• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
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• pp.84-87
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• 2000

In this paper, a high gain-broad bandwidth MMIC distributed amplifier was designed using cascaded single section distributed amplifier configuration. The PHEMT for this studies was fabricated at our lab The PHEMT has a 0.2 $\mu\textrm{m}$ gate length. a 80 $\mu\textrm{m}$ unit gate width and 4 gate fingers. A designed MMIC amplifier have higher S$\sub$21/ gain than the common distributed amplifier using the same number of active devices. From the simulated result, we obtained that the S$\sub$21/ gain of DC ∼ 20 GHz bandwidth was 15.6 dB and flatness was ${\pm}$0.9 dB, and input and output reflection coefficient were lower than -8 dB. The simulated gain shows an improvement 7.3 dB compared with those of conventional distributed amplifier. And the chip size is 2.0 ${\times}$ 1.2 $\textrm{mm}^2$.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.125-130
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• 2005

This paper suggests an efficient method of protection ratio calculation and shows some calculated results applicable to frequency coordination in microwave relay system networks, and the net filter discrimination (NFD) associated with Tx spectrum mask and overall Rx filter characteristics has been examined to obtain the adjacent channel protection ratio. The protection ratio comprises several factors such as C/N of modulation scheme, noise-to-interference ratio, multiple interference allowance, fade margins of multi-path and rain attenuation, and NFD. According to computed results for 6.7 GHz, 64-QAM, and 60 km at BER $10^{-6}$, fade margin and co-channel protection ratio are 41.1 and 75.2 dB, respectively, In addition, NFD for channel bandwidth of 40 MHz reveals 28.9 dB at the first adjacent channel, which results in adjacent channel protection ratio of 46.3 dB. The proposed method provides some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter wave relay system networks.

• 한국정보전자통신기술학회논문지
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• 제9권6호
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• pp.630-636
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• 2016

In this paper, a novel triple-mode cavity structure, designed for compactness and operating at 850 MHz, is analyzed. A cylindrical dielectric resonator is loaded into a metallic cylindrical cavity. Previous study has been focused on the analysis of the cylindrical dielectric resonator, but in this paper, the effect of the cylindrical metallic cavity has been analyzed. Enclosing the dielectric resonator inside the metallic cavity increases the resonant frequency of the dielectric resonator; however, this increases the quality factor and introduces the possibility of installing coupling screws. The principle of generation of triple-mode was investigated by parametric analysis. The generated triple-mode is TE011 mode and two orthogonally generated HEM121 modes. By adjusting the radius of the dielectric resonator, the height of the dielectric resonator, or the radius of the cylindrical metallic cavity, three modes could be coincided. However, the height of the metallic cavity keeps three modes separated. The mode characteristics of the proposed cavity are analyzed using a full-wave electromagnetic (EM) simulation. The proposed triple-mode cavity could be developed to triple-mode filter using a coupling screw, and the commercial application for the miniaturized filter below 1 GHz could be expected.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2004년도 하계학술대회
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• pp.226-229
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• 2004

본 논문은 초고주파 영역에서 개방 단말 동축선을 대신해서 복소 유전율을 측정할 수 있는 MEMS 프로브와 그 응용예로 MEMS 프로브 어레이를 제안한다. MEMS 프로브는 기존의 동축선 프로브와 달리 커넥터와의 연결이 간단하여 일회용으로 프로브를 사용할 수 있다는 점에서 의료용으로 사용할 수 있는 가능성이 있다. 샘플의 유전율 분포를 구하기 위해서 기존의 센서는 반복 접촉을 요구하고 이로 인한 번거로움과 측정 오차를 줄일 목적으로 MEMS 프로브 어레이를 개발 하였다. MEMS 프로브 어레이는 RF 스위치를 사용하여 다수의 측정 포인트를 한번의 센서 접촉으로 측정할 수 있는 새로운 개념의 프로브이다. 1GHz부터 40GHz까지의 광대역에서 0.9% 식염수의 유전율을 측정하여 MEMS 프로브의 성능을 검증하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.200-200
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• 2008

This paper reports on electrical characterization by IDC pattern using BST$(Ba_{0.5}Sr_{0.5}TiO_3)$ thin film. BST thin films have been deposited on $Al_2O_3$ Substrates by Nd-YAG pulsed laser deposition with a 355nm wavelength at $700^{\circ}C$. The post deposition annealing at $750^{\circ}C$ in flowing $O_2$ atmosphere for I hours. The capacitance of IDC patterns have been measured from 1 to 10 GHz as a function fo electric field (${\pm}40$ KV/cm) at room temperature using interdiigitated Au electrodes deposited on top of BST. The IDC patterns have three type of fingers number. For the finger paris was increased onto $Al_2O_3$, the capacitance increased. The capacitance of 5 pairs finger was 0.3pF and 10 pairs finger was 0.9pF.

