• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.897-900
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• 2005

RF linearity of double-gate MOSFETs is investigated using accurate two-dimensional simulations. The linearity has been analyzed using the Talyor series. Transconductance is dominant nonlinear source of CMOS. It is shown that DGMOSFET linearity can be improved by a careful optimization of channel thickness, gate oxide thickness, gate length, overlap length and channel doping concentration. The minimum $P_{IP3}$ data are compared in each case. It is shown that DG-MOSFET linearity can be improved by a careful optimization of channel thickness, gate oxide thickness, gate length, overlap length and channel doping concentration..

• Journal of the Optical Society of Korea
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• v.12 no.4
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• pp.303-308
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• 2008

Directly modulated fiber-optic links generally suffer higher link loss and larger signal distortion than externally modulated links. These result from the electron-photon conversion loss and laser modulation dynamics. As a method to overcome the drawbacks, we have experimentally demonstrated the RF performance of directly modulated, ultra-strong injection-locked gain-lever distributed Bragg reflector (DBR) lasers. The free-running DBR lasers exhibit an improved amplitude modulation efficiency of 12.4 dB under gain-lever modulation at the expense of linearity. By combining gain-lever modulation with ultra-strong optical injection locking, we can gain the benefits of both improved modulation efficiency from the gain-lever effect, plus improved linearity from injection locking. Using an injection ratio of R=11 dB, a 23.4-dB improvement in amplitude response and an 18-dB improvement in spurious-free dynamic range have been achieved.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.1
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• pp.72-79
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• 1997

Most open magnetic resonance imaging systems have used the planar gradient coils whose inductances were minimized through the magnetic energy minimization procedure in the spatial frequency domain. Though the planar gradient coils have smaller inductance than conventional gradient coils, the planar gradient coils often suffer from their poor magnetic field linearity. Scaling the spatial frequencies of the current density function designed by the magnetic energy minimization, magnetic field linearity of the planar gradient coils can be greatly improved with small sacrifice of gradient coil inductance. We have found that the figure of merit of the planar gradient coils, defined by the gradient strength divided by the linearity error and the inductance, can be improved by proposed technique.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.2
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• pp.75-82
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• 2009

This paper proposes a method which increases the linearity using an improvement mechanism of Doherty power amplifier and compensates the decrement of efficiency due to improvement of linearity. To verify the method, a 20W power amplifier is designed and implemented. Compared with 2-way Doherty power amplifier, the implemented 3-way Doherty power amplifier with class F shows improved linearity about 10dBc and efficiency about 1.5%. Also, efficiency characteristic has been improved about 3.5% compared with the 2-way Doherty power amplifier while maintaining linearity. This results show that the proposed 3-way Doherty power amplifier with class F is shown to be adequate for improvement of efficiency and linearity. It is expected that the proposed amplifier can be used for various wireless communication system amplifiers.

• 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 Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.43-46
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• 2001

The ZnO devices using semiconductor properties, to include $MnO_2$, $Y_2O_3$ and other material, was fabricated by $Sb_2O_3$ mol ratio from 1 to 4 [mol%]. The non-linearity factor was calculated by setting current to be $1[mA/cm^2]$ and $10[mA/cm^2]$. The spinel structure was fonned by $Sb_2O_3$ addition and it was depressed the ZnO grain formation. The grain growing was controlled by spinel structure that has improved the non-linearity factors. The breakdown voltage characteristics of semiconductor devices to increase with $Sb_2O_3$ was increased in voltage-current. The non-linearity value of ZnO semiconductor devices was 45 over.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.2
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• pp.80-85
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• 2010

In this paper, the efficiency of power amplifier has been maximized by the application of EER structure, and the linearity has been improved by using metamaterial structure. This paper has proposed a design of power amplifier in class-F to get the PAE, and to control dynamic power using envelope detector. CRLH structure gets high-linearity by removing harmonics arisen from the mismatching of matching circuit. The PAE and the 3rd order IMD have been improved 5.93 %, 12.83 dB compared with those of conventional Class-F amplifier, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.6 s.121
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• pp.584-590
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• 2007

In this paper, the efficiency of power amplifier has been maximized by the application of EER structure, and the linearity has been improved by using PBG structure. This paper has proposed a design of power amplifier in class-F to get the PAE, and to control dynamic power using envelope detector. PBG structure gets high-linearity by removing harmonics arisen from the mismatching of matching circuit. The PAE and the 3rd order IMD have been improved 34.64%, 6.65 dB compared with those of conventional Doherty amplifier, respectively.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.443-447
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• 1999

The AC drive systems of a voltage source inverter and an induction motor. The inverter non linearity caused by the turn on/off time dependency of the current level in the switching IGBT is described in the first part of this paper. To improve the low-speed drive characteristics, accurate applied voltage calculation is proposed under considerations of the compensations for the quantization error in the digital controller, the forward voltage drop of switching drives and the dead time of the inverter. The experimental studies show the improved drive characteristics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.807-813
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• 2008

The gate-biases of the Doherty power amplifier are controlled to improve the linearity performance. The linearity improvement mechanism of the Doherty amplifier is the harmonic cancellation of the carrier and peaking amplifier at the output power combining point. However, it is difficult to cancel the harmonic power for the broader power range because the condition for cancelling is varied by power. For the linearity improvement, we have explored the linearity characteristic of the Doherty amplifier according to the input power and gate biases of the carrier and peaking amplifier. To extend the region of harmonic power cancellation, we have injected the proper gate bias to the carrier and peaking amplifier according to the input power levels. To validate the linearity improvement, the Doherty amplifier is designed using Eudyna 10-W PEP GaN HEMT EGN010MKs at 2.345 GHz and optimized to achieve a high linearity and efficiency at an average output power of 33 dBm, backed off about 10 dB from the $P_{1dB}$. In the experiments, the envelope tracking Doherty amplifier delivers a significantly improved adjacent channel leakage ratio performance of -37.4 dBc, which is an enhancement of about 2.8 dB, maintaining the high PAE of about 26 % for the WCDMA 1-FA signal at an average output power of 33 dBm. For the 802.16-2004 signal, the amplifier is also improved by about 2 dB, -35 dB.