• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.52-57
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• 1995

An accurate and efficient single-integral semi-numerical model is developed and applied to analyse effects of localized electronic states in the mobility gap on the drain-current versus gale-voltage characteristics of hydrogenated amorphous field-effect transistors. It is shown that the low-density deep-gap states distributed in the midgap also sensitively and largely influence the device electronic performance as well as well as the large-density tail states distributed near the conduction band edge.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.379-382
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• 2002

GaAs has wide band gap, Therefore that malarial can used high Temperature application. in this paper explain to current-voltage characteristics of thermal effect. we experiment on thermal test of current-voltage characteristics and gate leakage current with real device. As a result, we propose a current-volatage characteristics model. that model base on gate leakage current, and gate leakage current influence gate source voltage.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.229-232
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• 2000

In this study, An active band grass filter for 2.14GHz have been designed with MMIC using negative resistance circuit. The negative resistance element was realized with a common-drain FET with series inductive feedback. The designed active filter showed an insertion loss of 0dB at 2.14GHz and a 3-dB bandwidth of 125MHz.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.365-372
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• 1999

The plane deformation and spatial seepage(PDSS) analysis was developed to consider 3D flow of excess pore water as well as plane deformation of ground. Here is newly developed an equivalent model for PDSS analysis, which was the purpose to reduce number of finite elements and to take the effects of smear and well resistance into consideration. As the result of PDSS analysis with applying the new model, it is showed that the settlement-tin e relationship by PDSS agrees well with those of Plane strain(PS) and axisymmetric analyses, irrespective of existence of untreated layer. And the excess pore pressure distribution by PDSS is relatively agreed with that of axisymmetric analysis, not with that of PS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.2
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• pp.178-185
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• 1996

In this paper, a theoretical analysis of a wide band distributed mixer using a dual-gate GaAs MESFET's(DGFET) is introduced. Based on low noise mixer mode(LNM) region modeling of DGFET, variation of g/sub m/ and conversion gain are presented versus bias. The distributed mixer is composed of drain and gate transmission line, m-derived image impedance matching circuits at each input and output port, and DGFET's. Through computer simulation, wide-band characteristics of designed distributed mixer are confirmed. And, it is certificated that LO/RF isolation between gate 1 and gate 2 is obtained more than 15dB.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.291-294
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• 1999

This paper presents a GaAs MESMET self oscillating mixer for high efficiency L-band frequency conversion with small chip area consumption. Main circuit topology is consist of cascoded two FET with resonating part. The circuit is designed as unstably nonlinear for limited frequency band. FET with drain shorted to source is used for frequency tuning element. Linear conversion gain of -18.83 ㏈ is achieved with 9mA and 4V consumption. Input 1㏈ compression point is more than 11㏈m. The chip area is 1.4$\times$1.4 mm.

• Smart Media Journal
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• v.4 no.2
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• pp.55-61
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• 2015

A bandwidth-enhanced ultra-wide band (UWB) CMOS balun-LNA is implemented as a part of a software defined radio (SDR) receiver which supports multi-band and multi-standard. The proposed balun-LNA is composed of a single-to-differential converter, a differential-to-single voltage summer with inductive shunt peaking, a negative feedback network, and a differential output buffer with composite common-drain (CD) and common-source (CS) amplifiers. By feeding the single-ended output of the voltage summer to the input of the LNA through a feedback network, a wideband balun-LNA exploiting negative feedback is implemented. By adopting a source follower-based inductive shunt peaking, the proposed balun-LNA achieves a wider gain bandwidth. Two LNA design examples are presented to demonstrate the usefulness of the proposed approach. The LNA I adopts the CS amplifier with a common gate common source (CGCS) balun load as the S-to-D converter for high gain and low noise figure (NF) and the LNA II uses the differential amplifier with the ac-grounded second input terminal as the S-to-D converter for high second-order input-referred intercept point (IIP2). The 3 dB gain bandwidth of the proposed balun-LNA (LNA I) is above 5 GHz and the NF is below 4 dB from 100 MHz to 5 GHz. An average power gain of 18 dB and an IIP3 of -8 ~ -2 dBm are obtained. In simulation, IIP2 of the LNA II is at least 5 dB higher than that of the LNA I with same power consumption.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.4
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• pp.484-491
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• 2008

