• Journal of Electrical Engineering and Technology
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• 제5권1호
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• pp.151-155
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• 2010

Reconfigurable radio technology is needed to reconstruct frequency and modem functionality, which can be different in various regions. In addition, it makes a single mobile handset capable of supporting various standards of wireless communication and thus plays a key role in mobile convergence. An MMIC VCO (voltage controlled oscillator) has been developed for high power and wide bandwidth where Clapp-Gouriet type oscillators are adapted for series feedback, and was fabricated based on 0.15um pHEMT of TRW. The MMIC VCO was connected to an aluminar substrate on the carrier for testing. This MMIC VCO module showed good performance in comparison to existing works. Furthermore, it can be potentially extended to reconfigure an MMIC VCO for wireless systems such as military applications and satellite communications.

• 전자통신동향분석
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• 제33권6호
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• pp.34-40
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• 2018

Traditionally, many researchers have conducted research on terahertz technology utilizing optical devices such as lasers. However, nanometer-scale electronic devices using silicon or III-V compound semiconductors have received significant attention regarding the development of a terahertz system owing to the rapid scaling down of devices. This enables an operating frequency of up to approximately 0.5 THz for silicon, and approximately 1 THz for III-V devices. This article reviews the recent trends of terahertz monolithic integrated circuits based on several electronic devices such as CMOS, SiGe BiCMOS, and InP HBT/HEMT, and a particular quantum device, an RTD.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2000년도 종합학술발표회 논문집 Vol.10 No.1
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• pp.225-228
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• 2000

In this paper, the design for a low noise amplifier with the EM simulation is presented. The ATF36077 pHEMT device is applied to design LNA for U-NII frequency band (5 GHz ～ 6 GHz). The matching networks have been designed by the only open ended stub in order to reduce parasitic effects generated from a via structure. Through EM simulator, the simulation result shows that the linear gain (@5.5 GHz) is over 10 dB, input return loss and output return loss (@ 5.5 GHz) are a below 10 dB respectively, and the 3rd order intercept point is about 17 dBm.

• 한국재료학회지
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• 제5권1호
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• pp.96-103
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• 1995

30KV 전자빔리소그래피 장치를 사용하여 PMMA 3000$\AA$/P(MMA/MAA) 6000$\AA$의 이중구조에서 foot width 0.1$\mu$m이하, head width 0.4$\mu$m의 T-gate를 형성하였다. PMMA/P(MMA/MAA)/GaAS 구조에 대한 Monte Carlo 시뮬레이션 결과, 산란반경 0.1$\mu$m에서 전방산란전자와 후방산란전자의 에너지 비는 19.5:1로 나타났다. 전자빔리소그래피 공정에 필요한 PMMA 및 P(MMA/MMA)의 열처리 조건, 설게 선폭에 대한 패턴감도를 구하였다. MIBK : IPA = 1 : 1 현상액에 대한 PMMA 및 P(MMA/MAA)의 감마값(gamma value)은 2.3이었다. 광 및 전자빔리소그래피 장치의 혼합사용(mix-and-match) 결과 층간정렬도 (alignment accuracy)는 0.1$\mu$m(3$\sigma$) 이하를 얻었다.

• ETRI Journal
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• 제35권3호
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• pp.378-385
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• 2013

An S-band multifunction chip with a simple interface for an active phased array base station antenna for next-generation mobile communications is designed and fabricated using commercial 0.5-${\mu}m$ GaAs pHEMT technology. To reduce the cost of the module assembly and to reduce the number of chip interfaces for a compact transmit/receive module, a digital serial-to-parallel converter and an active bias circuit are integrated into the designed chip. The chip can be controlled and driven using only five interfaces. With 6-bit phase shifting and 6-bit attenuation, it provides a wideband performance employing a shunt-feedback technique for amplifiers. With a compact size of 16 $mm^2$ ($4mm{\times}4mm$), the proposed chip exhibits a gain of 26 dB, a P1dB of 12 dBm, and a noise figure of 3.5 dB over a wide frequency range of 1.8 GHz to 3.2 GHz.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.261-264
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• 2005

This paper presents the design of a down-conversion mixer with built-in active balun integrated in a $0.25\;{\mu}m$ pHEMT process. The active balun consists of series-connected common-gate FET and common-source FET. The designed balun achieved broadband characteristics by optimizing gate-width and bias condition for the reduction in parasitic effect. From DC to more than 6GHz, the active balun shows the phase error of less than 3 degree and the gain error of less than 0.4 dB. A single-balanced down-conversion mixer with built-in broadband active balun has been designed with optimum width, load resistor and bias for conversion gain and without any matching component for broadband operating. The designed mixer whose size of including on-chip bias circuit is $1\;mm{\times}1\;mm$ shows the conversion gain of better than 7 dB from 2 GHz to 6 GHz and $P_{1dB}$ of -10 dBm at 5.8 GHz

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.235-238
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• 1996

