• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.2
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• pp.61-66
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• 2011

A new via structure on printed circuit board has been proposed for differential signaling in applications of high-speed interconnection. In new structure, the via is physically separated and then divided into two electrically-isolated sections using mechanical drill routing process. These cutted vias are connected respectively to the traces of the differential pair. New via structure makes possible to rout the differential pair using only one via, while conventional via structure needs two vias for interconnection. Because the spacing even in via region keeps almost constant, new via structure can alleviate an impedance discontinuity and then enhance its signal transmission characteristics such as reflection loss and insertion loss. It is expected that new via structure is effective in differential signaling for high-speed interconnection.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.116
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• pp.15-23
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• 2007

A simple six-port direct conversion QPSK receiver which is made up of a six-port phase correlator, a signal power detector, and I/Q channel signal de-modulator is designed and implemented in this paper. The output phase signals of six-port phase correlator are also analysed. On the basis of $90^{\circ}C$ phase relation among the six-port phase correlator output signals, the QPSK de-modulation circuit is designed by a simple circuit. The six-port phase correlator is made up of $90^{\circ}$ hybrid branch line and power detector. The six-port phase correlator, which is designed in frequency range of 11.7 to 12.0 GHz, gets the phase error characteristics less than $5^{\circ}$. By considering matching network and amplitude balance in the designed fiequency range, the designed six-port direct conversion QPSK receiver demodulates the I and Q signals with performance less than $5^{\circ}$ phase error.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.6
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• pp.646-652
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• 2014

This paper presents a design and fabrication of Ku-band power amplifier using Gallium Nitride High Electron Mobility Transistor (GaN HEMT) die. In order to fabricate the low-cost Ku-band power amplifier, a Printed Circuit Board(PCB) was used for input/output matching circuits instead of manufacturing process to use an expensive substrate. The measured output power is 42.6 dBm, the drain efficiency is 37.7 % and the linear gain is 7.9 dB under pulse operation at the frequency of 14.8 GHz. Under the continuous wave(CW) test, the output power is 39.8 dBm, the drain efficiency is 24.1 % and the linear gain is 7.2 dB.

• Journal of Satellite, Information and Communications
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• v.12 no.2
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• pp.89-93
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• 2017

This paper introduces an energy harvesting system that generates energy by collecting multi-band RF signals using buck-boost DC-DC converter. In an environment where the resistance of load using the collected electric energy is constantly changing, a buck-boost DC-DC converter is used in which the input resistance of the DC-DC converter does not change even if the load resistance changes. Since the frequency band of the input RF signal varies, the rectifier is designed for each band so that multiple bands can be processed, and a matching circuit is added to each band in front of the rectifier. For a rectifier to collect very small RF signals, a circuit is designed so that a constant voltage is obtained according to a very small input signal by devising a method of continuously accumulating the voltages collected and generated in each band. It is confirmed that the output efficiency can reach up to 20% even for the RF signal having the input of -20 dBm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.6
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• pp.141-147
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• 2008

This paper describes the design of frequency down converting Mixer in the receiver to use compound semiconductor and CMOS product process. The basic theory and structure of frequency down converting Mixer is surveyed, and we design mixer circuit with active balun which use the compound semiconductor and CMOS process. This mixer convert a single ended signal to differential signal at input port of RF and LO instead of matching circuit to get dual band balanced mixer structure and characteristic broadband. This designed mixer has a conversion gain $-1{\sim}-6[dB]$ at $2{\sim}6[GHz]$ bandwidths. However, the simulation of the designed mixer with active balun has the result of a 7[dB] conversion gain for -2[dBm] LO input power and -10[dBm] input P1[dB] at 5.8[GHz].

• Journal of Advanced Navigation Technology
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• v.6 no.4
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• pp.279-290
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• 2002

In this paper, tapered shape of multiport power divider/combiner modified for 2 GHz range from the model published by [10] is proposed. Parameters determining electrical property of the circuit structure have been analyzed by HFSS simulation. For input matching, balance of output signals and phase linearity at each output port, one circular hole has been etched out on the circuit surface. 1:2 and 1:3 power dividers/combiners designed by this study have been compared with the same circuits designed by the method of [10] in terms of S-parameters. As a result, it has been found that the modified structure of power divider/combiner have improved return loss more than 20 dB and another 18 dB, respectively, at 2 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.1
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• pp.36-45
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• 2010

In this paper, we propose a new design method to design a wireless power transfer system using loop antennas for consumer electronics. This method can simply design a wireless power transfer system only using measurements of coupling coefficients and simple equations of equivalent circuit model about loop antennas without complicated electromagnetic analysis. Using the proposed design method, a wireless power transfer system with a pair of loop antennas operating at the frequency of 13.56 MHz, which have a dimension of $50{\times}50\;cm^2$, is designed and implemented. The input return loss, coupling coefficient, efficiency, and input impedance variation with respect to a distance between loop antennas were measured. The proposed design method provides good agreements between measured and predicted results. Also, the wireless power transfer system with impedance matching circuits designed by the proposed design method shows two times higher efficiency characteristics than the case with the general $50\;{\Omega}$ impedance matching circuits. Therefore, we verified that our design method could be an effective tool to design a wireless power transfer 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.53-59
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• 2008

In this paper, a novel dual-band high-efficiency class-F power amplifier using the composite right/left-handed (CRLH) transmission lines (TLs) has been realized with one RF Si lateral diffusion metal-oxide-semiconductor field effect transistor (LDMOSFET). The CRLH TL can lead to metamaterial transmission line with the dual-band tuning capability. The dual-band operation of the CRLH TL is achieved by the frequency offset and the nonlinear phase slope of the CRLH TL for the matching network of the power amplifier. Because the control of the all harmonic components is very difficult in dual-band, we have managed only the second- and third-harmonics to obtain the high efficiency with the CRLH TL in dual-band. Also, the proposed power amplifier has been realized by using the harmonic control circuit for not only the output matching network, but also the input matching network for better efficiency. Two operating frequencies are chosen at 880 MHz and 1920 MHz in this work. The measured results show that the output power of 39.83 dBm and 35.17 dBm was obtained at 880 MHz and 1920 MHz, respectively. At this point, we have obtained the power-added efficiency (PAE) of 79.536 % and 44.04 % at two operation frequencies, respectively.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.749-754
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• 2021

In order to maximize the matching ratio between the scintillation pixel and the photosensor of the PET detector using a small number of photosensor, various arrays of scintillation pixels and four photosensors were used. The array of scintillation pixels consisted of six cases from 6 × 6 to 11 × 11. The distance between the photosensors was applied equally to all scintillation pixels, and the arrangement was expanded by reducing the size of scintillation pixel. DETECT2000 capable of light simulation was used to acquire flood images of the designed PET detectors. At the center of each scintillation pixel array, light generated through the interaction between extinction radiation and scintillation pixels was generated, and the light was detected through for four photosensors, and then a flood image was reconstructed. Through the reconstructed flood image, we found the largest arrangement in which all the scintillation pixels can be distinguished. As a result, it was possible to distinguish all the scintillation pixels in the flood image of 8 × 8 scintillation pixel array, and from the 9 × 9 scintillation pixel flood image, the two edge scintillation pixels overlapped and appeared in the image. At this time, the matching ratio between the scintillation pixel and the photosensor was 16:1. When a PET system is constructed using this detector, the number of photosensors used is reduced and the cost of the oveall system is expected to be reduced through the simplification of the signal processing circuit.