• Journal of Navigation and Port Research
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• v.27 no.2
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• pp.217-221
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• 2003

In this work, we used a novel RF-CSP to develop a broadband amplifier MMIC, including all the matching and biasing components, for Ku and K band applications. By utilizing an ACF for the RF-CSP, the fabrication process for the packaged amplifier MMIC could be simplified and made cost effective. STO (SrTiO$_3$) capacitors were employed to integrate the DC biasing components on the MMIC. A pre-matching technique was used for the gate input and drain output of the FETs to achieve a broadband design for the amplifier MMIC. The amplifier CSP MMIC exhibited good RF performance (Gain of 12.5$\pm$1.5 dB, return loss less than -6 dB, PldB of 18.5$\pm$1.5 dBm) over a wide frequency range. This work is the first report of a fully integrated CSP amplifier MMIC successfully operating in the Ku/K band.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.589-592
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• 2002

A CMOS power amplifier for IMT-2000 is designed with 0.25-${\mu}m$ CMOS technology. This amplifier circuits consist of two cascode stages. Used cascode structure has good reverse isolation. These amplifier circuits consist of two stages which are driver stage and power amplification stage. The designed power amplifier is simulated with ADS using 0.25-${\mu}m$ CMOS library at 3.3 V power supply. Simulation results indicate that the amplifier has a PAE of 39 % and power gain of 24 dBm at 1.95 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.1
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• pp.1-11
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• 2009

In this paper, a new 1 kW power amplifier with high efficiency and high stability in a RF generator is designed and fabricated for plasma applications. The efficiency of power amplifier is improved by using class-E amplifier that consists of one push-pull MOSFET and high current drive IC instead of class-C amplifier composed of several single ended MOSFET. Switchable damper that allows selecting three different modes of amplifiers for considering efficiency and stability is added into the amplifier for plasma applications. Stable region of an early electronic discharge section is extended to VSWR of 4.5:1 compared to conventional VSWR of 3.8:1 through using switchable damper. The dimension of the amplifier is also reduced to 30 % of conventional amplifier. The 80 % efficiency of power amplifier with switchable damper is obtained the output power of 1 kW in operating frequency of 13.56 MHz. In comparison of conventional power amplifier for plasma applications, 13 % efficiency is improved.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.15-29
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• 2002

MRI에서 펄스 시퀀스(pulse sequence)란 고주파 RF(radiofrequency) 펄스 및 경사자장(gradient) 펄스를 가하고 MR 신호를 획득하는 순서를 시간대별로 도식화 한 pulse diagram을 이야기한다. 이러한 pulse sequence는 실제로 영상을 획득하기 위한 RF amplifier, gradient amplifier 등의 하드웨어를 순차적(sequential)으로 구동하는 역할을 한다. 따라서 이러한 pulse sequence는 현재 임상적으로 사용되는 다양한 영상기법들을 이해하는데 필수적이다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.1-9
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• 2017

In this paper, ETRI's $0.25{\mu}m$ GaN MMIC process is introduced and the fabricated results of X-Band 3 W power amplifier MMIC are discussed. The one-stage X-Band 3 W power amplifier MMIC using the $0.25{\mu}m$ GaN MMIC devices has been designed and fabricated. From the fabricated GaN MMIC, the characteristics of the $0.25{\mu}m$ GaN MMIC process and devices are evaluated and analyzed. The X-band power amplifier MMIC shows output power of 3.5 W, gain of 10 dB, and power-added efficiency of 35 %.

• Journal of Navigation and Port Research
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• v.27 no.2
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• pp.209-215
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• 2003

In this paper. We tested and fabricated the error amplifier for the 15 Watt linear power amplifier for the IMT-2000 baseband station. The error amplifier was comprised of subtractor for detecting intermodulation distortion, variable attenuator for control amplitude, variable phase shifter for control phase, low power amplifier and high power amplifier. This component was designed on the RO4350 substrate and integrated the aluminum case with active biasing circuit. For suppression of spurious, the through capacitance was used. The characteristics of error amplifier measured up to 45 dB gain, $\pm$0.66 dB gain flatness and -15 dB input return loss. Results of application to the 15 Watt feedforward Linear Power Amplifier, the error amplifier improved with 27 dB cancellation from 34 dBc to 61 dBc IM$_3$.

• Journal of Advanced Navigation Technology
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• v.20 no.6
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• pp.556-561
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• 2016

This paper describes implementation of a 13.56 MHz, 5 kW RF high power generator for ISM band applications. This RF generator consists of four LDMOS modules of 1.25kW class-AB push-pull power amplifier with drive amplifier and its outputs are combined by using Wilkinson type transmission-line transformers. Its generator has a high efficiency and output power better than linearity. In order to discharge power transistor heats, we used on water cooled copper plate. Also, these have a composite circuit of combiner and low-pass filter and safety circuit to detector over and reflected power. The RF generator has achieved a efficiency of 79 % at 5.33 kW of saturated power level experimentally.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.114-121
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• 2003

In this paper, low voltage and two stage CMOS Class E RF power amplifier for ISM(Industrial/Scientific/Medical) Open Band is presented. The power amplifier operates at 2.4GHz frequency, and is designed and simulated with a 0.35um CMOS technology and HSPICE simulator. The power amplifier is simple structure of two stage Class E power amplifier. The design procedure determing matching network was presented. The power amplifier is composed of input stage matching network, preamplifier, interstage matching network, power amplifier, and output stage matching network. The matching networks of input stage and interstage were constituted by pi($\pi$) type and L type respectively. At 2.4GHz operating frequency, and with a 2.5V supply voltage, the power amplifier delivers 23dBm output power to a 50${\Omega}$ load with 39% power added efficiency(PAE).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.83-88
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• 2007

The reliability characteristics of class-E RF power amplifier are studied, based on the degradation of MOSFET electrical characteristics. The class-E power amplifier operates as a switch mode operation to achieve high efficiency. This operation leads to high voltage stress when MOSFET switch is turned-off. The increase in threshold voltage and decrease in nobility caused by high voltage stress leads to a drop in the drain current. In the class-E power amplifier the effects caused by the degradation of MOSFET drain current is a drop of the power efficiency and output power. But the small inductor in the class-E load network allows the reliability to be improved. After $10^{7}\;sec$. the drain current decreases 46.3% and the PAE(Power Added Efficiency) decreases from 58% to 36% when the load inductor is 1mH. But when the load inductor is 1nH the drain current decreases 8.89% and the PAE decreases from 59% to 55%.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.113-117
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• 2003

This paper describes the design and the simulation results of the RF CMOS Class-E Power Amplifier for a 2.4GHz ISM band. This circuit is composed two connected amplifiers. where Class F amplifier drives Class E amplifier. The proposed circuit can reduce the total power dissipation of the driving stage and can work with higher efficiency. The power amplifier has been implemented in a standard $0.25{\mu}m$ CMOS technology and is shown to deliver 100mW output power to load with 41% power added efficiency(PAE) from a 2.5V supply.