• 한국통신학회논문지
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• 제24권7A호
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• pp.947-954
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• 1999

본 논문에서는 저렴하고 성능이 우수하면서 간단한 구조를 갖는 새로운 저 위상잡음 유전체 공진 병렬 궤환 발진기가 제안된다. 제안된 유전체 공진 병렬 궤환 발진기는 저잡음 증폭기, 전력증폭기, 전력 감쇠기, 전력 분배기, 그리고 두 개의 마이크로스트립 선로와 결합된 유전체 공진기로 이루어지는 병렬 유전체 공진 궤환 요소로 구성된 궤환 루프 발진기 구조를 가지고 있다. 유전체 공진 병렬 궤환 발진기의 측정된 위상잡음은 캐리어 주파수 10.75 GHz, 오프셋 주파수 1kHz에서 81dBc/Hz 보다 작게 나타났으며, 온도에 따른 주파수 안정도는 주변온도 -4$0^{\circ}C$에서 6$0^{\circ}C$까지 +/- 200kHz를 나타내었다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제2권1호
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• pp.30-40
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• 2002

A 2.45GHz double-balanced modified Gilbert-type CMOS up-conversion mixer design is introduced, where the PMOS current-reuse bleeding technique is demonstrated to be efficient in improving conversion gain, linearity, and noise performance. An LO buffer is included in the mixer design to perform single-ended to differential conversion of the LO signal on chip. Simulation results of the design based on careful modeling of all active and passive components are examined to explain in detail about the characteristic improvement and degradation provided by the proposed design. Two kinds of chips were fabricated using a standard $0.35\mu\textrm$ CMOS process, one of which is the mixer chip without the LO buffer and the other is the one with it. The measured characteristics of the fabricated chips are quite excellent in terms of conversion gain, linearity, and noise, and they are in close match to the simulation results, which demonstrates the adequacy of the modeling approach based on the macro models for all the active and passive devices used in the design. Above all the benefits provided by the current-reuse bleeding technique, the improvement in noise performance seems most valuable.

• 대한전자공학회논문지TC
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• 제40권9호
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• pp.392-397
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• 2003

Lange 커플러를 이용한 반사구조 위상변위기는 광대역에서 위상변이를 얻는데 사용되는 회로이다. 이런 5-비트 반사구조에서 33.75°는 대개 11.25°와 22.5°를 동시에 "on"시켜서 얻는 방법이 사용되어져 왔다. 본 논문은 33.75° 위상특성을 개선하기 위하여 GaAs PM 다이오드와 리액티브 부하로 구성된 별도의 회로를 제안하였으며 MMIC로 구현하였다. 2-6 GHz에서 제안된 회로는 기 발표 논문에 비하여 33.75°를 기준으로 할 때 평균 4.7° 개선된 특성을 얻었다. 기존 회로와 비교할 때 삽입손실 및 반사손실은 거의 변화가 없었다.

• 전자공학회논문지
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• 제50권11호
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• pp.36-40
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• 2013

본 논문에서는 덤벨형 결함 접지면 구조를 갖는 복합 좌-우향(CRLH) 전송선로를 이용하여 초광대역 대역통과 여파기를 설계하였다. 결함 접지면 구조와 마이크로스트립 인터디지털 캐패시터를 이용하여 CRLH 전송선로를 구현하고 이것을 이용하여 필터를 설계하였다. CRLH 전송선로는 저역통과와 고역통과 필터의 복합적인 특성을 나타내는데, 그것들의 차단주파수를 잘 조절함으로써 초광대역의 대역통과 필터의 특성을 얻을 수 있다. UWB 필터 특성을 얻기 위해 1, 2, 4, 8 셀을 갖는 CRLH 전송선로에 대해 시물레이션하였고, 본 논문에서는 결과를 검증하기 위해 4 셀 구조의 UWB 필터를 설계 제작하였다. 측정된 결과는 시뮬레이션 결과와 일치하며 5GHz 중심주파수에서 88%의 넓은 대역폭을 갖는다.

• Journal of electromagnetic engineering and science
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• 제13권2호
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• pp.93-103
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• 2013

This paper presented a novel approach for the design of a tunable dual-band bandpass filter (BPF) with independently tunable passband center frequencies and bandwidths. The newly proposed dual-band filter principally comprised two dual-mode single band filters using common input/output lines. Each single BPF was realized using a varactor-loaded transmission line resonator. To suppress the harmonics over a broad bandwidth, a defected ground structure was used at the input/output feeding lines. From the experimental results, it was found that the proposed filter exhibited the first passband center frequency tunable range from 1.48 to 1.8 GHz with a 3-dB fractional bandwidth (FBW) variation from 5.76% to 8.55%, while the second passband center's frequency tunable range was 2.40 to 2.88 GHz with a 3-dB FBW variation from 8.28% to 12.42%. The measured results of the proposed filters showed a rejection level of 19 dB up to more than 10 times the highest center frequency of the first passband.