• 전자공학회논문지D
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• 제35D권4호
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• pp.9-17
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• 1998

BiNbO$_{4}$ ceramics with 0.07wt% V$_{2}$O$_{5}$ and 0.03wt% CuO (BNC3V7) sintered at 900 .deg. C where it is possible for these to be co-fired with ag electronde. Dielectric constant of 44.3 TCF (Thermal Coefficient of resonance Frequency) of 2 ppm/.deg. C and Qxf value 22,000 GHz can be obtained from BNC3V7. the laminatedchip LC filter is indispensible to the minimaturization of PCS (Personal Communication System) terminals. Therefore, multilayer type BPF has been fabricated by screen-printing with silver electrode after tape casting. The simulated characteristics of the fabricated filters sintered at 900.deg. C werecomparedwith the designed ones. for Band Pass Filter widths was similar that ofdesigned ones. For Low Pass Filter (LPF), insertion loss value of band pass widths (2.4 dB) which is a few higher than that of designed (1dB), but characteristization of band pass widths was similar that of designed ones.s.of designed ones.s.

• ETRI Journal
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• 제29권4호
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• pp.421-429
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• 2007

This paper presents a direct-conversion CMOS transceiver for fully digital DS-UWB systems. The transceiver includes all of the radio building blocks, such as a T/R switch, a low noise amplifier, an I/Q demodulator, a low pass filter, a variable gain amplifier as a receiver, the same receiver blocks as a transmitter including a phase-locked loop (PLL), and a voltage controlled oscillator (VCO). A single-ended-to-differential converter is implemented in the down-conversion mixer and a differential-to-single-ended converter is implemented in the driver amplifier stage. The chip is fabricated on a 9.0 $mm^2$ die using standard 0.18 ${\mu}m$ CMOS technology and a 64-pin MicroLead Frame package. Experimental results show the total current consumption is 143 mA including the PLL and VCO. The chip has a 3.5 dB receiver gain flatness at the 660 MHz bandwidth. These results indicate that the architecture and circuits are adaptable to the implementation of a wideband, low-power, and high-speed wireless personal area network.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.193-196
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• 2000

A new type low-pass filter design method based on a coupled line and transmission line theory is proposed to suppress harmonics by attenuation poles in the stop band. The design formula are derived using the equivalent circuit of a coupled transmission line. The new low-pass filter structure is shown to have attractive properties such as compact size, wide stop band range and low insertion loss. The seventh-order low-pass filter designed by present method has a cutoff frequency of 0.9 CHz with a 0.01 dB ripple level. The coupled line type low-pass filter with strip line configuration was fabricated by using a high-temperature superconducting (HTS : YBa$_2$Cu$_3$O$_{7-{\delta}}$ thin film on MgO(100) substrate. Since the HTS coupled tine type low-pass filter was proposed with five attenuation poles in stop band such as 1.8, 2.5, 4, 5.5, 6.2 GHz. The fabricated low-pass filter has improved the attenuation characteristics up to seven times of the cutoff frequency.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.67-70
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• 2006

This paper deals with a single crystalline silicon (SCS) RF MEMS switch for telecommunication system applications. The proposed SCS switch was fabricated using a silicon-on-glass (SiOG) process and its performances in terms of RF responses, switching time, lifetime were characterized. The proposed SCS switch consists of movable plates, mechanical spring structures, which are composed of robust SCS, resulting in mechanically good stability, The measured actuation voltage was 30 V, and with this applied voltage, the insertion loss and isolation characteristics were measured to be 0.05 and 44.6 dB at 2 GHz respectively. The measured switch ON and OFF time were 13 and $9{\mu}s$, respectively. The lifetime of the fabricated switch was tested. Even after over 1 billion cycles repeated ON/OFF actuations, the switch maintained its own characteristics.

• 한국자기학회지
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• 제22권3호
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• pp.73-78
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• 2012

본 연구에서는 Argyres-Sigel의 투영 연산자 방법을 단일 벽 탄소 나노튜브(SWNT)의 zigzag(10,0)에 직접 적용하여 이를 운동방정식의 형태로 만들어 선모양 함수를 구하는 방법을 사용하였다. 선모양 함수의 실수 부분인 선 너비는 저온 영역(T < 200K)에서 온도의 영향에 거의 무관한 것으로 조사되었다. 이는 온도에 관여하는 페르미-디랙 분포함수가 선모양 함수에 거의 영향을 작용하지 않기 때문인 것으로 생각된다. 고온 영역(T > 200K)에서는 선 너비가 다소 단조롭게 증가하는 것으로 나타났으며, 이는 음향 포논의 영향에 기인하는 것으로 보인다. 그리고 SWNT의 전자스핀이완 시간은 $1.4{\times}10^{-6}\;s$으로 계산되었다.