• 한국전기전자재료학회논문지
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• 제25권12호
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• pp.979-983
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• 2012

We proposed the ZnO thin film for a SAW filter by PLD and RF sputtering method. ZnO thin films was pre-deposited on a sapphire substrate as a seed layer by PLD method and then deposited on seed layer by RF sputtering. The surface characteristics of ZnO thin film were investigated by XRD, SEM and AFM. The minimum surface roughness was 1.92 nm and FWHM of rocking curve was $0.92^{\circ}$. We demonstrated the SAW filter with bandwidth of approximately 0.97 MHz and the center frequency of 18.72 MHz using the proposed ZnO thin film.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.817-820
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• 1999

In this paper, we describes RF receiver module for IMT-2000 handset with 5MHz channel bandwidth. The fabricated RF receiver module consists of Low Noise Amplifier-, RF SAW filter, Down-converter, IF SAW filter, AGC and PLL Synthesizer. The NF and IIP3 of LNA is 0.8㏈, 3㏈m at 2.14㎓, conversion gain of downconverter is l0㏈, dynamic range of AGC is 80㏈, and phase noise of PLL is -100 ㏈m, at 100KHz. The receiver sensitivity is -110㏈m, adjacent channel selectivity is -48㏈m.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2000년도 종합학술발표회 논문집 Vol.10 No.1
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• pp.424-428
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• 2000

In this paper, a MIC(Microwave Integrated Circuit) bandpass filter for wireless LAN(local area network) band is designed using hairpin resonators. The coupling between the hairpin resonators in the filter can be implemented with Y-Tpye coupling or X-Tpye coupling instead of conventional coupling in order to reduce the filter size. The filter with miniaturized hairpin resonator using parallel coupling is smaller in size by 50% more than that of a general hairpin filter

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.710-713
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• 2004

The design, simulation, modeling and measurement of a low temperature co-fired ceramic (LTCC) RF switch module for GSM applications is presented in this paper. RF switch module is constructed using a Rx/Tx switching circuit and integrated low pass filter. The low pass filter function was designed to operate in th GSM band. Insertion and return loss of the low pass filter were designed less than 0.3 dB and better than 12.7 dB at 900 MHz. The RF switch module contained 10 embedded passives and 3 surface mount components integrated on $4.6{\times}4.8{\times}1.2$ nm, 6-layer multi-layer integrated circuit. The insertion loss of switch module was measured at 900 MHz was 11 dB.

• Journal of electromagnetic engineering and science
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• 제2권2호
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• pp.124-127
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• 2002

A RF tunable bandpass filter using dielectric resonators and varactor diodes is redesigned to improve the passband flatness. Since the tunable liters are generally of narrow bandwidth and the Q value of the varactor diode is usually very low, the passband flatness is strongly deteriorated by sizeable distortion loss. To remedy this problem, we construct modified Chebyshev type filter by use of network synthesis techniques. The key of modified Chebyshev type filter is the rearrangement of the passband poles to improve the passband flatness. To maintain the constant passband bandwidth, design techniques of input/output stage and coupling windows are also applied. Experimental results show that the passband flatness can be improved by purposed method without any additional RF amplitude equalizer.

• Transactions on Electrical and Electronic Materials
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• 제17권4호
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• pp.217-221
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• 2016

In this work, open and short stubs that were fabricated on the silicon substrate and for which the periodically arrayed grounded-strip structure (PAGS) was employed were studied along with their basic RF characteristics for an applicability regarding the RF-matching components. The PAGS-employing open and short stubs showed losses that are much lower than that of the conventional stub on the silicon substrate. Concretely, the Q values of the open and short stubs are 9 and 10.2, respectively, while the Q value of the conventional open stub is 2.5. With the use of the PAGS-employing open and short stubs, a highly miniaturized harmonic-rejection filter was also fabricated on the silicon substrate. The filter exhibited a comparatively sound harmonic-suppression characteristic at n × 13 GHz, and its size is 0.1 mm², which is only 7% of the size of the conventional filter on the silicon substrate.

