• Title/Summary/Keyword: HEMT

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A New Small-Signal Modeling Method of HEMT Using Weakly Pinched-Off Cold-HEMT (약하게 핀치오프된 Cold-HEMT를 이용한 새로운 HEMT 소신호 모델링 기법)

  • 전만영
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.4
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    • pp.743-749
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    • 2003
  • By biasing the gate of cold-HEMT with a voltage slightly lower than the pinch-off point, a new small-signal modeling method that is free from gate degradation problem and requires no additional DC measurement is proposed in this paper. The method has shown excellent agreement between modeled and measured S-parameters up to 62 GHz at 49 different normal operating bias points.

Extraction of Extrinsic Circuit Parameters of HEMT by Minimizing Residual Errors (잔차 오차 최소에 의한 HEMT의 외인성 파라미터 추출)

  • Jeon, Man-Young
    • The Journal of the Korea institute of electronic communication sciences
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    • v.9 no.8
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    • pp.853-859
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    • 2014
  • This study presents a technique for extracting all the extrinsic parameters of HEMTs by minimizing the residual errors between a pinch-off cold-FET's gate and drain pad de-embedded Z-parameters and its modeled Z-parameters calculated by the cold-FET's remaining parameters. The presented technique allows us to successfully extract the remaining extrinsic parameter values as well as the gate and drain pad capacitance value without the additional fabrications of the gate and drain dummy pad.

Analysis of Current-Voltage characteristics of AlGaN/GaN HEMTs with a Stair-Type Gate structure (계단형 게이트 구조를 이용한 AlGN/GaN HEMT의 전류-전압특성 분석)

  • Kim, Dong-Ho;Jung, Kang-Min;Kim, Tae-Geun
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.47 no.6
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    • pp.1-6
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    • 2010
  • We present simulation results on DC characteristics of AlGaN/GaN HEMT having stair-type gate electrodes, in comparison with those of the conventional single gate AlGaN/GaN HEMTs and field-plate enhanced AlGaN/GaN HEMTs. In order to reduce the internal electric field near the gate electrode of conventional HEMT and thereby to increase their DC characteristics, we applied three-layered stacking electrode schemes to the standard AlGaN/GaN HEMT structure. As a result, we found that the internal electric field was decreased by 70% at the same drain bias condition and the transconductance (gm) was improved by 11.4% for the proposed stair-type gate AlGaN/GaN HEMT, compared with those of the conventional single gate and field-plate enhanced AlGaN/GaN HEMTs.

A High Power 60 GHz Push-Push Oscillator Using Metamorphic HEMT Technology (Metamorphic HEMT를 이 용한 60 GHz 대역 고출력 Push-Push 발진기)

  • Lee Jong-Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.7
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    • pp.659-664
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    • 2006
  • This paper reports a high power 60 GHz push-push oscillator fabricated using $0.12{\mu}m$ metamorphic high electron-mobility transistors(mHEMTs). The devices with a $0.12{\mu}m$ gate-length exhibited good DC and RF characteristics such as a maximum drain current of 700 mA/mm, a peak gm of 660 mS/mm, an $f_T$ of 170 GHz, and an $f_{MAX}$ of more than 300 GHz. By combining two sub-oscillators having $6{\times}50{\mu}m$ periphery mHEMT, the push-push oscillator achieved a 6.3 dBm of output power at 59.5 GHz with more than - 35 dBc fundamental suppression. The phase noise of - 81.5 dBc/Hz at 1 MHz offset was measured. This is one of the highest output power obtained using mHEMT technology without buffer amplifier, and demonstrates the potential of mHEMT technology for cost effective millimeter-wave commercial applications.

Implementation and Problem Analysis of Phase Shifted dc-dc Full Bridge Converter with GaN HEMT (Cascode GaN HEMT를 적용한 위상 천이 dc-dc 컨버터의 구현 및 문제점 분석)

  • Joo, Dong-Myoung;Kim, Dong-Sik;Lee, Byoung-Kuk;Kim, Jong-Soo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.6
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    • pp.558-565
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    • 2015
  • Gallium nitride high-electron mobility transistor (GaN HEMT) is the strongest candidate for replacing Si MOSFET. Comparing the figure of merit (FOM) of GaN with the state-of-the-art super junction Si MOSFET, the FOM is much better because of the wide band gap characteristics and the heterojunction structure. Although GaN HEMT has many benefits for the power conversion system, the performance of the power conversion system with the GaN HEMT is sensitive because of its low threshold voltage ($V_{th}$) and even lower parasitic capacitance. This study examines the characteristics of a phase-shifted full-bridge dc-dc converter with cascode GaN HEMT. The problem of unoptimized dead time is analyzed on the basis of the output capacitance of GaN HEMT. In addition, the printed circuit board (PCB) layout consideration is analyzed to reduce the negative effects of parasitic inductance. A comparison of the experimental results is provided to validate the dead time and PCB layout analysis for a phase-shifted full-bridge dc-dc converter with cascode GaN HEMT.

