• 전자공학회논문지A
• /
• 제32A권3호
• /
• pp.118-123
• /
• 1995

We have successfully fabricated a super low noise pseudomorphic HEMT(PHEMT) device with AlGaAs/InGaAs/GaAs sturcture by using improved T-Gate which have increased a large gaet cross-sectional area about two times in comparision with those of conventional T-gate processes. The PHEMSTs with 0.15$\mu$m-long and 140$\mu$m-wide gates have eshibited a super low noise characteristics, the noise figure of 0.45dB with associated gain of 10.87dB at 12GHz. The cut-off rewuqncy of the device is 94gHz with a transconductance of 418mS/mm.

• 한국레이저가공학회지
• /
• 제8권3호
• /
• pp.5-10
• /
• 2005

[ $InxGa_{1-x}P/GaAs$ ] structures were grown by chemical beam epitaxy(CBE), Pure phosphine($PH_3$) gases were used as group V sources. for the group III sources, TEGa, TmIn were used. $InxGa_{1-x}P$ epilayer was grown on SI-GaAs substrate and has a 1-${\mu}m$ thick. We have investigated the characteristics of $InxGa_{1-x}P$ by the photoreflectance(PR) spectroscopy, The PR spectrum of $InxGa_{1-x}P$ shows third-derivative feature whose Peaks Provide energy gap. The energy gap of $InxGa_{1-x}P$ has deduced composition x. From temperature dependance of PR spectra, temperature coefficient is $dEg/dT=-3.773{\times}10^{-4}$ eV/K, and Varshni coefficients $\alpha$ and $\beta$ values obtained $4{\times}10^4$ eV/K and 267 K respectively. Also, interaction $\alpha$B was 19.4 meV using the Bose-Einstein temperature relation, and $\Theta$ value related the average phonon frequency were 101.4 K. In particular, shoulder peak related to defects observed in PR signal that measured in temperature 82 K.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 추계종합학술대회 논문집
• /
• pp.637-640
• /
• 1998

A 35 ㎓ GaAs MMIC power amplifier was designed using a monolithic technology with AlGaAs/InGaAs/GaAs power PM-HEMTs, rectangualr spiral inductors and Si3N4 MIM capacitors. The GaAs power MESFETs in the input and output stages have total gate widths of 120 um and 320 um, respectively. Total S21 gain of 10.82dB and S11 of -16.26 dB were obtained from the designed MMIC power amplifier at 35 ㎓. And the chip size of the MMIC amplifier was 1.4$\times$0.8 $\textrm{mm}^2$

• Journal of electromagnetic engineering and science
• /
• 제6권2호
• /
• pp.92-97
• /
• 2006

In this paper, a fully integrated Ku-band tripler differential MMIC voltage controlled oscillator(VCO), which consists of a differential VCO core and two triplers, is developed using high linearity InGaP/GaAs HBT technology. The VCO core generates an oscillation frequency of 3.583 GHz, an output power of 3.65 dBm, and a phase noise of -96.7 dBc/Hz at 100 kHz offset with a current consumption of 30 mA at a supply voltage of 2.9 V. The tripler shows excellent side band rejection of 23 dBc at 3 V and 12 mA. The tripler differential MMIC VCO produces an oscillation frequency of 10.75 GHz, an output power of -13 dBm and a phase noise of -89.35 dBc/Hz at 100 kHz offset.

• 전기전자학회논문지
• /
• 제23권1호
• /
• pp.181-187
• /
• 2019

In this paper, we demonstrated a power amplifier monolithic microwave integrated circuit (MMIC) for X-band radar applications. It utilizes commercial $0.25{\mu}m$ GaN-based high electron mobility transistor (HEMT) technology and delivers more than 20 W of output power. The developed GaN-based power amplifier MMIC has small signal gain of over 22 dB and saturated output power of over 43.3 dBm (21.38 W) in a pulse operation mode with pulse width of $200{\mu}s$ and duty cycle of 4% over the entire band of 9 to 10 GHz. The chip dimensions are $3.5mm{\times}2.3mm$, generating the output power density of $2.71W/mm^2$. Its power added efficiency (PAE) is 42.6-50.7% in the frequency bandwidth from 9 to 10 GHz. The developed GaN-based power amplifier MMIC is expected to be applied in a variety of X-band radar applications.

• 산업경영시스템학회지
• /
• 제22권53호
• /
• pp.37-44
• /
• 1999

The problem to be studied here is the minimization of the total travel distance and the number of vehicles used for delivering goods to customers. Vehicle routes must also satisfy a variety of constraints such as fixed vehicle capacity, allowed operating time. Genetic algorithm to solve the VRPTW with heterogeneous fleet is presented. The chromosome of the proposed GA in this study has the 3-dimension. We propose GA that has the cubic-chromosome for VRPTW with heterogeneous fleet. The newly suggested ‘Cubic-GA (or 3-D GA)’ in this paper means the 2-D GA with GLS(Genetic Local Search) algorithms and is quite flexible. To evaluate the performance of the algorithm, we apply it to the Solomon's VRPTW instances. It produces a set of good routes and the reasonable number of vehicles.

