• Title, Summary, Keyword: down-conversion

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Monolithic SiGe Up-/Down-Conversion Mixers with Active Baluns

  • Lee, Sang-Heung;Lee, Seung-Yun;Bae, Hyun-Cheol;Lee, Ja-Yol;Kim, Sang-Hoon;Kim, Bo-Woo;Kang, Jin-Yeong
    • ETRI Journal
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    • v.27 no.5
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    • pp.569-578
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    • 2005
  • The purpose of this paper is to describe the implementation of monolithically matching circuits, interface circuits, and RF core circuits to the same substrate. We designed and fabricated on-chip 1 to 6 GHz up-conversion and 1 to 8 GHz down-conversion mixers using a 0.8 mm SiGe hetero-junction bipolar transistor (HBT) process technology. To fabricate a SiGe HBT, we used a reduced pressure chemical vapor deposition (RPCVD) system to grow a base epitaxial layer, and we adopted local oxidation of silicon (LOCOS) isolation to separate the device terminals. An up-conversion mixer was implemented on-chip using an intermediate frequency (IF) matching circuit, local oscillator (LO)/radio frequency (RF) wideband matching circuits, LO/IF input balun circuits, and an RF output balun circuit. The measured results of the fabricated up-conversion mixer show a positive power conversion gain from 1 to 6 GHz and a bandwidth of about 4.5 GHz. Also, the down-conversion mixer was implemented on-chip using LO/RF wideband matching circuits, LO/RF input balun circuits, and an IF output balun circuit. The measured results of the fabricated down-conversion mixer show a positive power conversion gain from 1 to 8 GHz and a bandwidth of about 4.5 GHz.

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A 1.8GHz Low Voltage CMOS RF Down-Conversion Mixer (1.8GHz 대역의 저전압용 CMOS RF하향변환 믹서 설계)

  • 김희진;이순섭;김수원
    • Proceedings of the IEEK Conference
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    • pp.61-64
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    • 2000
  • This paper describes a RF Down-Conversion Mixer for mobile communication systems. This circuit achieves low voltage operation and low power consumption by reducing stacked devices of conventional gilbert cell mixer. In order to reduce stacked devices, we use source-follower structure. The proposed RF Down-Conversion mixer operates up to 1.85GHz at 1.5V power supply with 0.25um CMOS technology and consumes 2.2mA.

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Transformerless Three-Level DC-DC Buck Converter with a High Step-Down Conversion Ratio

  • Zhang, Yun;Sun, Xing-Tao;Wang, Yi-Feng;Shao, Hong-Jun
    • Journal of Power Electronics
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    • v.13 no.1
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    • pp.70-76
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    • 2013
  • For high power high step-down dc-dc conversion applications, conventional three-level dc-dc converters are subject to extreme duty cycles or increased volume and cost due to the use of transformers. In this paper, a transformerless three-level dc-dc buck converter with a high step-down conversion ratio is proposed. The converter comprises two asymmetrical half bridges, which are of the neutral point clamped structures. Therefore, the output pulse voltage of the converter can be obtained in terms of the voltage difference between the two half bridges. In order to realize harmonious switching of the converter, a modulation strategy with capacitor voltages self balance is presented. According to the deduced output dc voltage function, transformerless operation without extreme duty cycles can be implemented. Experimental results from a 1kW prototype verify the validity of the proposed converter. It is suitable for ship electric power distribution systems.

The Embedded System Realization Based on the IDCT for the Moving Image Down Conversion (동영상 축소전환을 위한 IDCT기반 임베디드 시스템 구현)

  • 김영빈;강희조;윤호군;류광렬
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.136-139
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    • 2004
  • This thesis is realization of embedded system that of MPEG-2 down conversion using IDCT. A method for down conversion of MPEG compressed video is to perform low-pass filtering and sub-sampling after full decompression. However, this method is need large memory and high computational complexity. Recent research has been focussed on the down conversion in the DCT domain. But DCT method is reduced image qualify. The embedded system is require low complexity, and high speed algorithm. When applied to embedded system that down conversion method, DCT method is played average 29 frame per second, and better 25% than spatial-domain down conversion.

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Structure-related Characteristics of SiGe HBT and 2.4 GHz Down-conversion Mixer

  • Lee, Sang-Heung;Kim, Sang-Hoon;Lee, Ja-Yol;Bae, Hyun-Cheol;Lee, Seung-Yun;Kang, Jin-Yeong;Kim, Bo-Woo
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.6 no.2
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    • pp.114-118
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    • 2006
  • In this paper, the effect of base and collector structures on DC, small signal characteristics of SiGe HBTs fabricated by RPCVD was investigated. The structure of SiGe HBTs was designed into four types as follows: SiGe HBT structures which are standard, apply extrinsic-base SEG selective epitaxial growth (SEG), apply selective collector implantation (SCI), and apply both extrinsic-base SEG and SCI. We verified the devices could be applied to the fabrication of RFIC chip through a fully integrated 2.4 GHz down-conversion mixer.