An inverted double channel AIGaAs/lnGaAs/GaAs heterostructure grown by LP-MOCVD is demonstrated and discussed. Sheet carrier densities in excess of $4.5{\times}10^{12}cm^{-2}$ at 300K are obtained with a hall mobility of $5010cm^2/V{\cdot}s$. The proposed device with a $1.8{\times}200{\mu}m^2$ gate dimension reveals an extrinsic transconductance as high as 320 mS/mm and a saturation current density as high as 820 mA/mm at 300K. This is the highest current density ever reported for GaAs MODFET's with the same gate length. Significantly improvements on gate voltage swing (up to 3.5 V) and on reverse breakdown voltage (-10V) are demonstrated due to inverted structure.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.609-610
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• 2006

A 77GHz MMIC transceiver module consisting of a power amplifier, a low noise amplifier, a drive amplifier, a frequency doubler and a down-mixer has been developed for automotive forward-looking radar sensor. The MMIC chip set was fabricated using $0.15{\mu}m$ gate-length InGaAs/InAlAs/GaAs mHEMT process based on 4-inch substrate. The power amplifier demonstrated a measured small signal gain of over 20dB from $76{\sim}77GHz$ with 15.5dBm output power. The chip size is $2mm{\times}2mm$. The low noise amplifier achieved a gain of 20dB in a band between $76{\sim}77\;GHz$ with an output power of 10dBm. The chip size is $2.2mm{\times}2mm$. The driver amplifier exhibited a gain of 23dB over a $76{\sim}77\;GHz$ band with an output power of 13dBm. The chip size is $2.1mm{\times}2mm$. The frequency doubler achieved an output power of -16dBm at 76.5GHz with a conversion gain of -16dB for an input power of 10dBm and a 38.25GHz input frequency. The chip size is $1.2mm{\times}1.2mm$. The down-mixer demonstrated a measured conversion gain of over -9dB. The chip size is $1.3mm{\times}1.9mm$. The transceiver module achieved an output power of 10dBm in a band between $76{\sim}77GHz$ with a receiver P1dB of -28dBm. The module size is $8{\times}9.5{\times}2.4mm^3$. This MMIC transceiver module is suitable for the 77GHz automotive radar systems and related applications in W-band.

• 대한전자공학회논문지TC
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• 제44권11호
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• pp.48-53
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• 2007

본 논문에서는 branch line coupler와 ${\lambda}/4$ 전송라인을 이용한 94 GHz 발룬 회로를 설계하였고, 이를 이용하여 높은 LO-RF 격리도 특성을 갖는 W-밴드용 MIMIC 단일 평형 주파수 혼합기를 개발하였다. 혼합기는 $0.1\;{\mu}m$ InGaAs/InAlAs/GaAs Metamorphic HEMT 다이오드를 적용하였다. 혼합기에 사용된 MHEMT는 전류이득차단 주파수가 154 GHz, 최대공진 주파수 특성이 454 GHz의 특성을 나타내었다. 제작된 혼합기의 특성 측정 결과 LO 입력 전력이 8.6 dBm일 때 12.8 dB의 변환 손실 특성을 나타내었으며, 입력 및 출력 P1 dB는 각각 5 dBm, -8.9 dBm의 특성을 나타내었다. 또한 LO-RF 격리도 특성은 94 GHz에서 37.2 dB로 높은 격리도 특성을 나타내었다. 격리도 특성을 고려할 때, 본 논문에서 설계 및 제작된 W-밴드용 MIMIC 단일 평형 주파수 혼합기는 기존의 밀리미터파 대역 혼합기와 비교하여 높은 LO-RF 격리도 특성을 나타내었다.

• 한국전자파학회논문지
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• 제16권5호
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• pp.482-487
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• 2005

본 연구에서는 distributed amplifer를 구성하는 cascode 단위이득단의 공통게이트의 게이트 단자에 가변 커패시터를 연결함으로써 출력 저항 값을 조절하는 방법을 제안한다. Cascode 이득단은 공통 소스 이득단에 비해 높은 이득, 높은 출력저항, 부성저항을 제공하는 등 여러 장점이 있지만 설계시 사용한 트랜지스터 모델이 부정확하고 공정변수가 달라진다면 이득이 떨어지기 시작하는 band edge에서 발진할 위험이 있다. 그러므로 회로가 제작된 이후에도 발진을 막을 수 있는 조절회로가 필요하게 되는데, cascode단위 이득단의 공통 게이트 단자에 연결된 가변 커패시터가 그 역할을 할 수 있다. 제작한 distributed amplifier를 측정해본 결과 가변 커패시터를 조절함으로써 이득 특성을 변화시킬 수 있었으며, 이는 회로의 안정도를 보장할 수 있음을 알 수 있었다. 49GHz의 밴드폭내에서 이득은 $8.92\pm0.82 dB$이며, 군지연은 41GHz 이내에서 $\pm9.3 psec$ 범위 이내였다. 사용된 모든 transistor는 GaAs 기반의 $0.15{\mu}m$ 게이트 길이를 가지 는 p-HEMT이며, distributed amplifier는 총 4개의 이득단으로 구성되어 있다.