• 대한본초학회지
• /
• 제28권2호
• /
• pp.17-23
• /
• 2013

Objectives : To investigate the hepatoprotective effect of Gardeniae Fructus (Ga) and Glycine semen preparatum (Gl) aqueous extract against D-galactosamine (D-GalN, 300mg/kg body weight) was administered to the male Sprague Dawley (SD) rats. Materials and Methods : The study was carried out on male SD rats (age matched, weight $250{\pm}10$ g). Experimental groups (Exp) divided four : Normal group (Nor) was administered saline, Control (Con) group was only received D-GalN (300 mg/kg) intraperitoneally. Exp was orally administered Ga (200 mg/kg; Ga group), Gl (700 mg/kg; Gl group), and Chizadochi-Tang (200 mg/kg+700 mg/kg, GG group) after D-GalN treatment during 14 days (n=6). Results : D-GalN administration induced hepatotoxicity in rats which was manifested by increased levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) but decreased total cholesterol (HDL C) and triglyceride (TG). The serum TG concentrations were significantly increased ($^{\sharp}p$ <0.05) in the Ga group compared with Con. AST and ALP activities were significantly decreased ($^{\sharp}p$ <0.05) in the all experimental groups compared with Con. ALT activities were significantly decreased ($^{\sharp}p$ <0.05) in the Ga group compared with Con. LDH activities were significantly decreased ($^{\sharp}p$ <0.05) in the GG group compared with Con. On the light microscopic study, a number of vacuole were observed in the Con, but decreased in experimental groups. Conclusion : Ga aqueous extract and Chizadochi-Tang extract possesses hepatoprotective potential, thus validating its use in alleviating toxic effects of D-GalN.

• 대한전자공학회논문지
• /
• 제13권5호
• /
• pp.1-8
• /
• 1976

게이트의 길이가 2mm인 GaAb 금속반도체전계치과트랜지스터를 HP8545 자동회로망분석기에 의하여 주파수 1∼2GHz 사이에서 산란계수를 측정하였고, 산란계수의 도움으로 완전한 등가회로를 구현하였다. 본 논문에서는 50Ω의 높은 입출력 Impedance로 정합시키기 위하여 Microstrip을 사용하여 GaAs MESFET증폭기를 개발하였으며 전력이득이 8dB, 정재파비가 1.5보다 적은 결과를 얻었다. Microwave GaAs Metal Semiconductor Field effect Transistors (MESFET) with the gate-length of two micrometers are investigated. The scattering parameters of the transistors have been measured from 1GHz to 2GHz by Hp8545 Automatic network analyzer. From the measured data, an equivalent circuit is established which consists of an ntrinsic and. extrinsic transistor elements. In this paper, GaAb MESFET Amplifier is used in conjunction with conventional microstrip techniques to match into a 50 ohms high input/output impedances system. We found that Power gain is less than 8dB and VSWR is less than 1.5 in L-Band.

• 한국전자통신학회논문지
• /
• 제6권5호
• /
• pp.621-627
• /
• 2011

본 논문에서는 로드-풀을 이용하여 X-band에서 on-Wafer 상태의 GaN HEMT 소자에 대한 성능을 분석하고 분석한 결과를 바탕으로 최적의 임피던스 점을 분석하였다. 패키징 하기 전 on-Wafer 상태에 있는 반도체 소자의 최적의 임피던스 분석을 통해 소자 자체에서 최적의 성능을 내는 방안을 제안하였다. Gate length가 0.25um이고 Gate Width가 각각 400um, 800um인 소자에 대한 최적의 임피던스를 선정하여 성능을 분석한 결과, 400um는 $P_{sat}$=33.16dBm(2.06W), PAE=67.36%, Gain=15.16dBm의 성능을 가지며, 800um는 $P_{sat}$=35.9 dBm(3.9W), PAE=69.23%, Gain=14.87dB의 성능을 보였다.

• 전기전자학회논문지
• /
• 제23권2호
• /
• pp.425-430
• /
• 2019

본 논문에서는 게이트 길이가 $0.25{\mu}m$인 GaN HEMT 기술을 사용하여 개발된 X-대역 전력 증폭기의 특성을 기술한다. 개발된 X-대역 전력 증폭기는 9~10 GHz의 대역에서 22.7 dB 이상의 소신호 이득과 43.02 dBm(20.04 W) 이상의 포화 출력 전력을 가진다. 최대 포화 출력 전력은 9.5 GHz에서 43.84 dBm (24.21 W)이였다. 전력 부가 효율은 41.0~51.24%의 특성을 얻었으며 칩의 크기는 $3.7mm{\times}2.3mm$이다. 출력 전력 밀도는 $2.84W/mm^2$를 나타내었다. 개발된 GaN 전력 증폭기는 다양한 X-대역 레이더 응용에 적용 가능할 것으로 예상된다.