• Title/Summary/Keyword: Direct-Conversion

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Design of Programmable Baseband Filter for Direct Conversion (Direct Conversion 방식용 프로그래머블 Baseband 필터 설계)

  • Kim, Byoung-Wook;Shin, Sei-Ra;Choi, Seok-Woo
    • Journal of Korea Multimedia Society
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    • v.10 no.1
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    • pp.49-57
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    • 2007
  • Recently, CMOS RF integration has been widely explored in the wireless communication area to save cost, power, and chip area. The direct conversion architecture, rather than a more conventional super-het-erodyne, has been an attractive choice for single-chip integration because of its many advantages. However, the direct conversion architecture has several fundamental problems to solve in achieving performance comparable to a super-heterodyne counterpart. In this paper, we describe a programmable filter for mobile communication terminals using a direct conversion architecture. The proposed filter can be implemented with the active-RC filter and programmed to meet the requirements of different communication standards, including GSM, DECT and WCDMA. The filter can be tuned to select a detail frequency by changing the gate voltage of the MOS resistors. The gain of the proposed architecture can be programmed from 27dB to 72dB using the filter gain and VGA in 3dB steps.

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A Study on a Performance Analysis of Direct-Conversion Receiver In Additive White Gaussian Noise Channel (AWGN 채널환경에서 Direct-Conversion 수신기의 성능분석에 관한 연구)

  • 조형래;김철성;박성진
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.4
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    • pp.668-675
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    • 2001
  • Recently, the performance of the commercial PCS(Personal Communication Service) system has been improved to the uppermost limit and ultimately the next generation mobile communication is to be realized by IMT-2000 (International Mobile Communication-2000) to provide multimedia services. Therefore, the new type receiving system is researched actively and one of the most important part in a receiver is direct conversion method. The direct conversion method is suitable for low power consumption, small size, MMIC, and low price, which is to be adopted to the next generation mobile communication systems. In this case, however, several problems occur due to DC-offset. The DC-offset suppresses amplification of the required signal because of the leakage signal of frequency synthesizer in the system. In this thesis, the removing method of DC-offset was considered. There are four removing techniques of DC-offset, which are AC-coupling, large capacitor, DC-feedback loop, and DC-free coding. Among these, the AC-coupling method is the most simplest method and the DC-feedback loop method has the best performance. Then, the performance of the AC-coupling method and DC-feedback loop method are evaluated by HP's ADS simulation tool. As a result, the AC-coupling method cannot be used to the digital communication systems due to data loss. On the other hand, it was confirmed that the DC-feedback loop method is suitable for the direct conversion receiver.

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Technology trends in direct conversion receivers

  • Lee, Sang-Gug;Vladimir Krizhanovskii
    • The Magazine of the IEIE
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    • v.29 no.9
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    • pp.48-67
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    • 2002
  • Basic introduction to direct conversion architecture was given in comparison with heterodyne one. Principal difficulties in implementation of direct conversion receiver were presented, current state of research in this field and classified, on the basis of extensive analysis of published materials.

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Performance of Direct-Conversion Receiver with AC-Coupling in DC-Offset interference environment (DC-Offset 간섭환경에서 AC-Coupling을 갖는 직접변환 수신기의 성능)

  • 성봉훈;송윤정;김영완;김내수;서종수
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.9-14
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    • 2002
  • Direct-conversion receiver(DCR) architecture has superior advantages in size, cost, and power over superheterodyne receiver architectures. However, the use of direct-conversion receiver architecture has been limited due to the direct-current offset noise. The ac coupling, which is used to overcome the direct-current offset noise, causes an inter-symbol interference(ISI), whose effects can be effectively mitigated using an equalizer. In this paper, the performance of a direct-conversion receiver with ac coupling in the presence of direct-current offset is analyzed via computer simulation. The simulation result shows that by using decision feedback equalizer with LMS(Least Mean Square) algorithm, signal-to-noise ratio loss of the direct-conversion receiver compared to the idea receiver can be reduced to less than 1㏈ for corner frequencies as large as 10% of the symbol rate.

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RF Front-end Design of Direct Conversion Receiver using Six-Port (6-단자를 이용한 직접 변환 수신 전 처리부 설계)

  • Jang, Myoung-Shin;Yang, Woo-Jin;Oh, Dae-Ho;Kim, Young-Wan;Ko, Nam-Young
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.2
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    • pp.481-484
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    • 2005
  • The direct conversion method is classified into the structure using the mixing technology and six-port scheme. In the view point of complexity and integration the direct conversion method using the six-port scheme is superior to that with mixing technology. Expecially, the six-port direct conversion technology provides the low power consumption and the broad-band characteristic. In this paper, the six-port direct conversion receiver with the branch-line coupler and the ring hybrid coupler is designed respectively. The performances of the designed six-port schemes are analyzed and the six-port scheme with superior performance characteristics is proposed.

