• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.12
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• pp.41-46
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• 2008

We report a high gain D-band(110 - 140 GHz) MMIC drive amplifier based on $0.1{\mu}m$ InGaAs/InAlAs/GaAs metamorphic HEMT technology. The amplifier shows an excellent $S_{21}$ gain characteristic greater than 10 dB in a millimeterwave frequency of 110 GHz, Also the amplifier has good reflection characteristics of a $S_{11}$ of -3.5 dB and a $S_{22}$ of -6.5 dB at 110 GHz, respectively The high performances of the MMIC drive amplifier is mainly attributed to the characteristics of the MHEMTs exhibiting a maximum transconductance of 760 mS/mm, a current gain cut-off frequency of 195 GHz and a maximum oscillation frequency of 391 GHz.

• ETRI Journal
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• v.29 no.1
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• pp.89-94
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• 2007

A mathematical model for the input-output characteristic of an amplifier exhibiting gain expansion and weak and strong nonlinearities is presented. The model, basically a Fourier-series function, can yield closed-form series expressions for the amplitudes of the output components resulting from multisinusoidal input signals to the amplifier. The special case of an equal-amplitude two-tone input signal is considered in detail. The results show that unless the input signal can drive the amplifier into its nonlinear region, no gain expansion or minimum intermodulation performance can be achieved. For sufficiently large input amplitudes that can drive the amplifier into its nonlinear region, gain expansion and minimum intermodulation performance can be achieved. The input amplitudes at which these phenomena are observed are strongly dependent on the amplifier characteristics.

• Journal of Drive and Control
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• v.10 no.4
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• pp.22-28
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• 2013

Mechanical and electrical properties of a DDV(Direct Drive servo Valve) with electric feedback are analysed via reverse analysis technique in this work. The DDV is disassembled and mechanical parameters, such as spool mass, spring stiffness and port size are identified. The servo amplifier, which is built in the valve, is reversely analysed and the control scheme and gains for several control actions are also identified. The electrical feedback for spool displacement improves much better the valve performance, such as hysteresis and dynamic bandwidth frequency, than an ordinary mechanical feedback valve. Integrating control action with very large gain was adopted in the valve amplifier, and it seemed to give high performance.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.1
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• pp.63-69
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• 2010

In this paper, a new design method of asymmetrical configuration of main amplifier and peaking amplifier using changed bias point is proposed for excellent linearity, instead of the conventional Doherty structure. We have utilized the uneven wilkinson power divider for the unequal power drive at the input network of amplifiers. And we proposed a compensating method of the decreasing efficiency due to improving linearity using 3-stage Doherty structures. From the simulation results of asymmetrical Dohertry power amplifier and asymmetrical 3-stage Doherty power amplifier with uneven power drive are implemented. From the implementation and measurement results of the each amplifier, IMD characteristics have -55 dBc as the good efficiency of 13% compensates the decreased entire efficiency due to the improving linearity characteristics.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.1-7
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• 2021

In this paper, by embedding a bare-die chip-type drive amplifier into the PCB composed of ABF and FR-4, it implements an embedded active device that can be applied in 28 GHz band modules. The ABF has a dielectric constant of 3.2 and a dielectric loss of 0.016. The FR-4 where the drive amplifier is embedded has a dielectric constant of 3.5 and a dielectric loss of 0.02. The proposed embedded module is processed into two structures, and S-parameter properties are confirmed with measurements. The two process structures are an embedding structure of face-up and an embedding structure of face-down. The fabricated module is measured on a designed test board using Taconic's TLY-5A(dielectric constant : 2.17, dielectric loss : 0.0002). The PCB which embedded into the face-down expected better gain performance due to shorter interconnection-line from the RF pad of the Bear-die chip to the pattern of formed layer. But it is verified that the ground at the bottom of the bear-die chip is grounded Through via, resulting in an oscillation. On the other hand, the face-up structure has a stable gain characteristic of more than 10 dB from 25 GHz to 30 GHz, with a gain of 12.32 dB at the center frequency of 28 GHz. The output characteristics of module embedded into the face-up structure are measured using signal generator and spectrum analyzer. When the input power (P_in) of the signal generator was applied from -10 dBm to 20 dBm, the gain compression point (P_1dB) of the embedded module was 20.38 dB. Ultimately, the bare-die chip used in this paper was verified through measurement that the oscillation is improved according to the grounding methods when embedding in a PCB. Thus, the module embedded into the face-up structure will be able to be properly used for communication modules in millimeter wave bands.

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.154-157
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• 2008

A class-E RF(Radio Frequency) power amplifier for wireless application is designed using standard CMOS technology. To drive the class-E power amplifier, a class-F RF power amplifier is used and the reliability characteristics are studied with a class-E load network. The reliability characteristic is improved when a finite-DC feed inductor is used instead of an RF choke with the load. After one year of operating, when the load is an RF choke the output current and voltage of the power amplifier decrease about 17% compared to initial values. But when the load is a finite DC-feed inductor the output current and voltage decrease 9.7%. The S-parameter such as input reflection coefficient(S11) and the forward transmission scattering parameter(S21) is simulated with the stress time. In a finite DC-feed inductor the characteristics of S-parameter are changed slightly compared to an RF-choke inductor. From the simulation results, the class-E power amplifier with a finite DC-feed inductor shows superior reliability characteristics compared to power amplifier using an RF choke.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.326-329
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• 2003

In this paper, we designed and implemented a high power amplifier(HPA) to achieve the high Power Added Efficiency(PAE) over 40% at the 90W output power for the ISM-band(fo=2.45GHz). HPA presented in this paper has 3-stage drive amplifier and 1-stage final amplifier. In the final amplifier, we utilized balanced amplifier configuration with GaAs FET and each of two amplifiers has the push-pull configuration to increase PAE. From the measurement results, we obtained PAE of 42.95% at the 90.57W output power.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.6
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• pp.287-290
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• 2006

A class-E CMOS RF(Radio frequency) power amplifier with a 1.8 Volt power supply is designed using $0.25{\mu}m$ standard CMOS technology. To drive the class-E power amplifier, a Class-F RF power amplifier is used and the reliability characteristics are studied with a class-E load network. After one year of operating the power amplifier with an RF choke, the PAE(Power Added Efficiency) decreases from 60% to 47% and the output power decreases 29%. However, when a finite DC-feed inductor is used with the load, the PAE decreases from 60% to 53% and the output power decreases only 19%. The simulated results demonstrate that the class-E power amplifier with a finite DC-feed inductor exhibits superior reliability characteristics.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.499-502
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• 2004

A two-stage Class E power amplifier operated at 2.44GHz is designed in 0.25-$\mu$m CMOS process for Class-l Bluetooth application. The power amplifier employs c1ass-E topology to exploit its soft-switching property for high efficiency. A preamplifter with common-mode configuration is used to drive the output-stage of Class-E type. The amplifier delivers 20-dBm output power with 70$\%$ PAE (power -added-efficiency) at 2-V supply voltage.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.1001-1002
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• 2006

As most of the powerline modems use spread spectrum modulation method which has strong immunity against the narrowband fading, or psk modulation method, the amplitude of the signal contains no useful informations. In this paper, we used class D amplifier to implement the drive circuit of the analog front end, and showed that it has great superiority over other existing drive circuits in rapidly impedance changing power line channel.