• 한국전자파학회논문지
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• 제13권10호
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• pp.982-988
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• 2002

본 논문은 통신방송위성 중계기용 Ku-대역 채널증폭기 시험모델의 설계와 제작과정을 요약하였다. 채널증폭기의 구조는 고정이득제어 모드에서는 전압제어형 감쇄기를 이용한 아날로그 이득 조절 방식을 사용하였으며 자동레벨조절 모드에서는 루프제어방식을 이용한 출력레벨 제한회로를 사용하였다. 설계된 채널증폭기는 전압제어형 PEN-다이오드 감쇄기와 온도보상회로 등의 최신 기술 등을 이용하였다. 측정된 특성은 설계치와 동일하게 28 dB의 이득조절 및 16 dB의 자동이득조절 범위를 갖는 것을 확인하였다. 설계된 시험모델은 인증을 거치면 Ku-대역 통신방송 위성중계기용 채널증폭기로 사용되어질 수 있다.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권11호
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• pp.550-556
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• 2001

The computerized cardiac analysis system, which acquires and analyzes the electrical activation signal propagating along the surface of the heart, is indispensible equipment for the open heart surgery and electrical cardiac study. In this paper, the design requirement and the electrical circuit analysis are performed to construct the multi-channel cardiac activation pre-amplifier necessary for a signal conditioning circuit. The general 64 channel configuration is expanded into 128 channels to enhance the spatial resolution on the mapped surface of the heart. The 128 channels pre-amplifier consists of input circuit, differential amplifier, right leg driven circuit and isolation part. It has distinct features; high voltage protection, leakage current limitation, isolation and the maximization of common mode rejection ratio with respect to the half-cell potential difference due to different electrode materials. The final pre-amplifier circuit is assembled with 8 boards, each of which composing of 16 channels.

• 한국전자통신학회논문지
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• 제5권2호
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• pp.180-184
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• 2010

본 논문에서는 다중 채널 심장 전기도 주 증폭기의 중요한 부분인 필터를 설계하고 시뮬레이션을 통하여 성능을 분석하였다. 주 증폭기는 샘플/홀더, 가변 고역통과 필터, 노치 필터, 가변 저역통과 필터로 구성된다. 필터는 기존의 64 채널의 공간 분해능을 향상시키기 위하여 128채널을 고려하여 설계되었다.

• 전기학회논문지
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• 제64권12호
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• pp.1737-1741
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• 2015

A multi-channel CMOS transimpedance amplifier(TIA) array is realized in a $0.18-{\mu}m$ CMOS technology for the applications of panoramic scan LADAR systems. Each channel consists of a PIN photodiode and a feed-forward TIA that exploits an inverter input stage followed by a feed-forward common-source amplifier so as to achieve lower noise and higher gain than a conventional voltage-mode inverter TIA. Measured results demonstrate that each channel achieves $76-dB{\Omega}$ transimpedance gain, 720-MHz bandwidth, and -20.5-dBm sensitivity for $10^{-9}$ BER. Also, a single channel dissipates the power dissipation of 30 mW from a single 1.8-V supply, and shows less than -33-dB crosstalk between adjacent channels.

• Journal of Advanced Marine Engineering and Technology
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• 제30권4호
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• pp.505-513
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• 2006

A linear power amplifier is particularly emphasized on the system using a linear modulations, such as 16QAM and QPSK with pulse shaping. because intermodulation distortion which causes adjacent channel interference and co-channel interference is mostly generated in a nonlinear power amplifier. In this paper, parameters of a linearization loop, such as an amplitude imbalance a phase imbalance and a delay mismatch, are briefly analyzed to get a specific cancellation performance and linearization bandwidth. Experimental results are presented for IMT-2000 frequency band. The center frequency of the feedforward amplifier is 2140 MHz with 60 MHz bandwidth. When the average output power of feedforward amplifier is 20 Watt. the intermodulation cancellation performance is more than 21 dB. In this case, the output power of feedforward amplifier reduced 3.5 dB because of extra delay line loss and coupling loss. The feedforward amplifier efficiency is more than 7.2 % for multicarrier signals, 59 dBc for ACPR.

