• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.135-140
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• 2019

In this paper, a frequency split type broadband drive amplifier operating in the L, S and C bands was designed and fabricated. Transistor is difficult to efficiently use when the fractional bandwidth of the drive amplifier is more than 100%, In particular, the characteristics of the driving amplifier are important for operating the power amplifier in which the characteristics of the output power and the efficiency are sensitively changed according to the frequency band. A frequency split methods was applied to maximize the bandwidth of a drive amplifier and to divide the output of the drive amplifier into low band and high band so that the transistor of the power amplifier located at the rear of the drive amplifier can be efficiently used. The designed drive amplifier was fabricated in GaAs HBT technology and 9-layer SiP, and verified by the measurements. The fabricated drive amplifier shows a gain of more than 8 dB and an output power of more than 15 dBm in the operating frequency range.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.2
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• pp.250-254
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• 2003

A film bulk acoustic resonator (FBAR) device for 2 GHz radio frequency (RF) bandpass filter application is presented. This FBAR device consists of an aluminum nitride (AlN) film sandwiched between top(Al) and bottom(Au) electrodes and an acoustic multilayer reflector of a silicon dioxide/tungsten (SiO2/W). The A/N film deposited using a RF sputtering was observed to have small columnar grains with a strongly preferred orientation towards c axis. In addition to a high quality factor (4300), a large return loss of 37.19 dB was obtained.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1700-1706
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• 2016

To improve the number of simultaneous transmissions of machine-to-machine traffic in a spread spectrum ALOHA channel, we propose a new spreading technique called doubly truncated cyclic code shift keying (DTCCSK). By truncating the codeset of cyclic code shift keying, DTCCSK freely adjusts the spreading factor and the symbol length. As a result, DTCCSK exhibits both a high spectral efficiency of M-ary signaling and low implementation complexity of a direct sequence.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10C
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• pp.948-955
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• 2006

In this paper, we propose motion estimation and compensation using Low-Band-Shift(LBS) with Integer Lifting Shift property. To overcome shift-variant property on wavelet coefficients, the LBS was previously proposed. This method which is applied to reference frame in video coding technique has superior performance in terms of rate-distortion characteristic. However, this method needs more memory and computational complexity. For the enhancement of those disadvantages, we propose motion estimation using Low-Band-Shift with Integer Lifting. The Integer Lifting implementation gives us good efficiency of calculation and storage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6C
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• pp.609-614
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• 2003

In this paper, a new filter structure to improve frequency response characteristics in CIC(Cascaded Integrator-Comb) decimation filters is proposed. Conventional filters improve passband characteristics, but they make worse aliasing band characteristics. In this paper, we propose a new filter which is called IFOP(Interpolated Fourth-Order Polynomials). By using this proposed filter, passband droop and aliasing band attenuation are simultaneously improved. Since proposed filter needs only one multiplication, computation is not much. And overall linear phase characteristics are maintained since the proposed filter is also linear phase. Finally, implementation cost of the proposed filter is compared with those of conventional filters.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.34-55
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• 2008

Gbps급의 대용량 데이터를 무선으로 전송하기 위해 60 GHz대역의 연구가 활발히 진행되고 있다. 60 GHz 대역은 공기 중에서 약 16 dB/km의 손실 특성을 가지므로 10미터 이내의 단거리 무선 대용량 데이터 전송용에 적합하다. 따라서 Kiosk 및 이동 단말기 간 대용량 무선 데이터 통신을 위한 저전력 CMOS chip 기술 및 실내용 고화질 비디오 전송을 위한 억세스 포인트와 HDTV에 장착되기 위한 단일 집적 모듈에 관한 연구가 크게 대두되고 있다. 본 원고에서는 저전력 소모 V-band 신호 발생기를 비롯한 CMOS SoC에 대한 세계적인 추세와 동향을 살펴보고, LTCC를 이용한 단일 집적 송수신 모듈에 대해 기술하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.5
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• pp.349-359
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• 1986

This paper is the basic research to identify automatically signals that are less than the bandwidth of 200Hz in shortwave band between 3 to 7 MHz and rarely appear. In order to do so, first, we describe the Detection and Estimation method of testing for the presence of absence about OOK signals of odB degree in 100KHz bandwidth. In the course of Detection and Estimation, it has decided the presence of OOK modulation Signal in additive noise to about 77% using LOD and E-C and about 90% using pattern model method of correlation function.

• Information and Communications Magazine
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• v.24 no.8
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• pp.40-52
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• 2007

본고에서는 비/저활용(57-66GHz) 대역에 대한 새로운 주파수 자원을 개척하여 HDTV급 신호를 케이블 및 위성방송 셋톱박스, 게임콘솔, DVD플레이어, 캠코더 및 이동식 멀티미디어 장비와 무선으로 연결시키는 전송 기술 개발을 위하여 Intel, Philips, Motorola, IBM, SiBeam, Panasonic, Sony등 세계적인 기업들이 국제 표준화(IEEE802.15, ETSI/BRAN, ECMA International) 공동 협력 및 기술 개발 경쟁을 벌이고 있는 상황이다. 본 표준기술은 국내 기업이 세계 시장을 장악하고 있는 LCD, PDP 및 차세대 DVD플레이어 등에 적용될 Wireless HD-SDI(High Definition Serial Data Interface)/ DVI(Digital Visual Interface)와, 외장 하드 디스크, 메모리 등 외부 기억 장치와의 자원 공유에 사용될 Muti-Gbps급 Wireless LAN, Wireless PAN, Wireless SAN(System Area Network) 등에 적용될 무선 전송 기술이다. 비/저활용 $59{\sim}66GHz$ 대역에 대한 국제 표준화로 IEEE802.15.3c를 중심으로 활발히 일어나고 있는 표준기술과 표준화 동향을 살펴본다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.3
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• pp.282-288
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• 2014

Recently there have been much interest in the GPS antenna performance improvement. In this paper, we propose very small patch antenna for GPS band. The proposed antenna resonance frequency was adjusted using the ground plane and variable capacitor connected the frame. The fabricated antenna was used a FR4 substrate by considering the difficulty and economical efficiency. Antenna measurement results was obtained good characteristics of VSWR 1.2, the passive antenna gain -0.60 dBi, the active antenna gain of 29 dB in center frequency of 1575.42 MHz GPS band.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5827-5831
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• 2011

In this paper, 5Ghz microstrip patch antenna for wireless LAN is designed, fabricated, and measured. To obtain wide bandwidth and high gain, antenna parameters such as patch size(W, L), the length of the slot(C), and the slot width(D) are simulated by HFSS(High Frequency Structure Simulator). From these parameters optimized, the microstrip patch antenna is fabricated using FR-4 substrate. The measured results of the antenna are as follows: The center frequency of 5.2 GHz, insertion loss of -41.17dB, bandwidth of 258MHz, and VWSR of 1.1.