• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.394-402
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• 2013

This paper presents design, fabrication and ruggedness test of switching-mode power amplifier using GaN(Gallium Nitride) HEMT(High Electron Mobility Transistor) for S-band radar applications. The power amplifier is designed to Class-F for high efficiency. The input signal for the measurement of the power amplifier is pulse signal at $100{\mu}s$ pulse width and duty cycle of 10 %. The measurement results of the fabricated Class-F power amplifier are a power gain of 10.8 dB, an output power of 40.8 dBm, a power added efficiency(PAE) of 54.2 %, and a drain efficiency of 62.6 %, at the center frequency. We proposed reliability test set-up of a power amplifier for ruggedness test. And we measured output power and efficiency according to VSWR(Voltage Standing Wave Ratio) variation. The designed power amplifier achieved output power of 32.6~41.1 dBm and drain efficiency of 23.4~63 % by changing VSWR, respectively.

• 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).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.4
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• pp.519-529
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• 1993

A spectral and power efficient modulation technique, named Compact Superposed Quadrature Amplitude Modulation (Compact-SQAM), is introduced. The performance of Compact-SQAM system, in a Linearly and nonlinearly amplified single and multicarrier environment, in the presence of additive white Gaussian noise(AWGN), intersymbol interference(ISI), timing jitter and adjacent channel interference (ACI), is experimentally analyzed via computer simulation. Various channel conditions, such as channel spacing, between the main and adjacent channels and fade depth on the desired main channel, are examined. Our result shows that Compact-SQAM, and better P(e) performance that other modems using simple Butteroworth type postdetection receive filters. Especially, Compact-SQAM modem achieves higher efficiency of frequency utilization and better P(e) performance than other modems in the severly bandlimited nonlinear multicarrier channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8B
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• pp.1251-1258
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• 2010

Major utilities have been focusing on R&D and business of AMI system which plays a vital role in SmartGrid whose concept is to optimize energy efficiency with exchanging real time information between utilities and consumers based on IT technologies in power grid. In this paper, we introduce KEPCO's AMI business plan, the AMI System architecture, designed core devices, communication networks and value added services, and also explore technical and business characteristics of KEPCO's AMI system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.53-61
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• 2014

In this paper, we present the design, fabrication and measurement of high efficiency GaN HEMT power amplifier using harmonic matching technique. In order to achieve high efficiency, harmonic load-pull simulation is performed, that is, the optimum load impedances are determined at $2^{nd}$ and $3^{rd}$ harmonic frequencies as well as at the fundamental. Then, the output matching circuit is designed based on harmonic load-pull simulation. The measurement of the fabricated power amplifier shows the linear gain of 20 dB and $P_{1dB}$(1 dB gain compression point) of 33.7 dBm at 1.85 GHz. The maximum power added efficiency(PAE) of 80.9 % is achieved at the output power of 38.6 dBm, which belongs to best efficiency performance among the reported high efficiency power amplifiers. For W-CDMA input signal, the power amplifier shows a PAE of 27.8 % at the average output power of 28.4 dBm, where an ACLR (Adjacent Channel Leakage Ratio) is measured to be -38.8 dBc. Digital predistortion using polynomial fitting was implemented to linearize the power amplifiers, which allowed about 6.2 dB improvement of an ACLR performance.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.05a
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• pp.131-134
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• 2020

기존의 중앙 집중형 에너지 거래 방식을 블록체인 기반의 분산형 거래방식으로 변경하여 누구나 공급자나 수요자(프로슈머)가 될 수 있고, 투명하고 신뢰성 있는 에너지 거래가 이루어지도록 한다. 이러한 거래가 이루어지기 위해 공급자와 수요자를 연결하고 공급 및 수요를 효율적으로 관리하여 새로운 부가가치를 창출하는 시스템을 개발한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.92-97
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• 2007

Switching mode amplifiers have been studied widely for use at microwave frequency range, and the class E amplifier which is a type of switching mode amplifier offers very high efficiency approaching 100%. In this paper, 2.4GHz microwave class E amplifier with 66% power added efficiency (PAE) and 17.6dBm output has been linearized for use at wireless LAN transmitter, and digital predistortion technique with look up table is applied. With -3dBm input power of wireless LAN, measured output spectrum can meet the required IEEE 802.11g standard spectrum mask, and the digital predistortion output spectrum has been improved by 5dB of ACPR at 20MHz offset from center frequency.

• Journal of IKEEE
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• v.1 no.1 s.1
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• pp.164-175
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• 1997

In this paper, the CE-OQPSK that has constant envelope was designed for applying PSK to the nonlinear amplifier so as to improve power efficiency. For this realization. ROM and D/A converter that have relative low power consumption were used. As a result of comparing the PSD (Power spectrum density) of CE-OQPSK with that of conventional OQPSK through simulation for estimating the performance. In case of correlation factor ${\alpha}$ = 0.707. the improvement of bandwidth efficiency of 5% and 20% is achieved in the main lobe and the sidelobe, respectively. And, in case additional bandwidth-limiting-filter is added, it can be shown that the PSD of CE-OQPSK meet the FCC wireless LAN spectrum specification.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.766-772
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• 2018

A 6~10 GHz wide-band power amplifier was designed using an InGaAs enhancement-mode(E-mode) $0.15{\mu}m$ pseudomorphic high-electron-mobility transistor(pHEMT). The positive gate bias of the E-mode pHEMT device removes the need for complex negative voltage generation circuits, therefore reducing the module size. The wire bond and substrate loss parameters were modeled and extracted using a three-dimensional electromagnetic(3D EM) simulation. For wideband characteristics, lossy matching was adopted and the gate bias was optimized for maximum power and efficiency. The measured gain, in/output return loss, output power, and power-added efficiency were greater than 20 dB, 8 dB, 27 dBm, and 35 %, respectively, in the 6~10 GHz band.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.849-854
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• 2023

In this paper, a high-efficiency power amplifier was designed by applying the operating point Class J using LDMOS(laterally diffused metal oxide semiconductor) and optimizing the output matching circuit so that the second harmonic impedance becomes the reactance impedance. The designed power amplifier has a frequency of 108 ~ 110 MHz, Characteristics of PAE(power added efficiency) is 71.5% at P_SAT output (54.5 dBm), 55.5% at P_1dB output (51.5 dBm), and 24.38% at 45 dBm. The CSB(carrier with sideband) amplifier, which is the reference signal in the spatial modulation method, has an operating output of 45 dBm ~ 35 dBm, and linear SDM(sum in the depth of modulation) characteristics(40% ± 0.3%) were obtained. We measure the characteristics in amplitude modulation according to the bias operating point of the power amplifier for CSB and propose the optimal operating point to obtain linear modulation characteristics.