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Manos M. Tentzeris,Joy Laskar,Jong-Gwan Yook,Il Kwon Kim,Nickolas Kingsley,Matthew A. Morton,Stephane Pinel,John Papapolymerou 한국전자파학회JEES 2006 Journal of Electromagnetic Engineering and Science Vol.6 No.4
In this paper, the fractal shape is applied to microstrip band pass filters and integrated on a high-resistivity Si substrate to solve conventional 2<SUP>nd</SUP> harmonic problem. Conventional microstrip coupled line filters are popular in RF front ends, because they can be easily fabricated and integrated with other RF components. However, they typically have large second harmonics that can cause unwanted interference in interested frequency bands. Without any additional filters, the proposed Koch shape filters have suppressed the 2<SUP>nd</SUP> harmonics by about ?40㏈, so they can be used in systems such as direct conversion receiver with stringent harmonic suppression requirements.
A TWA Optical Receiver with Hybrid Integrated InP Detector
Hyeon Cheol Ki,Carl S.P. Chun,Joy Laskar,Nan Marie Jokerst,Martin A.Brooke,Yong-Sun Yoon,Jin Yeong Kang,Dong Sung Ma 한국정보과학회 1999 Journal of Electrical Engineering and Information Vol.4 No.6
To investigate the usefulness and feasibility of the TWA structure for low cost wide band system applications we designed a TWA optical receiver using low cost commercial process. The measured results show it is possible to achieve 18 ㎓ bandwidth with 7㏈ gain using low cost GaAs MESFET process with 20 ㎓ cut-off frequency. We also try, for the first time, the operation of an hybrid integrated OEIC using a fabricated TWA optical receiver and a thin film photo-detector 50㎛ in diameter. These results demonstrate that it is feasible to applicate TWA for the low cost wide band systems and to hybrid integrate wide band MMIC with thin film detectors for inexpensive high speed OEICs.
PA and LNA for millimeter-wave WPAN using 90 nm CMOS process
Kang, Min-Soo,Kim, Bong-Su,Byun, Woo-Jin,Kim, Kwang-Seon,Oh, Seung-Hyeub,Pinel, Stephane,Laskar, Joy,Song, Myung-Sun Wiley Subscription Services, Inc., A Wiley Company 2009 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.51 No.9
<P>We present the design and fabrication of power amplifier (PA) and low noise amplifier (LNA) in 60 GHz using 90 nm CMOS process. Both of them have three stages topology. We obtained small signal gain of 21 dB, P<SUB>1dB</SUB> of 4 dBm, and input/output return losses of <−9 dB in PA. We also obtained small signal gain of 25 dB, noise figure of <7 dB, P<SUB>1dB</SUB> of 1.5 dBm, input/out return losses of <−8 dB in LNA. The die sizes of PA and LNA are 1.1 × 0.8 mm<SUP>2</SUP> and 0.59 × 0.78 mm<SUP>2</SUP>, respectively. Both sizes contain the RF pads and bias pads. Especially, the size of LNA is reduced by using hairpin type matching structure. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2029–2032, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24549</P>
Spectrum Sensing Technologies for Cognitive Radio Based Interactive Broadcasting Services
Lim Kyu-Tae,Hur Young-Sik,Lee Jeong-Suk,Kim Ki-Hong,Lee Chang-Ho,Kim Hak-Sun,Laskar Joy The Korean Institute of Broadcast and Media Engine 2006 방송과 미디어 Vol.11 No.1
The Cognitive Radio (CR) technology is a promising solution for exploiting the limited spectrum resources and providing flexibility of spectrum usage. Future interactive broadcasting service can be realized by utilizing CR concept, since the up-link return channel can be found by the spectrum sensing method, which is core functional block of the CR system. In this paper, the spectrum sensing technologies of CR system is presented. First the system architecture of the CR with spectrum sensing block is presented. The suggested spectrum sensing technique consists of the coarse and the fine spectrum sensing. The coarse spectrum sensing technique adopted the wavelet transform to provide the multi-resolution sensing feature - Multi-Resolution Spectrum Sensing (MRSS). The fine spectrum sensing technique uses the beneficial properties of the autocorrelation function Analog Auto-Correlation (AAC). The simulation results for the proposed sensing technologies are presented for various incumbent signals.