• 전자공학회논문지A
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• 제31A권12호
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• pp.9-15
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• 1994

In this paper, the linearized power amplifier using digital adaptive predistorter is implemented in order to restrict spectral spreading and adjacent channel interference. The linearized systems is composed of a DSP56001 processor that executes predistortion in baseband. 90.deg. phase shifter, power splitter/combiner, quadrature modulator/demodulator of 360MHz band, and nonlinear amplifier. A ${\pi}$/4-shift QPSK is used to modulate digital random signals. As the quantized power of baseband signal and the output of amplifier are fed to the predistorter, and predistorting values are calculated using an adaptive algorithm. In the experiment, a peak to sidelobe ratio of the linearized amplifier is improved up to 15dB in comparison with conventional nonlinear amplifier, which means that the distortion of transmitted signal is decreased and adjacent channel interference was reduced.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.1176-1185
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• 2005

A linear power amplifier is particularly emphasized on the system using a linear modulations, such as 16QAM and QPSK with pulse shaping, because intermodulation distortion which causes adjacent channel interference and co-channel interference is mostly generated in a nonlinear power amplifier. In this paper, parameters of a linearization loop, such as an amplitude imbalance, a phase imbalance and a delay mismatch, are briefly analyzed to get a specific cancellation performance and linearization bandwidth. Experimental results are presented for IMT-2000 frequency band. The center frequency of the feedforward amplifier is 2140 MHz with 60 MHz bandwidth. When the average output power of feedforward amplifier is 20 Watt, the intermodulation cancellation performance is more than 21 dB. In this case, the output power of feedforward amplifier reduced 3.5 dB because of extra delay line loss and coupling loss. The feedforward amplifier efficiency is more than 7.2 % for multicarrier signals, 59 dBc for ACPR.

• 한국항해항만학회지
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• 제28권2호
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• pp.149-154
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• 2004

A linear power amplifier is particularly emphasized on the system using a linear modulations, such as 16QAM and QPSK with pulse shaping, because intermodulation distortion which causes adjacent channel interference and co-channel interference is mostly generated in a nonlinear power amplifier. In this paper, parameters of a linearization loop, such as an amplitude imbalance, a phase imbalance and a delay mismatch, are briefly analyzed to get a specific cancellation performance and linearization bandwidth Experimental results are presented for IMT-2000 frequency band The center frequency of the feedforward amplifier is 2140MHz with 60MHz bandwidth When the average output power of feedforward amplifier is 20 Watt, the intermodulation cancellation performance is more than 28dB. In this case, the output power of feedforward amplifier reduced 3.5dB because of extra delay line loss and coupling loss. The feedforward amplifier efficiency is more than 7% for multicarrier signals.

• 한국위성정보통신학회논문지
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• 제3권1호
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• pp.1-7
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• 2008

본 논문에서는 통신위성시스템 탑재를 위한 Ku-Band 선형화 채널증폭기 비행모델의 설계와 제작된 결과를 고찰하였다. 정착된 모든 서브모듈, 즉 가변이득증폭기, 가변전압감쇠기, 그리고 전치왜곡 보상회로를 위한 브랜치 라인 결합기와 검출기는 Thin-Film Hybrid 작업으로 제작되었다. 제작된 모듈의 성능은 초고주파 회로분석 시뮬레이션 툴과 우주환경에서의 전기적인 성능시험을 통하여 검증하였다.

• 대한의용생체공학회:의공학회지
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• 제17권2호
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• pp.179-188
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• 1996

A clinically oriented 32-channel electroencephalogram (EEG) and evoked potential (EP) mapping system has been developed EEG and EP signals acquired from 32-channel electrodes attached on the heroid surface are amplified by a pre-amplifier which is separated from main amplifier and is located near the patient to reduce signal attenuation and noise contamination between electrodes and the amplifier. The amplified signals are further amplified by a main amplifier where various filtering and gain contr61 are achieved An automatic artifact rejection scheme is employed using neural network-based EEG and artifact classifier, by which examination time is substantially reduce4 The continuously measured EEG sigrlals are used for spectral mapping, and auditory and visual evoked potentials measured in synchronous to the auditory and visual stimuli are used for temporal evoked potential mapping. A user-friendly graphical interface based on the Microsoft Window 3.1 is developed for the operation of the system. Statistical databases for comparisons of group and individual are included to support a statistically-based diagnosis.