Quantum Mechanical Calculation of Two-Dimensional Electron Gas Density in AlGaAs/GaAs/AlGaAs Double-Heterojunction HEMT Structures (AlGaAs/GaAs/AlGaAs 이중 이종집합 HEMT 구조에서의 2차원 전자개스 농도의 양자역학적 계산)

  • 윤경식;이정일;강광남
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.29A no.3
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    • pp.59-65
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    • 1992
  • In this paper, the Numerov method is applied to solve the Schroedinger equation for $Al_{0.3}Ga_{0.7}AS/GaAs/Al_{0.3}Ga_{0.7}As$ double-heterojunction HEMT structures. The 3 subband energy levels, corresponding wave functions, 2-dimensional electron gas density, and conduction band edge profile are calculated from a self-consistent iterative solution of the Schroedinger equation and the Poisson equation. In addition, 2-dimensional electron gas densities in a quantum well of double heterostructure are calculated as a function of applied gate voltage. The density in the double heterojunction quantum well is increased to about more than 90%, however, the transconductance of the double heterostructure HEMT is not improved compared to that of the single heterostructure HEMT. Thus, double-heterojunction structures are expected to be suitable to increase the current capability in a HEMT device or a power HEMT structure.

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A Study of Determination of the Basic Device Parameters of HEMT Modeling by Measured S-parameter (측정한 산란계수에 의한 HEMT Modeling 변수의 결정에 관한 연구)

  • Park, Soon-Tae;Son, Byung-Moon
    • Journal of the Institute of Electronics Engineers of Korea TE
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    • v.37 no.1
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    • pp.1-11
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    • 2000
  • An accurate technique to retrieve HEMT modeling parameters with measurements of S-parameters and DC characteristics of HEMT is proposed. The extrinsic series resistances among HEMT modeling parameters are determined by the FUKUI method using the measured DC characteristics. And other parameters are determined by the measured S-parameters by HP 8510C Network Analyzer with various values of DC bias. The transconductance retrieved from the measured S-parameters, however, shows only 0.078% error comparing with the measured gm values. Therefore, the S-parameters measured directly for an individual transistor should be used for an accurate determination of the model parameters. The procedure for the retrieval of the circuit modeling parameters redescribed in detail in this thesis.

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High-Electron-Mobility-Transistor(HEMT) and its applications (고속 전자 이동 트랜지스터(HEMT)와 그 응용)

  • 이관호;김종헌
    • Electrical & Electronic Materials
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    • v.9 no.10
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    • pp.1074-1080
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    • 1996
  • 본 고에서는 HEMT를 사용하여 제작할 수 있는 여러가지 초고주파 소자들에 대하여 간락하게 나마 알아보았다. 고속 전자 이동 트랜지스터의 전위 우물이 가진 특성으로 인한 2차원 전자 개스(2DEG)의 이동을 이용한 고속소자의 사용은 정보의 보다 빠른 전달을 가져다 주었고 현재의 데이터 처리요구에 부응하고 있다. 최근 선진국의 초고주파 기술동향으로 볼때 HEMT의 구조와 동작에 관한 연구가 활발히 이루어 지고 있는 실정이며 그에 따른 초고주파 집적회로의 주파수 동작영역이 계속 넓어지고 있다. 하지만 현재 우리나라의 초고주파수에 대한 관심은 실로 놀라울 만큼 급부상하고는 있다고는 하나 그 초고주파대역에 사용되는 소자는 거의 선진국으로부터 전량에 가까운 정도로 수입에 의존하고 있는 실정이다. HEMT는 FET에 대한 응용소자로서 개발의 여지가 충분한만큼 관심을 가질 필요가 있다. 실제로 HEMT가 상업적으로 많이 이용되고 있는 분야는 저잡음 특성이 강하기 때문에 저잡음 증폭기용 소자로 사용되고 있고 제작시에 도핑되는 층의 배열을 변형하거나 첨가하여 소자내의 2차원 전자개스 층을 확장하여 어둑 빠른 소자 개발도 현재 이루어지고 있는 실정이다. 점점 더 증가하는 초고속 통신 시스템의 요구와 초고주파와 밀리미터파의 이용은 고속전자이동 트랜지스터의 미래를 밝게 해줄것이다.

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Photoelectrochemical oxidation of AlGaN-GaN HEMT (AlGaN/GaN HEMT의 광화학적 산화)

  • Moon, S.H.;Hong, S.K.;Ahn, H.J.;Lee, J.S.;Shim, K.H.;Yang, J.W.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.131-132
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    • 2007
  • An AlGaN/GaN high electron mobility transistor(HEMT) was fabricated and the effect of photoelectrochemical oxidation of AlGaN/GaN surface was investigated. The oxidation of AlGaN surface was done in water at the bias of 10 V under the deep UV light illumination. The sheet resistance of the AlGaN/GaN structure was increased and gate leakage current of the HEMT was decreased by the oxidation. However, the transconductance of the HEMT was not degraded by the oxidation.

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A Study on HEMT Device Process (Part II. Ohmic Contact Resistance in GaAs/AlGaAs Hetero-Structure) (HEMT소자 공정 연구 (Part II. HEMT 구조에서의 Online 접촉저항))

  • 이종람;이재진;박성호;김진섭;마동성
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.10
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    • pp.1545-1553
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    • 1989
  • The ohmic contact behavior in HEMT structure was compared with that in MESFET one throughout the specific contact resistance and microstructural change in both structures. A Au-Ge-Ni based metallization scheme was used and the alloying temperature of the ohmic materials was changed from 330\ulcorner to 550\ulcorner. The alloying temperature to obtain the minimum specific contact resistance in HEMT structure was 60k higher than that in MESFET. The volume fraction of NiAs (Ge) in MESFET structure increases with alloying temperature and/or the alloying time, which makes the decrease of specific contact resistance at the initial stage of ohmic metallization. In contrast, the volume fraction of NiAs(Ge) in HEMT structure was not dependent upon the specific contact resistance, which implies that the ohmic contacts are dominantly formed by the Ge diffusion to 2-DEG(two dimensional electron gas) layer.

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