Design and Analysis of CMOS T/R Switches With the Impedance Transformation Technique
Kim, Hyun-Woong,Ahn, Minsik,Lee, Ockgoo,Kim, Hyungwook,Yoon, Youngchang,Kim, Hyoungsoo,Lee, Chang-Ho,Laskar, Joy THE INSTITUTE OF ELECTRICAL ENGINEERS 2017 IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS Vol.27 No.12
<P>We present a 1.9-GHz high-power-handling complementary metal-oxide-semiconductor (CMOS) transmit/ receive (T/R) switch with the impedance transformation technique (ITT). The losses of the T/R switch, including matching networks, are analyzed, and the design method for the selection of an optimal switch operating impedance (RSW) is presented. The proposed T/R switch is implemented in a standard 0.18-mu m CMOS process. Experimental data show that the proposed design achieves more than 2 W of power-handling capability.</P>
LINC 시스템 구현을 위한 닫힌 해를 갖는 크기 위상 오차 검출 기법
명성식(Seong-Sik Myoung),이일규(Il-Kyoo Lee),임규태(Kyutae Lim),육종관(Jong-Gwan Yook),Joy Laskar 한국전자파학회 2008 한국전자파학회논문지 Vol.19 No.5
본 논문에서는 linear amplification with nonlinear components(LINC) 시스템의 두 신호 경로에 발생하는 크기와 위상 오차를 자동으로 검출하여 보상하는 알고리즘을 제안하였다. LINC 시스템은 첨두 대 평균 전력비가 큰 non-constant envelop 신호를 constant envelop 신호로 바꿔주어 고효율 전력 증폭기를 사용할 수 있는 장점이 있다. 그러나 LINC 시스템은 두 전력 증폭기의 경로에서 발생하는 매우 작은 경로 오차에 민감하게 성능이 열화된다는 단점이 있다. 본 논문에서는 4개의 테스트 신호를 이용하여 두 경로의 크기와 위상 오차를 검출하는 알고리즘을 제안하였다. 제안된 오차 검출 기법은 닫힌 해(closed form solution)를 가지며, 반복 계산이 필요하지 않아, 빠르고 효율적으로 오차를 검출할 수 있다. 본 논문에서는 제안된 기법을 적용하여 오차 검출과 검출된 결과를 반영하여 신호의 왜곡을 보상하는 digital-IF 형태를 갖는 LINC 시스템을 구현하였다. 구현된 LINC 시스템은 7 ㎒ 채널 대역을 갖고 16-QAM으로 변조된 IEEE 802.16 WiMAX 기저 대역 신호를 이용하여 성능을 분석하였으며, 제안된 기법을 이용하여 EVM이 -37.37 ㏈까지 개선되었으며, 이로서 LINC 시스템 구현시 제안된 오차 검출 및 보상 기법의 적용 타당성을 확인하였다. This paper proposed the path mismatch detection and compensation algorithm with closed form for linear amplification with non-linear components(LINC) system implementation. The LINC system has a merit of using the high efficient amplifier by transferring the non-constant envelop signal which is high peak to average signal ratio into constant envelop signal. However, the performance degradation is very sensitive to the path mismatch such as an amplitude mismatch and a phase mismatch. In order to improve the path mismatch, the error detection and compensation method is introduced by the use of four test signals. Since the presented method has the closed form solution, the efficient and fast detection is available. The digital-IF structure of LINC system applied by the proposed error detection and compensation algorithm was implemented. The performance was evaluated with the IEEE 802.16 WiMAX baseband sinal which has 7 ㎒ channel bandwidth and 16-QAM. The Error Vector Magnitude(EVM) of -37.37 ㏈ was obtained through performance test, which meets performance requirement of -24 ㏈ EVM. As a result, the introduced error detection and compensation method was verified to improve the LINC system performance.
MEMS 스위치 기반 재구성 고출력 증폭기를 갖는 재구성 능동 배열 안테나 시스템
명성식(Seong-Sik Myoung),엄순영(Soon Young Eom),전순익(Soon-Ik Jeon),육종관(Jong-Gwan Yook),Terence Wu,임규태(Kyu-Tae Lim),Joy Laskar 한국전자파학회 2010 한국전자파학회논문지 Vol.21 No.4
본 논문에서는 상용 초고주파 MEMS 스위치를 이용하여 세 개의 주파수 대역에서 재구성 동작이 가능한 주파수 재구성 능동 배열 안테나 시스템(Reconfigurable Active Array Antenna System: RAA System)을 제안하였다. MEMS 스위치는 삽입 손실 및 선형성 특성이 우수하고 격리도가 높아 주파수 재구성 시스템 구현 시, 재구성을 위한 스위치로 인한 성능 열화가 거의 없다는 장점이 있다. 제안된 주파수 재구성 능동 배열 안테나 시스템은 간단한 구조의 임피던스 매칭 회로(Reconfigurable impedance Matching Circuit: RMC)를 갖는 주파수 재구성 증폭기(Reconfigurable Front-end Amplifier: RFA)가 집적화 되어 있으며, 안테나 방사체(Reconfigurable Antenna Element: RAE)와 재구성 제어 보드(Reconfiguration Control Board: RCB)로 구성되어 있다. 본 논문에서 제안한 RAA 시스템은 850 ㎒, 1.9 ㎓, 3.4 ㎓의 세 개 주파수로 재구성되어 동작하며, 안테나 방사체는 2×2 배열을 가지고 각각의 방사체는 광대역 다이폴 형태를 갖는다. 제작된 RAA 시스템은 실험을 통하여 그 타당성을 확인하였다. In this paper, a novel frequency reconfigurable active array antenna(RAA) system, which can be reconfigurable for three reconfigurable frequency bands, is proposed by using commercial RF MEMS switches. The MEMS switch shows excellent insertion loss, linearity, as well as isolation. So, the system performance degradation of the reconfigurable system by using MEMS switches can be minimized. The proposed frequency reconfigurable active antenna system is consisted with the noble frequency reconfigurable front-end amplifiers(RFA) with the simple reconfigurable impedancematching circuits(RMC), reconfigurable antenna elements(RAE), as well as a reconfiguration control board(RCB) for MEMS switch control. The proposed RAA system can be reconfigurable for three frequency bands, 850 ㎒, 1.9 ㎓, and 3.4 ㎓, with 2×2 array of the RAE having broadband printed dipole antenna topology. The validity of the proposed RFA as well as RAA is also presented with the experimental results of the fabricated systems.