• 대한전자공학회논문지SD
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• 제41권7호
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• pp.89-96
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• 2004

넓은 범위의 전압-제어 발진기 및 자동 이득 조절기의 실현을 위한 고선형 전압-제어 전류원(VCCS) 회로를 제안하였다. 제안한 VCCS는 전압 입력을 위해 이미터 폴로워, 전류 출력을 위해 이미터가 결합된 두 개의 공통-베이스 증폭기, 그리고 넓은 범위의 전류 출력과 높은 선형성을 얻기 위해 두 증폭기를 결합한 전류 미러로 구성된다. VCCS의 회로는 별도의 바이어스회로가 없이 단지 5개의 트랜지스터와 1개의 저항기만 사용하였다. 시뮬레이션 결과 제안한 VCCS는 5V의 공급전압에서 1V에서 4.8V까지의 제어-전압에 대하여 최대 0A에서 300㎃까지의 전류를 출력할 수 있다. 0㎃에서 300㎃의 출력 전류의 최대 선형 오차는 1.4 %이였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권4호
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• pp.318-330
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• 2013

This paper presents a high-linearity low-noise small-size programmable gain amplifier (PGA) based on a new low-noise low-distortion differential amplifier and a proposed reconfiguration technique. The proposed differential amplifier combines an inverter-based differential pair with an adaptive biasing circuit to reduce noise and distortion. The reconfiguration technique saves the chip size by half by utilizing the same differential pair for the input transconductance and load-stage, interchangeably. Fabricated in $0.18-{\mu}m$ CMOS, the proposed PGA shows a dB-linear control range of 21dB in 16 steps from -11 dB to 10 dB with a gain error of less than ${\pm}0.33$ dB, an IIP3 of 7.4~14.5 dBm, a P1dB of -7~1.2 dBm, a noise figure of 13dB, and a 3-dB bandwidth of 270MHz at the maximum gain, respectively. The PGA occupies a chip area of $0.04mm^2$ and consumes only 1.3 mA from the 1.8 V supply.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(1)
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• pp.450-455
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• 1995

A three-dimensional numerical tool is developed to calculate the potential distribution, electric field, and conductance for any types of conductance probes immersed in the wavy liquid film with various shapes of its free surface. The tool is validated against various analytical solutions. It is applied to find out the characteristics of the wire-wire probe, the flush-wire probe and the flush-flush probe in terms of resolution, linearity, and sensitivity. The wire-wire probe shows high resolution and excellent linearity for various film thickness, but comparably low sensitivity for low film thickness fixed. The flush-wire probe shows good linearity and high sensitivity for varying film thickness, but resolution degrading with an increase in film thickness. In order to check the applicability of the three types of probes in the real situation, the Korteweg-de Vries(KdV) two-dimensional solitary wave is simulated. The wire-wire probe is strongly affected by the installation direction of the two wires; when the wires are installed perpendicularly to the flow direction, the wire-wire probe shows large distortion of the solitary wave. In order to measure the transverse profile of waves, the wire-wire probes and the flush-wire probes are required to be separately installed 2mm and 2mm, respectively.

• 한국통신학회논문지
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• 제22권7호
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• pp.1579-1589
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• 1997

This paper introduces a monolithic chip 3.3V high-performance continuous-tune filter used in a CDP that can reconstruct the PDM or PWM signal output of a .SIGMA..DELTA. D/A converter. We also mentioned an active RC filter structure and filter order satisfying high-linearity and the design specification. In desigining the OP-AMP, using a structure that accepts some distortion we could reduce the chip area, and reducing the DC path using a new biascircuit gave us better power performance. The designed.SIGMA..DELTA. D/A converter post-processing filter does its smoothering operations and reconstructs the data without reducing the performance of the system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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• pp.192-196
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• 2002

This paper describes on the fabrication and characteristics of a metal thin-film pressure sensor based on Cr strain-gauges for harsh environment applications. The Cr thin-film strain-gauges are sputter-deposited onto a micromachined Si diaphragms with buried cavity for overpressure protectors. The proposed device takes advantages of the good mechanical properties of single-crystalline Si as diaphragms fabricated by SDB and electrochemical etch-stop technology, and in order to extend the operating temperature range, it incorporates relatively the high resistance, stability and gauge factor of Cr thin-films. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.097~1.21 $mV/V{\cdot}kgf/cm^2$ in the temperature range of $25{\sim}200^{\circ}C$ and the maximum non-linearity is 0.43 %FS.

