• 대한전자공학회논문지SD
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• 제38권6호
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• pp.383-389
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• 2001

본 논문에서는 밀리미터파 대역에서 응용 가능한 AIGaAs/InGaAs PHEMT를 제작하고 특성을 분석하였다. 제작에 사용된 PHEMT 웨이퍼는 ATLAS 시뮬레이터를 이용하여 DC 및 RF 특성을 최적화 하였다. 게이트 길이가 0.35 ㎛이고 서로 다른 게이트 폭과 게이트 핑거 수를 갖는 PHEMT를 전자빔 노광장치를 이용하여 제작하였다. 제작된 소자의 게이트 길이와 핑거수에 따른 RF 특성변화를 측정 분석하였다. 게이트 핑거 수가 2개인 PHEMT의 DC 특성으로 1.2 V의 무릎 전압, -1.5 V의 핀치-오프 전압, 275 ㎃/㎜의 드레인 전류 밀도 및 260.17 ㎳/㎜의 최대 전달컨덕턴스를 얻었다. 또한 RF 특성으로 35 ㎓에서 3.6 ㏈의 S/sub 21/ 이득, 11.15 ㏈의 MAG와 약 45 ㎓의 전류 이득 차단 주파수 그리고 약 100 ㎓의 최대 공진주파수를 얻었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.405-406
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• 2016

A bidirectional secondary LLC resonant converter with auxiliary switches and an additional inductor is proposed to achieve the high gain characteristics of LLC resonant convertors. Auxiliary switches, an additional inductor and a resonant capacitor are connected in the high voltage secondary side of the proposed converter. The ac analysis and operating characteristics of bidirectional secondary LLC resonant converter are investigated. A 1kW prototype bidirectional secondary LLC resonant converter connected to the $400V_{DC}$ buses is designed and tested to confirm the validity and applicability of the proposed converter.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.158-162
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• 1995

We report rf and power characteristics of AlGaAs/GaAs Heterojunction Bipolar Transistor (HBTs) for X-band power applications. HBTs have been fabricated with polyimide a an interlayer dielectric. By characterizing the DC and RF characteristics we obtained the maximum current gain of 45, BV$\_$CEO/ of 10 V, fT of 30 GHz and f$\_$max/ of 17 GHz for device with 6x14$\mu\textrm{m}$$^2$emitter size. To extract accurate equivalent parameters, the De-embedded method was applied for extraction of parasitic parameters and the calculation of circuit equations for intrinsic parameters. Based on the Load-pull method, power characteristics was simulated and measured to get the maximum output power of the device.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.345-351
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• 2018

This paper analyzes a resonant inverter to generate plasma. The resonant inverter consists of a full bridge converter, resonant network and reactor to generate a magnetic field for plasma generation. A plasma load has very distinct characteristics compared to conventional loads. The characteristics of plasma load are analyzed through experimental results. This paper presents the study on the resonant network, which was performed in order to determine how to achieve a constant current gain. Another important contribution of this study is the analysis of drop-out phenomenon observed in plasma loads which is responsible for unpredictable shutdown of the plasma generator that requires stable operation. In addition, the design process for the resonant network of a plasma generator is proposed. The validity of this study is verified through simulations and experimental results.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1428-1435
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• 2019

The total ionizing dose (TID) and non ionizing energy loss (NIEL) effects of 100 MeV phosphorous ($P^{7+}$) and 80 MeV nitrogen ($N^{6+}$) ions on 200 GHz silicon-germanium heterojunction bipolar transistors (SiGe HBTs) were examined in the total dose range from 1 to 100 Mrad(Si). The in-situ I-V characteristics like Gummel characteristics, excess base current (${\Delta}I_B$), net oxide trapped charge ($N_{OX}$), current gain ($h_{FE}$), avalanche multiplication (M-1), neutral base recombination (NBR) and output characteristics ($I_C-V_{CE}$) were analysed before and after irradiation. The significant degradation in device parameters was observed after $100MeV\;P^{7+}$ and $80MeV\;N^{6+}$ ion irradiation. The $100MeV\;P^{7+}$ ions create more damage in the SiGe HBT structure and in turn degrade the electrical characteristics of SiGe HBTs more when compared to $80MeV\;N^{6+}$. The SiGe HBTs irradiated up to 100 Mrad of total dose were annealed from $50^{\circ}C$ to $400^{\circ}C$ in different steps for 30 min duration in order to study the recovery of electrical characteristics. The recovery factors (RFs) are employed to analyse the contribution of room temperature and isochronal annealing in total recovery.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1477-1478
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• 2011

