• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.274-274
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• 2007

• ETRI Journal
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• v.35 no.5
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• pp.827-837
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• 2013

In this paper, we present wideband common-mode (CM) noise suppression using a vertical stepped impedance electromagnetic bandgap (VSI-EBG) structure for high-speed differential signals in multilayer printed circuit boards. This technique is an original design that enables us to apply the VSI-EBG structure to differential signals without sacrificing the differential characteristics. In addition, the analytical dispersion equations for the bandgap prediction of the CM propagation in the VSIEBG structure are extracted, and the closed-form expressions for the bandgap cutoff frequencies are derived. Based on the dispersion equations, the effects of the impedance ratio, the EBG patch length, and via inductances on the bandgap of the VSI-EBG structure for differential signals are thoroughly examined. The proposed dispersion equations are verified through agreement with the full-wave simulation results. It is experimentally demonstrated that the proposed VSI-EBG structure for differential signaling suppresses the CM noise in the wideband frequency range without degrading the differential characteristics.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.251-256
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• 2004

A stable reference voltage generator is necessary to the infrared image signal readout circuit(ROIC) to improve noise characteristics in comparison with signals originated from infrared devices, that is, to gain good images. In this study, bandgap reference circuit operating at cryogenic temperature of 77K for Infrared image ROIC(readout integrated circuit) was propose. Most of bandgap reference circuits which are presented so far operate at room temperature, and they are not suitable for infrared image ROIC operating at liquid nitrogen temperature, 77K. To design bandgap reference circuit operating at cryogenic temperature, the parameter characteristics of used devices as temperature change are seen, and then bandgap reference circuit is proposed with considering such characteristics. It demonstrates practical use possibility through taking measurements and estimations.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.4
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• pp.528-533
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• 2016

A low voltage high PSRR CMOS Bandgap circuit capable of generating a stable voltage of less than 1 V (0.8 V and 0.5 V) robust to Process, Voltage and Temperature (PVT) variations is proposed. The high PSRR of the circuit is guaranteed by a low-voltage current mode regulator at the central aspect of the bandgap circuitry, which isolates the bandgap voltage from power supply variations and noise. The isolating current mirrors create an internal regulated voltage $V_{reg}$ for the BG core and Op-Amp rather than the VDD. These current mirrors reduce the impact of supply voltage variations. The proposed circuit is implemented in a $0.35{\mu}m$ CMOS technology. The BGR circuit occupies $0.024mm^2$ of the die area and consumes $200{\mu}W$ from a 5 V supply voltage at room temperature. Experimental results demonstrate that the PSRR of the voltage reference achieved -118 dB at frequencies up to 1 kHz and -55 dB at 1 MHz without additional circuits for the curvature compensation. A temperature coefficient of $60 ppm/^{\circ}C$ is obtained in the range of -40 to $120^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.150-150
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• 2010

비휘발성 메모리의 구조는 ONO($SiO_2$, $SiN_X$, $SiN_XN_Y$), 혹은 NNO($SiN_X$, $SiN_X$, $SiN_XN_Y$)등으로 구성된 blocking layer, charge storage layer, tunneling layer 등이 일반적이다. 본 연구에서 제작된 OSO구조는charge storage layer를 a-Si을 사용한 것으로, 기존에 사용되던 charge storage layer인 $SiN_x$ 대신에 a-Si:H 를 사용하였다. 최적의 전하 저장층 조건을 알기 위하여 가스비에 따른 raman 및 bandgap 측정, 그리고 C-V 통하여 트랩된 전하 저장량 및 flatband 전압의 shift 값을 측정 및 분석하였다. 실험 결과, bandgap이 작아 band edge 저장 가능하며, SiNx 와 마찬가지로 a-Si:H 내 트랩에 저장이 가능하였다. 또한 $SiO_2$/a-Si:H와 a-Si:H/SiOxNy 계면의 결함 사이트에 전하의 저장되며, bandgap이 작아 트랩 또는 band edge에 위치한 전하들이 높은 bandgap을 가지는 blocking 또는 tunneling layer를 통하여 빠져 나오기 어려운 특성이 있었다. 본 연구에서는 최적의 전하 저장 층 조건을 알기 위하여 가스비에 raman 및 bandgap 측정, 그리고 C-V 통하여 트랩된 flatband 전압의 shift 값을 측정하여 결과를 논의하였다. 또한 OSO 구조의 두께에 있어 MIS 결과와 poly-Si 상에 실제 제작된 NVM 소자의 switching 특성을 논의하였다.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1716-1724
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• 2018

Single crystal of organic lead halide ($CH_3NH_3PbX_3$; $CH_3NH^+_3$ = methylammonium (MA), $X=Cl^-$, $Br^-$, $I^-$) is the best candidate for material intrinsic property studies due to no grain boundary and high crystal quality than the film having a lot of grain boundary and surface defects. The representative crystallization methods are inverse temperature crystallization (ITC) and anti-solvent vapor assisted crystallization (AVC). Herein, we report bandgap modulated organic lead halide single crystals having a bandgap ranging from ~ 2.1 eV to ~ 3 eV with ITC and AVC methods. The bandgap modulation was achieved by controlling the solvents and chloride-to-bromide ratio. Structural, optical and compositional properties of prepared crystals were characterized. The results show that the crystals synthesized by the two crystallization methods have similar properties, but the halide ratios in the crystals synthesized by the AVC method are controlled more quantitatively than the crystals synthesized by ITC.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.91-95
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• 2001

This paper presents that photonic bandgap structures suppressing the propagation of surface waves can improve the performance of the patch antennas on thick high dielectric constant substrate. The forbidden propagation of surface wave due to the photonic bandgap enhances the radiation efficiency and reduce the back radiation drastically with maintaining the small size and wide bandwidth of the antennas.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.413-422
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• 2002

A novel photonic bandgap(PBG) structure is proposed and measured for wide bandgap and compact circuit applications. The proposed structure realizes the ultra-wideband bandgap(2-octave) characteristics by superposing two different PBG structures into a coupled double-plane configuration. A low pass filter fabricated using 3-period of the PBG cells shows 2-octave 10 ㏈ stopband from 4.3 to 16.2 ㎓ and 0.2 ㏈ insertion loss in the passband. Moreover, we confirmed that 44∼70 % size reduction can be achieved using the proposed PBG structures. We expect this novel double-plane PBG structure is widely used for compact and wideband circuit applications, such as compact high-efficiency power amplifiers using harmonic tuning techniques.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12B
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• pp.1754-1757
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• 2001

In this paper, a R-band hybrid amplifier with the coplanar waveguide(CPW) and the photonic bandgap(PBG) structure is designed and fabricated. The PBG and the CPW techniques are simultaneously employed in amplifier to improve the power added efficiency(PAE) and the IMD(Intermodulation Distortion) in R-band. In this paper, the PBG structures are optimized to obtain matching network. The output impedance of amplifier and the input impedance of PBG are matched to minimize the return loss. The PAE and the IMD were improved 15% and 4.5dB compared with the conventional amplifier, respectively.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.346-348
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• 2014

A dispersion analysis is performed to estimate the stopband characteristics of electromagnetic bandgap (EBG) structures with defected ground structures (DGS) of various shapes. Design guidelines are suggested for both elliptical and rectangular DGS patterns that result in a maximum stopband bandwidth for a given perforation area. This method provides a basis for numerical optimization techniques that can be used in synthesizing DGS shapes to meet bandgap requirements and layout constraints.