• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.337-340
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• 2000

In this paper, I compared some characteristics between HPA and LPA using Feedforward method. Feedforward method is known for best IMD correction. HPA generated 46.5㏈c at 45.5㏈m output power. But, using feedforward linearing method, I could improve IMD to 67.17㏈c at the same output power. IMD could be improved 20.67㏈ at 45.5㏈m output power. I measured average power, IMD, total current, and efficiency of two amplifier at many different power levels. I could get about 70d3c IMD using feedforward method.

• 대한전자공학회논문지TC
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• 제39권6호
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• pp.27-27
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• 2002

본 논문에서는 새로운 방식의 아날로그Feedforward 선형화기 시스템을 이용하여 IMT-2000주파수 대역(2110∼2170 MHz)에서 동작하는 평균 출력전력 30W급의 선형증폭기를 설계 및 제작하였다. 새로운 방식의 아날로그 Feedforward 방식의 회로는 크기가 작고, 회로 동작이 단순하여 안정된 동작을 수행하였다. 제작된 선형증폭기는 2110∼2170MHz 대역 중에서 2-tone 신호를 입력할 경우에 주파수 대역에 따른 별도의 회로 수정없이 60dBc 이상의 혼변조 신호 감쇄를 가졌다. 이는 주전력증폭기의 동일한 출력대비 23dB 이상의 혼변조 신호 감쇠 효과를 갖는 것이다.

• 대한전자공학회논문지TC
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• 제39권6호
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• pp.285-291
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• 2002

본 논문에서는 새로운 방식의 아날로그Feedforward 선형화기 시스템을 이용하여 IMT-2000주파수 대역(2110∼2170 MHz)에서 동작하는 평균 출력전력 30W급의 선형증폭기를 설계 및 제작하였다. 새로운 방식의 아날로그 Feedforward 방식의 회로는 크기가 작고, 회로 동작이 단순하여 안정된 동작을 수행하였다. 제작된 선형증폭기는 2110∼2170MHz 대역 중에서 2-tone 신호를 입력할 경우에 주파수 대역에 따른 별도의 회로 수정없이 60dBc 이상의 혼변조 신호 감쇄를 가졌다. 이는 주전력증폭기의 동일한 출력대비 23dB 이상의 혼변조 신호 감쇠 효과를 갖는 것이다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.345-348
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• 2000

In this paper, A Feedforward Linear Power Amplifier for IMT-2000 which IMD characteristics was improved was designed and fabricated. To improve the main power amplifier IMD characteristics, the Feedback loop was added to basic Feedforward Power Amplifier structure. Therefore, the output power of error amplifier can be reduced, and it is easy to control the linearization circuit to cancel total IMD. The designed power amplifier represented the 40㏈m(l0W) output power and -55㏈C 3rd IMD at Center frequency 2.14㎓ (@5㎒).

• 한국전자파학회논문지
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• 제18권11호
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• pp.1262-1270
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• 2007

본 논문에서는 feedforward와 post-distortion 기법을 이용하여 평형 증폭기 내에서 발생하는 혼변조 왜곡 성분을 제거할 수 있는 새로운 왜곡 상쇄 메커니즘인 cross post-distortion 선형화 기법을 제안한다. 출력 동적 영역과 대역폭 측면에서 제안하는 선형화 방식은 기존의 feedforward 방식에 뒤지지 않는 성능을 가지고 있으면서 상대적으로 높은 효율을 제공한다. 이론적 뒷받침을 위해 제안하는 시스템과 feedforward 방식의 전력 증폭기와 오차증폭기의 전력 용량을 비교 분석하였고, IMT-2000 대역에서 실제 구현을 통하여 이를 실험적으로 뒷받침하였다. 최대 출력 전력 240 W의 기지국용 상용 대전력 증폭기에 적용했을 때, wideband code division multiple access (WCDMA) 4FA 신호에 대하여 평균 출력 전력 40 dBm에서 약 18.6 dB의 개선 효과를 얻었다. 제작된 전력 증폭기는 WCDMA 신호 기준으로 feedforward 방식에 비해 약 2 % 개선된 효율을 보였다.

• 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.

• Journal of Power Electronics
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• 제11권2호
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• pp.211-217
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• 2011

The dynamic response of a multi-MW wind turbine to a sudden change in wind speed is usually slow, because of the slow pitch control system. This could cause a large excursion of the rotor speed and an output power over the rated. A feedforward pitch control can be applied to minimize the fluctuations of these parameters. This paper introduces the complete design steps for a feedforward pitch controller, which consist of three stages, i.e. the aerodynamic torque estimation, the 3-dimensional lookup table for the wind seed estimation, and the calculation of the feedforward pitch amount. The effectiveness of the feedforward control is verified through numerical simulations of a multi-MW wind turbine.

• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.744-747
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• 1991

In this paper, the design of optimal feedforward regulators with the optimal feedforward filters for improving power frequency deviations in an interconnected system, using a polynominal LQG approach, is proposed. The performances of the regulators with the optimal feedforward filters were compared with the frequency feedback regulator only in power system by simulation. The results show that the optimal feedforward regulators reduce the power frequency standard deviation by 25%-60% in the white noise load and the peak deviation in the step load by 8%-27%.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2000년도 종합학술발표회 논문집 Vol.10 No.1
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• pp.187-190
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• 2000

In this paper, A Feedforward Linear Power Amplifier which is appended a feedback loop for IMT-2000 was designed and fabricated. Feedback loop was used to improve the IMD(Inter-Modulation Distortion) characteristics of the main amplifier. And it is easy to cancel IMD on the min path and control IMD cancellation loop, compared with basic Feedforward Linear Power Amplifier. This feedback loop has the same effect of the Predistroter. So, This power amplifier was improved in IMD characteristics to add the effect of Predistroter to basic Feedforward amplifier. And the disigned power amplifier in this paper represented the 40dBm(10W) output and -55dBc 3rd IMD at center frequency 2.14GHz (@10MHz).