• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.194-201
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• 2015

A frequency modulated ultra-wideband (FM-UWB) transmitter with a high-robust relaxation oscillator for subcarrier generation and a dual-path Ring VCO for RF FM is proposed, featuring low power and low complexity. A prototype 3.65-4.25 GHz FM-UWB transceiver employing the presented transmitter is fabricated in $0.18{\mu}m$ CMOS for short-range wireless data transmission. Experimental results show a bit error rate (BER) of $10^{-6}$ at a data rate of 12.5 kb/s with a communication distance of 60 cm is achieved and the power dissipation of 4.3 mW for the proposed transmitter is observed from a 1.8 V supply.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.251-255
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• 2003

In this paper, a miniaturized directional coupler utilizing lumped element is proposed as a interdigital capacitor. The traditional miniaturization technique of transmission line realized a utilizing MIM(Metal-Insulator-Metal) capacitor on CPW(Coplanar Waveguide). However, we present a simplified design procedure without additional manufacturing process utilizing interdigital capacitor on microstrip with ease of design. The similar characteristics between the conventional directional coupler with ${\lambda}/4$ transmission line and the miniaturized directional coupler with ${\lambda}/8$ transmission line are validated through simulation and measurement results. Miniaturization rate of total size is about 25% while coupled line is about 60%. As a result, this proposed directional coupler can reduce the size of mobile communication system at 2 GHz.

• Journal of electromagnetic engineering and science
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• v.7 no.4
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• pp.175-182
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• 2007

In this paper, a study on the reflector type frequency doubler, to suppress the undesired harmonics, is presented. A 12 to 24 GHz reflective frequency doubler is simulated and experimented. Design procedure of the frequency doubler with reflector is provided and the frequency doubler with good spectral purity is fabricated successfully. It has harmonic suppression of the $40{\sim}50\;dBc$ in the $1^{st}$ harmonic and the $50{\sim}60\;dB$ in the $3^{rd}$ harmonic with no additional filter. And, it has conversion gain with the input power of 0 dBm over bandwidth of 500 MHz. A NEC's ne71300(N) GaAs FET is used and the nonlinear model(EEFET3) using IC-CAP program is extracted for harmonic load pull simulation. Good agreement between simulated and measured results has been achieved.

• Progress in Superconductivity
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• v.1 no.1
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• pp.42-46
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• 1999

A high-temperature superconducting 1.78 GHz bandpass filter, designed for PCS applications, is presented. The structure consists of microstrip pseudo-lumped elements, which enables miniaturization of the filter. A 5-pole microstrip filter could be realized on a 37 mm $\times$ 9 mm $LaAlO_3$ substrate, using double-sided high-temperature superconducting $YBa_2Cu_3O{7-\delta}$ thin film. This filter showed 0.7 % fractional bandwidth, 0.3 dB insertion loss, and 12 dB return loss in the passband at 60 K.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3050-3065
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• 2016

Neural networks (NNs) are extensively used in applications requiring signal classification and regression analysis. In this paper, a NN based threshold selection algorithm for 60 GHz millimeter wave (MMW) time of arrival (TOA) estimation using an energy detector (ED) is proposed which is based on the skewness, kurtosis, and curl of the received energy block values. The best normalized threshold for a given signal-to-noise ratio (SNR) is determined, and the influence of the integration period and channel on the performance is investigated. Results are presented which show that the proposed NN based algorithm provides superior precision and better robustness than other ED based algorithms over a wide range of SNR values. Further, it is independent of the integration period and channel model.

• ETRI Journal
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• v.28 no.5
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• pp.607-614
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• 2006

This paper presents a new class of microstrip slow-wave open-loop resonator filters with reduced size and improved stopband characteristics. A comprehensive treatment of both ends loaded with triangular and rectangular ends is described, leading to the invention of a microstrip slow-wave open-loop resonator. Two-resonator and four-resonator bandpass filters are designed at the operating frequency of about 2 GHz, and a bandwidth of 60 MHz. The size of the slow-wave open-loop resonator is optimized from the standpoint of the unloaded Q-factor. The filters are not only compact in size due to the slow-wave effect, but also have a wider upper stopband resulting from the dispersion effect. The filter designs of this type are described in details. The experimental results are demonstrated and discussed.

• Proceedings of the Korea Association of Information Systems Conference
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• 2004.11a
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• pp.244-250
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• 2004

최근 정보화, 멀티미디어 시대를 맞이하여 기존의 음성 신호 이외에 화상 회의, 고화질 디지털 TV, 영상 전화와 같이 다양한 멀티미디어 정보를 고품질로 전송할 수 있는 광대역 밀리미터파 무선통신이 각광받고 있다. 밀리미터파 대역은 문화, 군사 및 항공우주 분야 등에 널리 활용될 수 있어 관련 소자 및 시스템 개발에 많은 노력을 기울이고 있으며 최근 상업적 필요성이 대두되면서 기지국과 가입자간의 통신로를 무선화하는 BWLL(Broadband Wireless Local Loop)과 무선 LAM 및 차량 충동방지 시스템 등 민수용 부문의 응용기술이 점차 보급됨에 따라 밀리미터파 기술은 민${\cdot}$군 겸용기술로 중요성이 부각되고 있다. 본 논문은 이동과 개인휴대 통신 시스템용 60GHz 밀리미터파 대역의 주요 응용 시스템은 도로, 철도 운송 시스템뿐만 아니라 실내${\cdot}$외용 밀리미터파 전파에 대해 소개한다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.169-170
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• 2006

A band pass filter for the V-band application with unique circuit and structure was designed and implemented using 2-metals, 3-BCB layers. In the mean while the effective electrical conductivity of metal layer was extracted and its value was $4{\times}10^7S/m$. The insertion loss of band pass filter at 60 GHz was 3.0 dB and group delay was below 0.1 ns.

• Journal of electromagnetic engineering and science
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• v.1 no.1
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• pp.18-23
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• 2001

A fast-sweep broadband FM reflectometer system has been successfully developed and operacted at the DIII-D tokamak, producing reliable density Profiles with excellent spatial (1 $\leq$ cm) and temporal resolution (~100 $\mu$ s). The system uses a solid-state microwave oscillator and an active quadrupler, covering full Q-band frequencies (33~50 GHz) and providing relatively high output power (20~60 mW). The system hardware allows fu11band frequency sweep in 10 $\mu$ s, but due to digitization rate limit on DIII-D, sweep time was limited to 75~100 $\mu$ s. Fast frequency sweep has helped to reduce density fluctuation effects on the reflectometer phase measurements, thus improving reliability for individual sweeps. The fast-sweep system with high spatial and temporal resolution has allowed to measure fast-changing edge density profiles during plasma ELMS and L-H transitions, thus enabling fast-time sca1e physics studies.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.1
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• pp.53-60
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• 2009

$ZrTiO_4$ dielectric thin films were coated by metal-organic decomposition, and annealed by rapid thermal processing up to $900^{\circ}C$ for their crytallization. Crystallized single-phase $ZrTiO_4$ thin films were fabricated above the annealing temperature of $800^{\circ}C$, but their grains were randomly oriented without specific textured orientation. Best dielectric properties were presented by the sample annealed at $800^{\circ}C$ which had crystalline structure and flat surface. Dielectric constant of the film was maintained at 32 throughout full frequency range up to 6 GHz, and dielectric loss was varied between 0.01 and 0.04.