• 한국통신학회논문지
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• 제35권5A호
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• pp.482-489
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• 2010

본 논문에서는 RF PPF(Poly Phase Filter)를 이용하는 이미지 제거회로에서 광대역의 모든 RF 신호를 한꺼번에 Quadrature 신호로 변환시키는 기존 구조와 다르게 광대역의 RF 신호를 여러 개의 협대역(Narrow band)으로 세분화시켜 Quadrature 신호로 변환시키는 새로운 구조의 주파수 가변형 협대역 DQ-IRM(Double-Quadrature Image Rejection Mixer) 구조를 제안하였다. 기저대역에서 선택한 채널과 그 인접 2-3개 채널이 포함된 협대역 RF 신호만을 선택적으로 Quadrature 신호로 변환시키는 이 구조는 RF PPF의 차수를 줄일 수 있기 때문에 낮은 경로손실 특성과 높은 이미지제거 성능을 동시에 구현이 가능하다. 제안한 DQ-IRM를 이용하여 지상파 디지털멀티미디어방송(Terrestrial Digital Multimedia Broadcasting, T-DMB) 수신용 CMOS RF 튜너 칩을 설계하고 그 성능을 검증하였다. 설계된 CMOS RF 튜너 칩은 CMOS 0.18 um 테크놀로지를 이용하였으며, 170-240 MHz 주파수대역에서 약 1.26 dB의 잡음특성과 약 51 dB 이상의 이미지제거 성능을 얻었다. 설계된 칩 사이즈는 $3.0{\times}1.8mm2$이며, 총 소모전력은 동작전압 1.8 V에서 55.8 mW이다.

• 한국항공우주학회지
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• 제40권4호
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• pp.292-299
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• 2012

칼만 필터를 이용하여 RF 탐색기의 시선각 변화율 추정을 수행하였다. 김발형 탐색기의 모델링을 기반으로 칼만필터를 설계하였다. 필터 설계 시 주요한 인자인 공정 잡음 및 측정 잡음의 특성에 대해 살펴보았으며, RF 탐색기의 신호 특성에 맞는 측정 잡음치를 선정하여 필터링을 수행하였다. 측정 잡음관리를 위해 SNR 및 관련 신호를 이용하였으며, 공정 잡음에 따른 필터의 민감도 확인을 위해 대수적 방식을 사용하였다. 일식 등으로 탐색기 신호가 없는 경우 선형 해석을 통해 필터의 안정도를 분석하였다. 수치 시뮬레이션을 통해 제안된 시선각 변화율 추정기법의 타당성을 검토하였다.

• 마이크로전자및패키징학회지
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• 제6권3호
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• pp.1-7
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• 1999

본 연구에서는 900MHz대역 수신기용으로 선행 개발되어진 RF 칩세트를 장착한 RF 특성평가 보드를 개발하였으며, 환경평가시험을 수행하였다. 선행 개발되어진 RF-IC 칩에는 저잡음증폭기, 하향변조 주파수혼합기, AGC Amp, SW-CAP 필터 등을 포함하고 있으며, 이에 따른 정합회로와 RF/IF SAW 필터, 듀플렉서 필터 및 전원공급회로를 RF 특성평가보드에 첨가하여 제작하였다. 공급전원은 2.7에서 3.6V이며, RF 보드의 소모전류는 42mA로 나타났으며, 동작 주파수는 RF 입력이 925~960MHz으로 제작, 측정되었다. 측정결과 일반적인 900MHz용 디지털 이동통신단말기의 RF 수신특성과 유사하게 양호한 결과를 보였다.

• ETRI Journal
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• 제37권6호
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• pp.1077-1086
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• 2015

This paper presents a general-purpose design scheme of a filter bank (FB)-based radio frequency (RF) transceiver that operates across the entire ultra-high frequency (UHF) TV band from 470 MHz to 698 MHz and complies with the TV white space (TVWS) regulatory requirements. To this end, an intermediate frequency (IF) band-pass filter (BPF) with a sharp skirt characteristic is considered as a solution for handling the incoming signals from a baseband modem. Specifically, an FB-based BPF structure with four ceramic resonator filters that effectively rejects unwanted signals is proposed to extract a desired signal in the TV band. Achievable data rates of a cognitive radio system (CRS) employing the proposed FB-based RF transceiver at the application layer are investigated in both wired and wireless environments. The service coverage of the CRS network is measured according to several modulation and coding schemes (MCSs) of the CRS. The results show that the coverage of a wireless network in a nearly open area can be extended by more than 9.3 km in the TVWS. Experimental results also confirm that the proposed FB-based RF transceiver is adequate for utilization in TVWS applications.