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RF Front-end Design of Direct Conversion Receiver using Six-Port (6-단자를 이용한 직접 변환 수신 전 처리부 설계)

  • Jang Myoung-shin;Kim Young-wan;Ko Nam-young
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.9 no.7
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    • pp.1534-1540
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    • 2005
  • The direct conversion method is classified into the structure using the mixing technology and six-port scheme. In the view point of complexity and integration the direct conversion method using the six-port scheme is superior to that with mixing technology. Expecially, the six-port direct conversion technology provides the low power consumption and the broad-band characteristic. In this paper, the six-port direct conversion receiver with the branch-line coupler and the ring hybrid coupler is desisted respectively. The performances of the designed six-port schemes are analyzed and the six-port scheme with superior performance characteristics is proposed.

Novel Heterogeneous Carbohydrase Reaction Systems for the Direct Conversion of Insoluble Carbohydrates: Reaction Characteristics and their Applications

  • Lee, Yong-Hyun;Park, Dong-Chan
    • Journal of Microbiology and Biotechnology
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    • v.9 no.1
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    • pp.1-8
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    • 1999
  • Most carbohydrates exist in nature in an insoluble state, which reduces their susceptibility towards various carbohydrases. Accordingly, they require intensive pretreatment for structural modification to enhance an enzyme reaction. The direct conversion of insoluble carbohydrates has distinct advantages for special types of reaction, especially exo-type carbohydrase; however, its application is limited due to structural constraints. This paper introduces two novel heterogeneous enzyme reaction systems for direct conversion of insoluble carbohydrates; one is an attrition coupled enzyme reaction system containing attrition-milling media for enhancing the enzyme reaction, and the other is a heterogeneous enzyme reaction system using extruded starch as an insoluble substrate. The direct conversion of typically insoluble carbohydrates, including cellulose, starch, and chitin with their corresponding carbohydrases, including cellulase, amylase, chitinase, and cyclodextrin glucanotransferase, was carried out using two proposed enzyme reaction systems. The conceptual features of the systems, their reaction characteristics and mechanism, and the industrial applications of the various carbohydrates are analyzed in this review.

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Design of K-Band CMOS Four-Port Direct Conversion Receiver for BPSK Demodulation (BPSK 복조를 위한 K-Band CMOS Four-Port 직접 변환 수신기 설계)

  • Moon, Seong-Mo;Park, Dong-Hoon;Yu, Jong-Won;Lee, Moon-Que
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.2
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    • pp.129-135
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    • 2010
  • In this paper, we propose and demonstrate a new four-port BPSK direct conversion receiver based on $0.18\;{\mu}m$ CMOS technology for K-band applications. The proposed direct conversion receiver is composed of two active combiners, an lumped LC balun, two power detectors and an analog decode. The designed direct conversion receiver is successfully demodulated BPSK signal with 40 Mbps in the K-band.

A Novel Compensation Scheme for I/Q Mismatch in an OFDM Direct-Conversion Architecture (OFDM 전송방식 기반의 Direct-Conversion 수신기에서 I/Q 불균형 보상을 위한 새로운 방법 제안)

  • Bae, Jung-Hwa;Park, Jin-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.12C
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    • pp.1265-1272
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    • 2006
  • This paper proposes a compensation method that can alleviate the problem of I/Q mismatch generated in the direct-conversion receiver of OFDM systems. In the proposed method, the amount of I/Q mismatch is estimated using null-carriers in transmitted signals, and it is subtracted from received symbols to suppress I/Q mismatch effects. Simulations show experiments that the proposed method can effectively eliminate the I/Q mismatch effects.

Direct Conversion receiver adapting DC offset free diode mixer (직접 변환수신기 (direct conversion receiver)에 적합한 DC offset이 없는 주파수 변환기를 채용한 직접변환 수신기의 설계)

  • 박필재;유현규;조한진
    • Proceedings of the IEEK Conference
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    • pp.361-364
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    • 2000
  • One of the problems using DCR(Direct Conversion Receiver) are DC offset, poor channel selectivity. APDP(Anti Parallel Diode Pair) can be good candidate for DCR frequency mixer due to its inherent End harmonic suppression. APDP shows good IP2 and DC suppression. This paper describe single APDP LO power characteristics, IP2, and receiver structure utilizing APDP frequency mixer

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