simulation is not the same as S$_{11}$ that of SPICE simulation. So we suggests a new lumped equivalent circuits which compensate circuits. Te new lumped equivalent circuits are adequate for other inductor with small scale at high frequencies.ncies.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.4
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• pp.274-280
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• 2007

This paper demonstrates an efficiency improvement of the class E power amplifier (PA) by tuning-out the input capacitance ($C_{IN}$) of the power HBT with a shunt inductance. In order to obtain high output power, the PA needs the large emitter size of a transistor. The larger the emitter size, the higher the parasitic capacitance. The parasitic $C_{IN}$ affects the distortion of the voltage signal at the base node and changes the duty cycle to decrease the PA's efficiency. Adopting the L-C resonance, we obtain a remarkable efficiency improvement of as much as 7%. This PA exhibits output power of 29 dBm and collector efficiency of 71% at 1.9 GHz.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.506-510
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• 2003

In this paper, a meander-line chip antenna with stacked layer is suggested, designed and fabricated employing the LTCC(Low Temperature Co-fired Ceramic) fabrication techniques. To reduce the antenna chip size, the meander-line antenna strip is distributed over three layer. Layers one interconnected using via holes. A 2.4 GHz chip antenna with size of $3.75{\times}7.9{\times}1.0 mm^3$ is designed and fabricated using the LTCC technique. Measurements of the fabricated antenna show 160 MHz bandwidth and 3.75 dBi maximum gain. The Measured reflection coefficient and radiation patterns agree well with the prediction by electromagnetic simulation.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.660-668
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• 2003

본 논문에서는 광대역 특성을 가지면서 소형화가 용이한 다중 미앤더 스트립 모노폴 안테나 구조를 제안하였다. 제안한 안테나 구조는 스트립으로 이루어진 수직한 모노폴 안테나를 미앤더 형태로 구부림으로써 안테나 높이를 감소시킬 수 있으며, 구부리는 회수가 증가할수록 대역폭이 늘어나는 특성을 갖는다. 제안한 다중 미앤더 스트립 모노폴 안테나 구조로부터 최근 주목을 받고 있는 UWB 롱신 대역폭을 포함하는 2.9 GHz에서 10.85 GHz까지의 넓은 대역폭과 전방향에 대한 최대/최소 복사이득의 차가 0.1 dBi 이내인 우수한 모노폴 안테나 복사패턴을 갖는 크기 $14 mm{\times}14 mm{\times}14mm$의 광대역/소형 안테나를 설계하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.9B
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• pp.1189-1195
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• 2001

본 연구에서는 수평면에 대해서 양방향성을 갖고 접지면을 향해서 주빔이 25$^{\circ}$의 기울기로 지향하도록 설계된 대칭 SSAIP(Strip, Air, Inverted Patch) 구조의 슬롯 결합 back-to-back 마이크로스트립 위생배열 안테나를 설계, 제작하였다. 이 구조의 안테나는 2-섹터 셀 사이트에서 기지국 또는 중계기의 지향성 안테나에 적용할 수 있으며, 도로 환경에 따라 지향각 25$^{\circ}$를 기준으로 약 $\pm$$10^{\circ}$정도 빔을 틸트할 수 있도록 위상기와 결합된다. 안테나는 공동모델을 이용하여 해석하고 앙상블로 설계한다. IMT-2000의 상.하향 링크 주파수 범위인 1.885~2.2GHz에서 안테나를 측정한 결과 임피던스 대역폭은 약 21%이였으며, $\pm$37$^{\circ}$의 지향각 오차를 보였다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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• pp.513-519
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• 1990

In order to realize an efficient and stable X-band harmonic generator, a 100 MHz frequency multiplier, an impulse generator using SRD(Step Recovery Diode) module, and a narrow-band bandpass waveguide filter have been designed and tested. By properly combining these devices an X-band harmonic generator has been realized. The output power of the harmonic generator was measured to be -1.5 dBm at 9 GHz which is the 90th harmonic of the 100MHz input. The power fluctuation of the harmonic generator due to temperature variation was observed to the about 0.15 dB during 24 hours of 4\ulcorner temperature variation.

• Journal of the Optical Society of Korea
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• v.18 no.2
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• pp.118-123
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• 2014

For multi parameter optimization of Raman Fiber Amplifier (RFA), a simple genetic algorithm is presented in the scenario of a 320 channel Dense Wavelength Division Multiplexed (DWDM) system at channel spacing of 25 GHz. The large average gain (> 22 dB) is observed from optimized RFA with the optimized parameters, such as 39.6 km of Raman length with counter-propagating pumps tuned to 205.5 THz and 211.9 THz at pump powers of 234.3 mW, 677.1 mW respectively. The gain flattening filter (GFF) has also been optimized to further reduce the gain ripple across the frequency range from 190 to 197.975 THz for broadband amplification.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.4
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• pp.247-255
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• 2011

This paper describes a CMOS outphasing transmitter using two wideband phase modulators. The proposed architecture can simplify the overall outphasing transmitter architecture using two-point phase modulation in phase-locked loop, which eliminates the necessity digital-to-analog converters, filters, and mixers. This architecture is verified with a WCDMA signal at 1.65 GHz. The prototype is fabricated in standard 130 nm CMOS technology. The measurement results satisfied the spectrum mask and 4.9% EVM performance.

• Journal of the Korean Ceramic Society
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• v.30 no.12
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• pp.1015-1022
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• 1993

The formation process of polycrystalline YIG(Y3Fe5O12) prepared by conventional method in Fe2O3-Y2O3 system was investigated. Effect of the microstructure of sintered body on electromagnetic properties was also investigated. Orthoferrite (YFeO3) was formed between 900 and 110$0^{\circ}C$. Formation of YIG phase begin at 110$0^{\circ}C$ with sharp increased saturation magnetization simultaneously. YIG phase is identified as single phase above 120$0^{\circ}C$. The microstructures and electromagnetic properties of sintered bodies are varied due to calcination condition of starting materials. The sintered YIG of calcined sample at 110$0^{\circ}C$ has such magnetic properties as Bs=1580G, BHC=1.89Oe, Tc=570K, ΔH(9.3GHz)=78Oe.

• Journal of the Korean Magnetics Society
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• v.2 no.2
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• pp.105-113
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• 1992

조성이 Mn$_{x}$Zn$_{1-x}$ Fe$_{2}$O$_{4}$ 훼라이트(x=0.75, 0.52)를 pusher type 연속 전기로를 이용하여 질소 분위기하에서 1360 .deg. C 로 3시간 동안 소결하여 얻어냈다. 본 연구에서는 스피넬 구조인 Mn-Zn 훼라이트의 FMR(Ferrimagnetic Resonance) 스펙트럼 특징과 초기투자율과의 상관성을 조사하고자 EPR X-band 스펙 트로미터를 이용 9.50 GHz의 microwave frequency에서 FMR 실험을 수행하였다. FMR 공명흡수선은 주 자기공명 흡 수선외에 낮은 자기장에서 약한 subsidiary 공명흡수선을 나타내는데 온도변화에 따른 주 자기공명 흡수선과 sub- sidiary 공명흡수선(제2, 제3 공명흡수선)의 세기, 공명선폭, g값 등의 온도 의존성을 연구함으로써 제2 공명흡수 선이 나타나는 원인을 분석하였으며, 자기공명 흡수선의 g값, 자기공명선 세기, 그리고 공명선폭과 초기투자율의 상관성을 연구하였다. 실험 결과 주 자기공명 흡수선의 g값, 자기공명선 세기, 공명선폭은 초기투자율 값과 밀접 한 관련이 있음을 확인할 수 있었다.었다.