• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.1934-1939
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• 2006

Current digital communication system is selecting very various digital Modulation way. Need linear power amplifier necessarily to reduce interference for contiguity channel maximum in this communication system and at the same time, power amplifier of high efficiency is required. In this paper Compare with result of equilibrium power amplifier that design Doherty power amplifier of way that linearity and efficiency are improved at the same time through simulation optimization techniques and at the same time design through simulation, efficiency 20% linearity showed 10dB that is improved.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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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).

• ETRI Journal
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• v.29 no.4
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• pp.536-538
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• 2007

We propose and describe the fabrication of a linear power amplifier (LPA) using a new analog feedforward method for the IMT-2000 frequency band (2,110-2,170 MHz). The proposed analog feedforward circuit, which operates without a pilot tone or a microprocessor, is a small and simple structure. When the output power of the fabricated LPA is about 44 dBm for a two-tone input signal in the IMT-2000 frequency band, the magnitude of the intermodulation signals is below -60 dBc and the power efficiency is about 7%. In comparison to the fabricated main amplifier, the magnitude of the third intermodulation signal decreases over 24 dB in the IMT-2000 frequency band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.11
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• pp.1262-1270
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• 2007

In this paper, we propose a new distortion cancellation mechanism for a balanced power amplifier structure using the carrier cancellation loop of a feedforward and post-distortion technique. The proposed cross post-distortion balanced linear amplifier can reduce nonlinear components as much as the conventional feedforward amplifier through the output dynamic range and broad bandwidth. Also the proposed system provides higher efficiency than the feedforward. The capacities of power amplifier and error power amplifier in the proposed system are analyzed and compared with those of feedforward amplifier. Also the operation mechanisms of the three kind loops are explained. The proposed cross post-distortion balanced linear power amplifier is implemented at the IMT-2000($f_0=2.14\;GHz$) band. With the commercial high power amplifiers of total power of 240 W peak envelope power fer base-station application, the adjacent channel leakage ratio measurement with wideband code division multiple access 4FA signal shows 18.6 dB improvement at an average output power of 40 dBm. The efficiency of fabricated amplifier Improves about 2 % than the conventional feedforward amplifier.

• Proceedings of the IEEK Conference
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• 2000.11a
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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㎒).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.6
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• pp.27-27
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• 2002

In this paper, the LPA(Linear Power Amplifier) using new analog feedforward linearizer for IMT-2000 frequency band(2110MHz∼2170MHz) is proposed and fabricated. The designed analog feedforward linearizer system possessing the characteristics of stable operation for input power variation is simple structure and small size. When two-tones in IMT-2000 frequency band are applied to an amplifier, this LPA have the average output power is about 30W and the IMD value is below about 60dBc without correcting the circuit. In camparision with an amplifier without feedforward system at the same output power, the supposed analog feedforward linear amplifier posseses improved the IMD characteristics of over 23dB.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.6
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• pp.285-291
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• 2002

In this paper, the LPA(Linear Power Amplifier) using new analog feedforward linearizer for IMT-2000 frequency band(2110MHz∼2170MHz) is proposed and fabricated. The designed analog feedforward linearizer system possessing the characteristics of stable operation for input power variation is simple structure and small size. When two-tones in IMT-2000 frequency band are applied to an amplifier, this LPA have the average output power is about 30W and the IMD value is below about 60dBc without correcting the circuit. In camparision with an amplifier without feedforward system at the same output power, the supposed analog feedforward linear amplifier posseses improved the IMD characteristics of over 23dB.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.4
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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.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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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.

• Journal of Navigation and Port Research
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• v.28 no.2
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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.