Down-Conversion Effect Applied to GaAs p-i-n Single Junction Solar Cell

  • Park, Jun-Seo;Kim, Ji-Hun;Go, Hyeong-Deok;Lee, Gi-Yong;Kim, Jeong-Hyeok;Han, Il-Gi
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.694-694
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    • 2013
  • With the growing need of more effective energy harvesting, solar energy has been sought as one of the prominent candidates among the eco-friendly methods. Although many types of solar cells have been developed, the electronic conversion efficiency is limited by the material's physical properties: solar cells can only harvest solar energy from limited range in solar energy spectrum. To overcome this physical limit, we approached by using the down conversion effect, transforming the high energy photons to low energy photons, to the range the designated solar cell can convert to electronic energy. In our study, we have fabricated GaAs single junction solar cells and applied CdSe quantum dots for down-conversion. We examine the effects of such application on the solar cell efficiancy, fill-factor, JSC, VOC, etc.

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실리콘 박막 태양전지를 위한 CdSe계 양자점 광변환구조체

  • Sin, Myeong-Hun
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.135.2-135.2
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    • 2014
  • Photon conversion technology for thin film solar cells is reviewed. The high-energy photons which are hardly absorbed in solar cells can be transformed the low energy photon by the photon conversion process such as down conversion or down shift, which can improve the solar cell efficiency over the material limit. CdSe-based quantum dot materials commonly used in LED can be used as the photon conversion layer for Si thin film solar cells. The photon conversion structure of CdSe-based quantum dot for Si thin film solar cells will be presented and the pros and cons for the Si thin film solar cells integrated with the photon conversion layers will be discussed.

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Image-rejection down-conversion mixer for bluetooth application using CMOS (CMOS를 이용한 Bluetooth용 이미지 제거 하향 주파수 변환기 설계)

  • 김대연;이진택;오승민;이상국
    • Proceedings of the IEEK Conference
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    • pp.365-368
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    • 2000
  • This paper describes image-rejection down conversion mixer for bluetooth application using 0.35u CMOS process. the proposed architecture is composed of LO phase shifter, mixer core, IF buffer, and IF phase shifter. IF phase shifter is designed using polyphase fillet. Simulation results show conversion gain = l0㏈, input 1㏈ compression point = -15.7㏈m. input third-order intercept point(IIP3) = -4.4㏈m, and image-rejection ratio = 37.8㏈, respectively, at 3V supply voltage, and 15.7㎃ current.

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Cancellation method of Second Order Distortion and DC-Offset in Down-Conversion Mixer (무선 수신기용 Down-Conversion mixer의 2차 비선형성과 DC-Offset 제거 기법)

  • Jung, Jae-Hoon;Hwang, Bo-Hyun;Kim, Shin-Nyoung;Jeong, Chan-Young;Lee, Mi-Young;Yoo, Chang-Sik
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.43 no.10
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    • pp.97-103
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    • 2006
  • This paper presents the method of improving second order intermodulation distortion(IMD2) and dc-offset problems in down-conversion mixer. A simple analysis reveals the IMD2 and dc-offset can be eliminated by controlling the duty cycles of local oscillator(LO) inputs. A mixer with the proposed method has been simulated with a $0.13{\mu}m$ RF CMOS technology with 5% mismatch in the load resistance, the mixer shows 2.04dBm IIP2 and 22mnV input referred DC-offset. By controlling two duty cycles of LO inputs, IIP2 and DC-offset can be improved to 38.8dBm and $777{\mu}V$, respectively.

Improving Efficiencies of DSC by Down-conversion of LiGdF4:Eu (Eu이 도핑된 LiGdF4의 Down-conversion을 이용한 염료감응형 태양전지의 효율 향상)

  • 김현주;송재성;김상수
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.3
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    • pp.323-328
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    • 2004
  • Down-conversion of Eu$^{3+}$ doped LiGdF$_4$ (LGF) for increasing the cell efficiency on dye-sensitized Ti $O_2$ solar cells has been studied. The dye sensitized solar cell (DSC) consisting of mesoporous Ti $O_2$ electrode deposited on transparent substrate, an electrolyte containing I$^{[-10]}$ /I$_3$$^{[-10]}$ redox couple, and Pt counter electrode is a promising alternative to the inorganic solar cell. The structure of DSC is basically a sandwich type, viz., FTO glass/Ru-red dye-absorbed Ti $O_2$/iodine electrolyte/sputtered Pt/FTO glass. The cell without down converter had open circuit potential of approximately 0.66 Volt, the short circuit photocurrent density of 1.632 mA/$\textrm{cm}^2$, and fill factor of about 50 % at the excitation wavelength of 550 nm. In addition, 5.6 mW/$\textrm{cm}^2$ incident light intensity beam was used as a light source. From this result, the calculated monochromatic efficiency at the wavelength of 550 nm of this cell was about 9.62 %. The incident photon to current conversion efficiency (IPCE) of N3 used as a dye in this work is about 80 % at around 590 nm and 610 nm, which is the emission spectrum of Eu$^{3+}$ doped LGF, results in efficiency increasing of DSC.C.