In this paper, we design and fabricate the L-band high speed pulsed HPA using LDMOS FET. And we propose the high voltage and high speed switching circuit for LDMOS FET. The pulsed HPA using LDMOS FET is simpler than using GaAs FET because it has a high gain, high output power and sin81e voltage supply. LDMOS FET is suitable for pulsed HPA using switching method because it has $2{\sim}3$ times higher maximum drain-source voltage(65 V) than operating drain-source voltage($V_{ds}=26{\sim}28\;V$). As results of test, the output peak power is 100 W at 1.2 GHz, the rise/fall time of output RF pulse are 28.1 ns/26.6 ns at 2 us pulse width with 40 kHz PRF, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.290-298
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• 2018

Herein, an S-band internally-matched power amplifier that shows a power capability of 300 W in a Long Term Evolution(LTE) band 7 is designed and fabricated using a CGHV40320D GaN HEMT from Wolfspeed. Based on the nonlinear model, the optimum source and load impedance are extracted from the source-pull and load-pull simulations at the fundamental and harmonic frequencies, and the harmonic impedance tuning circuits are implemented inside a ceramic package. The internally matched power amplifier, which is fabricated using a thin-film substrate with a high relative permittivity of 40 and an RF35TC PCB substrate, is measured at the pulsed condition with a pulse period of 1 ms and a duty cycle of 10%. The measured results show a maximum output power of 257~323 W, a drain efficiency of 64~71%, and a power gain of 11.5~14.0 dB at 2.62~2.69 GHz. The LTE-based measurement shows a drain efficiency of 42~49% and an ACLR of less than -30 dBc(excluding 2.62 GHz) at an average power of 79 W.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.303.1-303.1
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• 2014

좋은 전기적 특성을 가지면서 소자의 크기를 줄이기에 용이한 Gate-all-around (GAA) twin Si nanowire field-effect transistors (TSNWFETs)의 연구가 많이 진행되고 있다. Switching 특성과 단채널 효과가 없는 TSNWFETs의 특성은 GAA 구조의 본질적인 특성이다. TSNWFETs는 기존의 single Si nanowire TSNWFETs와 bulk FET에 비하여 Drive current가 nanowire의 지름에 많은 영향을 받지 않는다. 그러나 TSNWFETs의 전체 on-current는 훨씬 작고 nanowire의 지름이 작아지면서 줄어들게 되면서 소자의 sensing speed와 sensing margin 특성의 악화를 가지고 온다. GAA TSNWFETs의 제작 및 전기적 실험에 대한 연구는 많이 진행되었으나, GAA TSNWFETs의 전기적 특성에 대한 이론적 연구는 매우 적다. 본 연구에서는 GAA TSNWFETs의 nanowire 크기에 따른 전기적 특성을 관찰하였다. GAA TSNWFETs와 bulk FET의 전기적 특성을 양자역학을 고려하여 3차원 TCAD 시뮬레이션을 툴을 이용하여 계산하였다. GAA TSNWFETs와 bulk FET의 전류-전압 특성 계산을 통해 on-current 크기, subthreshold swing, drain-induced barrier lowering (DIBL), gate-induced drain leakage를 보았다. 전류가 흐르는 경로와 전기적 특성의 물리적 의미에 대한 연구를 위해 TSNWFETs에서의 전류 밀도, conduction band edge, potential 특성을 분석하였다. 시뮬레이션 결과를 통해 Switching 특성, 단채널 효과에 대한 면역 특성, nanowire의 단면적에 따른 전류 흐름을 보았다. nanowire의 크기가 작아지면서 DIBL이 증가하고 문턱전압과 전체 on-current는 감소하면서 소자의 특성이 악화된다. 이러한 결과는 GAA TSNWFETs의 전기적 특성을 이해하고 좋은 소자 특성을 위한 구조를 연구하는데 많은 도움이 될 것이다.