• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.146-149
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• 2000

SiGe HUT뜰 이용하여 Cellular 주파수 대역(824-849 MHz)에서 MMIC 상향 주파수 혼합기와 가변이득 증폭기를 설계하였다. 동작 전압은 2.7 V 이며, 이중평형 구조의 상향 주파수 혼합기는 12 dB의 변환이득, -0.6 dBm의 1dB 이득압축 출력전력, 30 dB 이상의 LO-RF 단자 격리도 특성, 1.25의 LO-VSWR. 1.34의 RF-VSWR을 가지며, 상호컨덕턴스형 가변이득 증폭기는 35 dB의 최대 선형이득, 13 dBm의 1dB 이득압축 출력전력, 42dB의 가변이득, 23dB의 3차 상호변조 교점 출력전력(OIP$_3$), 1.27의 입력 VSWR, 1.1의 출력 VSWR 특성을 보인다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.6
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• pp.835-840
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• 1993

In this paper a FET mixer is designed realized by small-signal S-parameter using microwave CAD, LINMIC + at Ku-band. The mixer has conversion gain 9.88dB at 14GHz RF, 1GHz IF, and + 1dBm LO imput. The maximum conversion gain is obtained 11.71dB at 1.1GHz. The result shows that the FET mixer does not need pre-and/or IF amplifier. The mixer maintains the desired conversion gain with low LO power level. The conversion gain of the mixer is higher than the available gain of a amplifier, which is experimentally verified.

• ICROS
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• v.17 no.1
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• pp.31-38
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• 2011

주파수 영역에서 제어기를 설계하기 위해서는 시스템의 대역폭, 초대 주파수 응답, 저주파에서의 이득, 고주파에서의 이득 감쇄 정도를 고려한다. 또한 나이퀴스트 선도, 보우드 선도 등을 활용하여 폐루프 제어 시스템의 이득여유, 위상 여유를 확보할 수 있도록 한다. 일반적으로 저주파 영역에서는 개루프의 이득이 기준치보다 크도록 하고, 고주파수 영역에서는 기준치보다 작도록 설계를 하며, 폐루프 응답에서 대역폭이 유지되고, 공진피크점의 응답 크기는 1에 비하여 과도하게 크지 않도록 설계를 한다.

• The Journal of the Acoustical Society of Korea
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• v.41 no.2
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• pp.218-226
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• 2022

The main characteristics of the underwater acoustic channel have varying multipath and fast fading. Especially, Frequency Shift Keying (FSK) signals with multiple frequency bands caused loss of information bits allocated on the specific frequencies due to selective fading phenomenon. Therefore, this paper proposes frequency gain control algorithm based on preamble error rates. The proposed algorithm estimates optimal gain value in the range of preamble error rate with less than 10 % for specific faded frequency. By employing turbo equalized FSK signals with rate of 1/3, the experiment was conducted on a lake in Munkyeong city with distance of 300 m to 500 m. The result confirms that packets are decoded successfully by applying proposed algorithm as increasing number of iterations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.8
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• pp.867-880
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• 1992

In this paper, a circuit design techniques for Improving the voltage gain of the GaAs MESFET single amplifier is presented. Also, various types of existing current mirror and proposed current mirror of new configuration are compared. To obtain the high differential mode gain and low common mode gain, bootstrap gain enhancement technique Is used and common mode feedback Is employed In the design of differential amplifier. The simulation results show that designed differential amplifier has differential gain of 57.66dB, unity gain frequency of 23.25GHz. Also, differential amplifier using common mode feedback with alternative negative current mirror has CMRR of 83.S8dB, stew rate of 3500 V /\ulcorners.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.2
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• pp.16-26
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• 2001

This paper develops the fast dynamic programming technique to construct the subband structure yielding the maximum coding gain for given filter bases and a given limit of implementation complexity. We first derive the unified coding gain which can be applied to non-orthogonal filter basis as well as orthogonal filter basis and to arbitrary subband decompositions. Then, we verify that the unified coding gains in real systems are monotonically increasing function for the implementation complexities which are proportional to the number of subbands. By using this phenomenon, the implementation complexity and the coding gain are treated in the same way as the rate and distortion function. This makes it possible to use the Lagrangian multiplier method for finding the optimal subband decomposition producing the maximum coding gain [or a given limit of implementation complexity.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1990_1991
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• 2009

본 논문은 뇌파와 같이 측정을 위해서 많은 수의 채널이 필요한 계측 장치에서 채널에 따른 증폭률의 차이를 보정하기 위해 동일한 입력을 가한 후 측정된 시간 영역의 신호를 주파수 영역으로 변환하고 주파수 영역에서의 신호를 분석하여 각 채널의 증폭률의 차이를 유도하고 유도된 증폭률의 차이를 보정하는 알고리즘을 소개한다. 본 논문은 다채널 시스템에서 측정된 신호를 주파수 스펙트럼으로 변환하는 단계와 스펙트럼에서 각 채널의 이득률을 분석하는 단계를 포함하는 다채널 시스템에서 채널간 이득률을 보정하는 방법을 제안한다.

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.243-249
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• 2007

I propose the excess noise suppressed optical sensor network using optical CDMA with gain saturated optical amplifier in order to increase number of sensors simultaneously connected to network. Simulation analyses confirm that the maximum number of sensors simultaneously connected to the optical sensor network can be largely increased by increasing the gain of gain saturated optical amplifier owing to the pression of access noises with the assignment of sweeping frequency of optical sensors within 10MHz. In the case of the requested SNR of 20dB and the sweeping frequency of 10MHz, the maximum number of sensors simultaneously connected to the optical sensor network can be increased four times as many as the conventional system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3614-3621
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• 2009

In this paper, A CMOS low-voltage current mode integrator is designed. The designed current-mode integrator is based on linear cascode circuit that is newly proposed in this paper. When it is compared with gain(43.7dB) and unity gain frequency(15.2MHz) of the typical current-mirror type current-mode integrator, the proposed linear cascode current-mode integrator achieves high current gain(47.8dB) and unity gain frequency(27.8MHz). And a 5th Chebyshev current-mode filter with 7.03MHz cutoff frequency is designed. The designed all circuits are simulated by HSPICE using 1.8V-$0.18{\mu}m$ CMOS technology.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.6
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• pp.1-5
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• 2010

We propose an algorithm which can classify the system should use a PI controller, which have a weak high frequency attenuation characteristics near the critical frequency. To classify the system, we use a time delay element to calculate a gain attenuation rate near the critical frequency. The proposed algorithm also can design PI controller with the given magnitude margin and phase margin specification. The proposed algorithm uses time delay element and saturation function to identify the one point information in frequency domain. We justify the proposed algorithm via the simulation.