• Title/Summary/Keyword: RF/DC

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The Effects of DC Offset on the Performance of Direct-Conversion Mobile Receiver in WCDMA System (WCDMA 시스템 직접변환 단말기 수신기에서 DC 오프셋에 의한 성능영향)

  • 이일규
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.7
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    • pp.730-735
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    • 2004
  • This paper describes what brings about DC offset and the impact or the DC offset on the performance or direct-conversion mobile receiver in WCDMA system. The performance degradation of $E_{b}/N_{o}$ due to the DC offset is presented through simulation result. Direct-conversion RF Transceiver which has the function of DC offset control is implemented and then applied to the WCDMA test-bed for the performance evaluation. The receiver performance degradation of $E_{c}/I_{o}$ is evaluated and analyzed by varying DC offset value. The practical test showed the minimum requirement of DC offset value to meet system performance.

Surface morphology and electrical properties of ISZO films deposited by magnetron sputting (마그네트론 스퍼터링에 의해 증착한 ISZO 박막의 표면 형상 및 전기적 특성)

  • Lee, Dong-Yeop;Lee, Jeong-Rak;Kim, Do-Geun;Lee, Geon-Hwan;Song, Pung-Geun
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2007.04a
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    • pp.116-117
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    • 2007
  • In-Sn-Zn-O 박막을 2개의 케소드(DC, RF)를 이용해magnetron co-sputtering법으로 polycarbonate (PC)기판위에 성막하였다. ITO와 ZnO 타겟은 각각 DC와 RF power supply에 의해 스퍼터 되었다. ISZO 박막의 가장 낮은 비저항은 RF power 55W 일 때 얻을 수 있었고, 이것은 케리어 밀도의 증가에 의한 것이라 생각되어 진다.

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A Study on the Characteristics of Ti Films Deposited by a DC Magnetron Sputtering Assisted with RF Voltage (고주파 마그네트론 스퍼터장치로 증착한 Ti 박막의 특성에 관한 연구)

  • Bae, Chang-Hwan;Lee, Ju-Hee;Han, Chang-Suk
    • Journal of the Korean Society for Heat Treatment
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    • v.22 no.3
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    • pp.143-148
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    • 2009
  • We have fabricated Ti metal films on Cu wire substrates by using a RF magnetron sputtering method at different RF powers (0, 30 and 60 W) in a high vacuum, and we have investigated the thin film characteristics and resistivity. The ion bombardment effect is increased by the method to superimpose RF power to DC power applied to two poles of the base; thus, the thin film is deposited at sputtering gas pressures below 1 Pa. Moreover, the thin film formation of the multilayer structure becomes possible by gradually injecting the RF power, and the thin film quality is improved.

A Study on the Calibration of GaAs-based 0.1-$\mu\textrm{m}$ $\Gamma$-gate MHEMT DC/RF Characteristics for the Development and Fabrication of over-100-GHz Millimeter-wave HEMT devices (100GHz 이상의 밀리미터파 HEMT 소 제작 및 개발을 위한 GaAs기반 0.1$\mu\textrm{m}$ $\Gamma$-게이트MHEMT의 DC/RF 특성에 대한 calibration 연구)

  • 손명식;이복형;이진구
    • Proceedings of the IEEK Conference
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    • 2003.07b
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    • pp.751-754
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    • 2003
  • Metamorphic HEMTs (MHEMTs) have emerged as excellent challenges for the design and fabrication of high-speed HEMTs for millimeter-wave applications. Some of improvements result from improved mobility and larger conduction band discontinuity in the channel, leading to more efficient modulation doping, better confinement, and better device performance compared with pseudomorphic HEMTs. We have studied the calibration on the DC and RF characteristics of the MHEMT device using I $n_{0.53}$G $a_{0.47}$As/I $n_{0.52}$A1$_{0.48}$As modulation-doped heterostructure on the GaAs wafer. For the optimized device performance simulation, we calibrated the device performance of 0.1-${\mu}{\textrm}{m}$ $\Gamma$-gate MHEMT fabricated in our research center using the 2D ISE-DESSIS device simulator. With this calibrated parameter set, we have obtained very good reproducibility. The device simulation on the DC and RF characteristics exhibits good reproducibility for our 0.1-${\mu}{\textrm}{m}$ -gate MHEMT device compared with the measurements. We expect that our calibration result can help design over-100-GHz MHEMT devices for better device performance.ormance.

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5.8 GHz Microwave Wireless Power Transmission System Development and Transmission-Efficiency Measurement (5.8 GHz 마이크로파 무선전력전송 시스템 개발 및 전송효율측정)

  • Lee, Seong Hun;Son, Myung Sik
    • Journal of the Semiconductor & Display Technology
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    • v.13 no.4
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    • pp.59-63
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    • 2014
  • Previous studies have selected wireless power transmission system using 2.45 GHz of ISM band, but the researches for 5.8 GHz microwave wireless power transmission have been relatively rare. The 5.8 GHz has some advantages compared with 2.45 GHz. Those are smaller antenna and smaller integrated system for RFIC. In this paper, the 5.8 GHz wireless power transmission system was developed and transmission efficiency was measured according to the distance. A transmitter sent the amplified microwaves through an antenna amplified by a power amplifier of 1W for 5.8 GHz, and a receiver was converted to DC from RF through a RF-DC Converter. In the 1W 5.8GHz wireless power transmission system, the converted currents and voltages were measured to evaluate transmission efficiency at each distance where LED lights up to 1m. The RF-DC Converter is designed and fabricated by impedance matching using full-wave rectifier circuit. The transmission-efficiency of the system shows from 1.05% at 0cm to 0.095% at 100cm by distance.