• 한국전기전자재료학회논문지
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• 제13권10호
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• pp.840-846
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• 2000

In this work, small-size, high-performance solenoid-type RF chip inductors utilizing a low-loss Al$_2$O$_3$core material were investigated. The size of the chip inductors fabricated in this work were 15$\times$10$\times$0.7㎣, 2.1$\times$1.5$\times$10㎣, and 2.4$\times$2.0$\times$1.4㎣ and copper (Cu) wire with 40 ㎛ diameter was used as the coils. High frequency characteristics of the inductance, quality factor, and impedance of developed inductors were measured suing an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). It was observed that the developed inductors with the number of turns of 7 have the inductance of 33 to 100nH and exhibit the self-resonant frequency (SRF) of .26 to 1.1 GHz. The SRF of inductors decreases with increasing the inductance and the inductors have the quality factor of 60 to 80 in the frequency range of 300 MHz to 1.1 GHz. In this study, small-size solenoid-type RF chip inductors with high inductance and high quality factor were fabricated successfully. It is suggested that the thin film-type inductor is necessary to fabricate the smaller size inductors at the expence of inductance and quality factor values.

• ETRI Journal
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• 제40권1호
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• pp.26-38
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• 2018

To overcome considerable path loss in millimeter-wave propagation, high-gain directional beamforming is considered to be a key enabling technology for outdoor 5G mobile networks. Associated with beamforming, this paper investigates propagation power loss characteristics in two aspects. The first is beamwidth effects. Owing to the multipath receiving nature of mobile environments, it is expected that a narrower beamwidth antenna will capture fewer multipath signals, while increasing directivity gain. If we normalize the directivity gain, this narrow-beamwidth reception incurs an additional power loss compared to omnidirectional-antenna power reception. With measurement data collected in an urban area at 28 GHz and 38 GHz, we illustrate the amount of these additional propagation losses as a function of the half-power beamwidth. Secondly, we investigate power losses due to steering beam misalignment, as well as the measurement data. The results show that a small angle misalignment can cause a large power loss. Considering that most standard documents provide omnidirectional antenna path loss characteristics, these results are expected to contribute to mmWave mobile system designs.

• ETRI Journal
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• 제42권5호
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• pp.773-780
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• 2020

A 40 nm complementary metal oxide semiconductor carrier-aggregated drive amplifier with high linearity is presented for sub-GHz Internet of Things applications. The proposed drive amplifier consists of two high linear amplifiers, which are composed of five differential cascode cells. Carrier aggregation can be achieved by switching on both the driver amplifiers simultaneously and combining the two independent signals in the current mode. The common gate bias of the cascode cells is selected to maximize the output 1 dB compression point (P1dB) to support high-linear wideband applications, and is used for the local supply voltage of digital circuitry for gain control. The proposed circuit achieved an output P1dB of 10.7 dBm with over 22.8 dBm of output 3rd-order intercept point up to 0.9 GHz and demonstrated a 55 dBc adjacent channel leakage ratio (ACLR) for the 802.11af with -5 dBm channel power. To the best of our knowledge, this is the first demonstration of the wideband carrier-aggregated drive amplifier that achieves the highest ACLR performance.

• 대한전자공학회논문지SD
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• 제40권8호
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• pp.555-559
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• 2003

본 논문에서는 CMOS 소자의 RF 동작을 정확히 예측하기 위해 Si 표면에서의 메탈 라인 사이의 커패시턴스 효과와 표피효과 및 근접효과를 포함한 RF IC 설계를 위한 새로운 CMOS RF 모델을 처음으로 제시하였다. Si 표면에서의 메탈 라인 사이의 커패시턴스는 레이아웃에 기초하여 모델링하였으며, 표피효과는 메탈 라인의 등가회로에 병렬회로를 부가하여 사다리꼴 등가회로로 구현하였다. 근접효과는 사다리꼴 등가회로에서 교차 결합된 인덕턴스 사이의 상호 인덕턴스를 부가함으로써 모델링하였다. 제안된 RF 모델은 BSIM 3v3에 비해 측정 데이터와 잘 일치하였으며, GHz 영역에서 소자 동작의 주파수 종속성을 잘 보여주었다.

• 한국전기전자재료학회논문지
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• 제23권7호
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• pp.554-559
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• 2010

In this paper, we analyzed the frequency spectrum of radiated electromagnetic pulses generated by series arc- and corona- discharges as a basic study to develop an on-line diagnostic technique for power facilities installed inside closed-switchboards. To simulate series arc and corona discharges, five types of electrode system which consists of needle and plane electrodes were arranged. The experiment was carried out in an electromagnetic shielding room, and the measurement system consists of an ultra log antenna and an EMI receiver. From the experimental results, the frequency spectrum exists in ranges from 30 MHz to 2 GHz for a series arc discharge and 30 MHz to 1.2 GHz depending on defects for a corona discharge. The peak frequency of the series arc- and corona- discharges were 100 MHz to 160 MHz and 40 MHz to 80 MHz, respectively.