Solution processed zinc tin oxide (ZTO) thin films were studied using a spin coating for the fabrication of thin film transistors and simple circuits. The solution processed thin film transistors (W/L = 100/10 ${\mu}m$) have the average saturation mobility of 1.9 $cm^2$/Vs, threshold voltage of 20 V, and subthreshold slope of 0.5 V/decade. The dc characteristics of an inverter with $W_{load}=100\;{\mu}m$ and $W_{drive}=10\;{\mu}m$, measured under votage supply of $V_{DD}$ = +50 V. The inverter beta ratio is 20 ($R=(W_{drived}/L_{drive})/(W_{load}/L_{load})=20$) and $gain_{max}$ is 2. The characteristics of an oscillator were measured under voltage supply of $V_{DD}$ = +60 V.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.189-192
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• 2001

We have studied fabrication processes that form asymmetric $\Gamma$-gate with a 0.1${\mu}{\textrm}{m}$ gate length in MMIC's(Monolithic Microwave Integrated Circuits). Asymmetric $\Gamma$-gate was fabricated using mixture of PMMA and MCB. Thus pseudomorphic high electron mobility transistor (PHEMT's) with 0.1${\mu}{\textrm}{m}$ gate length was fabricated via several steps such as mesa isolation, metalization, recess, passivation. PHEMT's has the -1.75 V of pinch-off voltage (Vp), 63 mA of drain saturation current(Idss and 363.6 mS/mm of maximum transconductance (Gm) in DC characteristics and current gain cut-off frequency of 106 GHz and maximum frequency of oscillation of 160 GHz in RF characteristics.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권1호
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• pp.84-93
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• 2001

An electromagnetic micro x-y stage for probe-based data storage (PDS) has been fabricated. The x-y stage consists of a silicon body inside which planar copper coils are embedded, a glass substrate bonded to the silicon body, and eight permanent magnets. The dimensions of flexures and copper coils were determined to yield $100{\;}\mu\textrm{m}$ in x and y directions under 50 mA of supplied current and to have 440 Hz of natural frequency. For the application to PDS devices, electromagnetic stage should have flat top surface for the prevention of its interference with multi-probe array, and have coils with low resistance for low power consumption. In order to satisfy these design criteria, conducting planar copper coils have been electroplated within silicon trenches which have high aspect ratio ($5{\;}\mu\textrm{m}$in width and $30{\;}\mu\textrm{m}$in depth). Silicon flexures with a height of $250{\;}\mu\textrm{m}$ were fabricated by using inductively coupled plasma reactive ion etching (ICP-RIE). The characteristics of a fabricated electromagnetic stage were measured by using laser doppler vibrometer (LDV) and dynamic signal analyzer (DSA). The DC gain was $0.16{\;}\mu\textrm{m}/mA$ and the maximum displacement was $42{\;}\mu\textrm{m}$ at a current of 180 mA. The measured natural frequency of the lowest mode was 325 Hz. Compared with the designed values, the lower natural frequency and DC gain of the fabricated device are due to the reverse-tapered ICP-RIE process and the incomplete assembly of the upper-sided permanent magnets for LDV measurements.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.2070-2078
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• 2014

In this work, the frequency response of gate-all-around (GAA) Ge/GaAs heterojunction tunneling field-effect transistor (TFET) with hetero-gate-dielectric (HGD) and pnpn channel doping profile has been analysed by technology computer-aided design (TCAD) device-circuit mixed-mode simulations, with comparison studies among ppn, pnpn, and HGD pnpn TFET devices. By recursive tracing of voltage transfer curves (VTCs) of a common-source (CS) amplifier based on the HGD pnpn TFET, the operation point (Q-point) was obtained at $V_{DS}=1V$, where the maximum available output swing was acquired without waveform distortion. The slope of VTC of the amplifier was 9.21 V/V (19.4 dB), which mainly resulted from the ponderable direct-current (DC) characteristics of HGD pnpn TFET. Along with the DC performances, frequency response with a small-signal voltage of 10 mV has been closely investigated in terms of voltage gain ($A_v$), unit-gain frequency ($f_{unity}$), and cut-off frequency ($f_T$). The Ge/GaAs HGD pnpn TFET demonstrated $A_v=19.4dB$, $f_{unity}=10THz$, $f_T=0.487$ THz and $f_{max}=18THz$.

• 한국항해항만학회지
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• 제26권2호
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• pp.215-220
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• 2002

본 논문에서는 DTV 중계기용 Temperature Independent Biasing을 이용한 100 watt급 단위 전력증폭기를 설계한 후, 제작하였다. $20^{\circ}C$에서 $100^{\circ}C$까지의 온도변화에 대하여 단위 전력증폭기의 DC 동작점은 능동 바이어스에 의해서 고정되며, 증폭기의 소모전류의 변화량이 0.6A 이하의 우수한 특성을 얻었다. 제작된 단위 전력증폭기는 12dB 이상의 이득, $\pm$0.5dB 이하의 이득 평탄도, DTV 중계 주파수범위(470-806 MHz)에 걸쳐 15dB 이하의 입.출력 반사손실을 나타내었다. 100 Watt 단위 전력증폭기는 출력 전력이 100 watt일 때 2MHz의 오프셋에서 32dBc 이상의 상호 변조 왜곡(IMD)을 나타내었다.