Temperature Dependence of DC and RF characteristics of CMOS Devices (RF-CMOS소자의 온도에 따른 DC및 RF 특성)

  • Nam, Sang-Min;Lee, Byeong-Jin;Hong, Seong-Hui;Yu, Jong-Geun;Jeon, Seok-Hui;Gang, Hyeon-Gyu;Park, Jong-Tae
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.37 no.3
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    • pp.20-26
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    • 2000
  • In this work, the degradation of g$_{m}$ , f$_{T}$ and f$_{max}$ of RF-CMOS devices have been characterized at elevated temperature. Since MOS transistors in RF applications are usually in saturation region, a simple empirical model for temperature dependence of g$_{m}$ at any measurement bias has been suggested. Because f$_{T}$ and f$_{max}$ of CMOS devices are proportional to g$_{m}$, the temperature dependence of f$_{T}$ and f$_{max}$ could be obtained from the temperature dependence of g$_{m}$. It was found that the degradation of f$_{T}$ and f$_{max}$ at elevated temperature was due to the degradation of g$_{m}$. From the correlation between DC and RF performances of CMOS devices, we can predict the enhanced f$_{T}$ and f$_{max}$ performances at low temperature.

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The resistivity properties of tungsten nitride films deposited by RF sputtering (RF 스퍼터링 증착에 의한 질화 텅스텐 박막의 비저항 특성)

  • 이우선;정용호;이상일
    • Electrical & Electronic Materials
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    • v.8 no.2
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    • pp.196-203
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    • 1995
  • We presented Tungsten and Tungsten Nitride thin films deposited by RF and DC sputtering. It deposited at various conditions that determining the resistivity and sheet resistivity by stabilizing the basic theory. We investigated properties of the resistivity and sheet resistivity of these films under various conditions, temperature of substrate, flow rate of the argon gas and content of nitrogen from nitrogen-argon mixtures. As the temperature of substrate increased and the flow rate of the argon gas decreased, the resistivities of these films reduced by structural transformation. We found that these resistivities were depend on the temperature of substrate, flow rate and electric power. Very highly resistive tungsten films obtained at 10W RF power. On the contrary, we found that films deposited by DC sputtering, from which very lowly resistive tungsten films were obtained. Tungsten nitride thin films deposited by reactive DC sputtering and the resistivities of these films increased as the content of nitrogen gas increased from nitrogen-argon mixture. And also we found the results show very good agreement, compared with experimental data.

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TEM Analysis of Interfaces between Cr Film Sputtered with RE Bias and Photosensitive Polyimide (RE 바이어스 스퍼터링한 Cr 박막과 감광성 폴리이미드 사이의 계면 TEM 분석)

  • 조성수;김영호
    • Journal of the Microelectronics and Packaging Society
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    • v.10 no.2
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    • pp.39-47
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    • 2003
  • Cr thin films were deposited on photosensitive polyimide substrates by RF bias sputtering and DC sputtering and the interfaces between Cr thin film and polyimide were observed using TEM. When the polyimide surface was in-situ RF plasma cleaned at the RF power density of 0.13-2.12 $W/cm^2$, increasing of RF power density changed the morphology of polyimide surfaces from round dig to sharp shape, and surface roughness increased by anisotropic etching. The intermixed layer-like interfaces between Cr and polyimide were observed in the RF bias sputtered specimens. This interface seems to be formed due to the RF cleaning effect; the polyimide surface was RF plasma cleaned while RF power was increased to the setting point before Cr deposition.

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Variable Conversion Gain Mixer for Dual Mode Receiver (이중 모우드 수신기용 가변 변환이득 믹서)

  • Park, Hyun-Woo;Koo, Kyung-Heon
    • Journal of Advanced Navigation Technology
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    • v.10 no.2
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    • pp.138-144
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    • 2006
  • In this paper, dual mode FET mixer for WiBro and wireless LAN(WLAN) applications has been designed in the form of dual gate FET mixer by using the cascode structure of two single gate pHEMTs. The designed dual gate mixer has been optimized to have variable conversion gain for WiBro and WLAN applications in order to save dc power consumption. The LO to RF isolation of the designed mixer is more than 20dB from 2.3GHz to 2.5GHz band. With the LO power of 0dBm and RF power of -50dBm, the mixer shows 15dB conversion gain. When RF power increases from -50dBm to -20dBm, the conversion gain decreases to -2dB from 15dB with bias change. The variable conversion gain has several advantages. It can reduce the high dynamic range requirement of AGC burden at IF stage. Also, it can save the dc power dissipation of mixer up to 90%.

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Fabrication and Characterization of Buried Resistor for RF MCM-C (고주파 MCM-C용 내부저항의 제작 및 특성 평가)

  • Cho, H. M.;Lee, W. S.;Lim, W.;Yoo, C. S.;Kang, N. K.;Park, J. C.
    • Journal of the Microelectronics and Packaging Society
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    • v.7 no.1
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    • pp.1-5
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    • 2000
  • Co-fired resistors for high frequency MCM-C (Multi Chip Module-Cofired) were fabricated and measured their RF properties from DC to 6 GHz. LTCC (Low Temperature Co-fired Ceramics) substrates with 8 layers were used as the substrates. Resisters and electrodes were printed on the 7th layer and connected to the top layer by via holes. Deviation from DC resistance of the resistors was resulted from the resister pastes, resistor size, and via length. From the experimental results, the suitable equivalent circuit model was adopted with resistor, transmission line, capacitor, and inductor. The characteristic impedance $Z_{o}$ of the transmission line from the equivalent circuit can explain the RF behavior of the buried resistor according to the structural variation.

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