• Journal of electromagnetic engineering and science
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• v.5 no.3
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• pp.112-116
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• 2005

This paper presents a broadband two-stage low noise amplifier(LNA) operating from 3 to 10 GHz, designed with 0.18 ${\mu}m$ RF CMOS technology, The cascode feedback topology and broadband matching technique are used to achieve broadband performance and input/output matching characteristics. The proposed UWB LNA results in the low noise figure(NF) of 3.4 dB, input/output return loss($S_{11}/S_{22}$) of lower than -10 dB, and power gain of 14.5 dB with gain flatness of $\pm$1 -dB within the required bandwidth. The input-referred third-order intercept point($IIP_3$) and the input-referred 1-dB compression point($P_{ldB}$) are -7 dBm and -17 dBm, respectively.

• Journal of electromagnetic engineering and science
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• v.10 no.1
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• pp.35-38
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• 2010

A fully integrated parallel-coupled 6-GHz quadrature voltage-controlled oscillator (QVCO) has been designed. The symmetrical parallel-coupled quadrature VCO is implemented using 0.13-${\mu}m$ CMOS process. The measured phase noise is -101.05 dBc/Hz at an offset frequency of 1 MHz. The tuning range of 710 MHz is achieved with a control voltage ranging from 0.3 to 1.4 V. The average output phase error is about $1.26^{\circ}$ including cables and connectors. The QVCO dissipates 10 mA including buffer from the 1.5 V supply voltage. The output characteristic of the differential injection-locked frequency divider (DILFD), which has similar topology to the QVCO, is presented.

• Journal of electromagnetic engineering and science
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• v.9 no.3
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• pp.159-163
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• 2009

This paper presents the design and implementation of Q-band MMIC phase shifters using InGaAs PIN diodes. The topology using a thin-film microstrip line(TFMS) has been proposed to achieve the desired phase-shift as well as good loss characteristics. Five single-bit MMIC phase shifters have been implemented by using a developed BCB(benzocyclobutene)-based multi-layer fabrication technology. The developed phase shifters have less than 3.4 dB of insertion loss and better than 11 dB of input and output return loss in the frequency range of 43 to 47 GHz. To the authors' knowledge, this is the first demonstration of high-performance InGaAs PIN diode-based MMIC phase shifters operating at Q-band frequencies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.625-629
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• 2003

Low loss and high power MMIC limiters with GaAs PM diode were designed and fabricated. The new epitaxial structure of GaAs PIN diode was proposed in order to increase the high power capability. 2 types of limiter circuits have been designed and the limiting powers have been measured. Results indicated that the limiting power was depended on the circuit topology. Limiting power levels of 2-stage limiters are measured 16 ㏈m and 22 ㏈m at 14 ㎓, respectively.

• Journal of electromagnetic engineering and science
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• v.7 no.3
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• pp.134-137
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• 2007

This paper presents the design of the compact UHF Bandpass filter of CT-type with a novel mixed coupling topology. In further detail, this new coupling structure mathematically equals the transmission zero that enables particularly the better rejection performance in the stopband without increasing the filter's order. To envision this design concept, we fabricated a microstrip filter whose measurement proves to agree with the predicted performance and the suggested coupling structure reduces the overall size, and will be possibly used in the miniaturized UHF apparatus such as the RFID system.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.20-24
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• 2000

VoIP는 Packet Netwark(ATM, xDSL, Frame Relay, Cable Network)망을 이용하여 음성데이터를 전송 하는 기술로서 PSTN을 통해 음성데이터를 전송하는 것보다 비용절감의 효과가 크다. 본 연구에서는 최적의 VoIP 서비스 제공을 위한 음성/데이터 통합 네트워크 망을 설계하기 위하여 IP와 ATM을 이용한 서로 다른 2개의 망을 설계하여 지연과 Routing 정책, Traffic 추가 후 지연현상에 대하여 살펴보았다. 지연은 순수한 VoIP 망을 구성 할 경우 8-10ms. VoIP+ATM으로 망을 구성 할 경우 2ms로 나타났고, 라우팅 정책(RIP, IGRP, OSPF 적용)에서는 IP 또는 IP+ATM으로 망을 구성 할 경우 RIP는 25ms, IGRP는 22ms로 나타났고, OSPF를 이용할 경우 14ms로 평가되어 OSPF를 이용한 라우팅 정책을 설정하는 것이 바람직하다고 볼 수 있다. 결론적으로 본 연구의 결과 VoIP망을 구성 할 경우 IP+ATM을 기반으로 구축하면 보다 더 효과적인 인터넷 망을 구성할 수 있음을 확인하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.65-70
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• 2001

This paper presents a Receiver MMIC for the CDMA terminal. The complete circuit is composed of Low Noise Amplifier, Down Conversion Mixer, Intermediate Frequency Amplifier and Bias circuit. The Bias circuit implementation, which allows for compensation for threshold voltage and power supply voltage variation are provided. The proposed topology has high linearity and low noise characteristics. Results of the designed circuit are as follows: Overall conversion gain is 28.5 dB, input IP3 of LNA is 8 dBm, input IP3 of down conversion mixer is 0 dBm and total DC current consumption is 22.1 mA.

• Journal of electromagnetic engineering and science
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• v.18 no.2
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• pp.141-143
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• 2018

Two 110-GHz oscillators have been developed in 65-nm CMOS technology. To study the effect of layout on the circuit performance, both oscillators had the same LC cross-coupled topology but different layout schemes of the circuit. The oscillator with the conventional cross-coupled design (OSC1), showed an output power of -3.9 dBm at 111 GHz with a phase noise of -75 dBc/Hz at 1-MHz offset. On the other hand, OSC2, with a modified cross-coupled line layout, generated an output power of -2.0 dBm at 117 GHz with a phase noise of -77 dBc/Hz at 1-MHz offset. The result indicates that the optimized layout can improve key oscillator performances such as oscillation frequency and output power.

• Journal of Power Electronics
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• v.19 no.3
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• pp.744-750
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• 2019

A new type of auto-rotary PM mechanical flux-varying PM machine (ARPMMFVPMM) is proposed in this paper, which can overcome the problem where the air-gap magnetic field of a PM machine is difficult to freely adjust. The topology structures of the machine and the mechanical flux-adjusting device are given. In addition, the operation principle of flux-adjusting is analyzed in detail. Furthermore, the deformation of a spring with the speed variation is obtained by virtual prototype technology. Electromagnetic characteristics including the flux distribution, air gap flux density, flux linkage, electromagnetic-magnetic-force (EMF), and flux weakening ability are computed by 2D finite element method (FEM). Results show that the machine has some advantages such as the good field control ability.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.12
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• pp.935-941
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• 2018

In this study, we propose a suitable magnetic resonant wireless power transfer(WPT) system topology for size-limited implant medical devices(IMDs). The proposed modified series-parallel topology(mSPT) can be implemented by adding an inductor in series to the parallel-connected Rx coil and a capacitor. The topology achieves high efficiency when the Rx coil has a small inductance. The validity and operating conditions of the system are verified theoretically through circuit analysis. Experiments were conducted with bio-blocks, which are made of pork fat and muscle. When the Rx coils were inserted into the blocks at a depth of 2.5~10 mm, mSPT showed 17.79 % improved efficiency on average compared with the conventional series-series topology(SST). In the case of 32 dBm WPT in air, the Rx coil's heating rate for the mSPT was $0.18^{\circ}C/s$, whereas the SST was $0.75^{\circ}C/s$. It was confirmed that the mSPT is more suitable for an IMD-targeted WPT system.