• 대한디지털의료영상학회논문지
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• 제13권1호
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• pp.27-32
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• 2011

The conventional types of X-ray generators were bulky in physical size and heavy in weight, and the control accuracies of the output voltages were not always satisfactory. The high frequency switching inverter and converter technology on power conversion and control systems have been greatly closed up introducing power semiconductor devices. To decreasing the volume and the weight of high voltage transformer, and to stabilize ripple. In this paper, the newly developed x-ray generator in a low cost using duty modulation PWM inverter. This system verify improved performance by stabilize ripple of X-ray tube voltage and compared the reproducibility, linearity and dose in single phase, three phase and PSU.

• 대한전자공학회논문지TC
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• 제48권1호
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• pp.50-54
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• 2011

본 논문에서는 고출력 증폭기의 출력 정합단에서 발생하는 2차, 3차 고조파 성분을 억제하여 단일 고출력 증폭기의 선형성을 개선시키고 $3^{rd}$ IMD의 전치 왜곡에 의한 선형성 개선 PAM (Power Amplifier Module)을 제안하였다. 고조파를 억제하기 위해 정합회로는 메타전자파 구조를 갖도록 설계되었으며 2, 3차 고조파가 각각 27 dBc 이상 억제되었다. $3^{rd}$ IMD의 전치 왜곡은 구동 증폭기에서 발생하는 $3^{rd}$ IMD의 위상을 조절하여 -30도가 되도록 하였으며 이때 고출력 증폭기에서 발생되는 $3^{rd}$ IMD와 상쇄를 일으켜 고출력 증폭기 보다 6 dBc 이상 개선된 고조파 성분을 갖도록 설계되었다. 제안된 PAM은 36.98 dBm의 출력 전력과 21.6 dB의 전력 이득, 29.4 %의 전력 효율을 얻었으며 2차 고조파가 -53 dBc로 참조 증폭기에 비해 20dBc 이상 억제되는 특성을 얻었다.

• 한국의류산업학회지
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• 제10권4호
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• pp.566-571
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• 2008

Frictional sounds of 8 vapor permeable water repellent fabrics by sound generator were recorded and analyzed through FFT fast Fourier transform analysis. The frictional Sounds were quantified by calculating level pressure of total sound(LPT), the level range(${\Delta}L$) and the frequency difference(${\Delta}f$). Mechanical properties were measured by KES-FB. LPT values of specimens finished wet coating were higher than those of other kinds of finishing. ${\Delta}L$ values of specimens laminated were highest. Absolute values of ${\Delta}f$ were high in the cire finished and laminated specimens. Values for bending rigidity, shear stiffness and energy required for the compression of coated specimens increased compared with the cire finished and laminated specimens. Laminated specimens had high values of frictional coefficient and low values of surface roughness. Relationship between frictional sounds and mechanical properties analysed by use of correlation coefficients and stepwise regression. LPT showed significant correlation with elongation, tensile energy, geometrical roughness, weight and thickness. ${\Delta}L$ was highly correlated with tensile linearity, frictional coefficient, and ${\Delta}f$ with tensile linearity, weight and thickness. LPT were revealed to be explained by elongation and weight. ${\Delta}L$were predicted by tensile linearity, and ${\Delta}f$ by tensile linearity and thickness.

• 한국전자파학회논문지
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• 제27권1호
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• pp.50-59
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• 2016

본 논문은 $0.11{\mu}m$ CMOS 공정을 이용한 4세대 통신용 광대역 고 선형 전력 증폭기의 설계와 구현에 관해 기술한다. 1:2 트랜스포머(transformer)를 사용하여 출력단 매칭을 구현하였고, 인터 스테이지(inter-stage) 매칭에서 선형성을 고려한 설계가 포함되었다. 1.8 GHz에서 2.3 GHz까지, 10 MHz의 대역폭을 가지는 LTE 16-QAM 신호를 이용하여 측정한 결과, 인접채널 누설 비(ACLR)가 -30 dBc 이하일 때 27.3 dBm 이상의 선형 출력 전력을 얻을 수 있었고, 같은 조건에서 입력 신호 전력을 고려한 효율(PAE)은 최소 26.1 %로 나타남을 확인하였다.

• 한국전자파학회논문지
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• 제27권2호
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• pp.220-223
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• 2016

본 논문에서는 캐스코드(cascode) 구조에 트랜지스터를 추가하여 잡음 특성을 유지하면서 높은 선형성을 갖는 저잡음 증폭기 구조를 제안하고 설계하였다. 제안한 구조는 트랜지스터의 사이즈 최적화를 통해 잡음원을 최소화 했으며, 전류원분리(current bleeding) 효과를 주어 선형성을 개선하였다. 저잡음 특성에 유리한 $0.5{\mu}m$ pHEMT 공정을 이용해 제작된 저잡음 증폭기는 1.8~2.6 GHz의 동작 대역에서 30.8 dBm의 $OIP_3$, 15.0 dB의 이득, 1.1 dB의 NF, 11.6 dB/10.4 dB의 입출력 반사 손실 특성을 보였다.