• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.6 s.336
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• pp.67-74
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• 2005

In this paper, high LO-RF isolation W-band MIMIC single-balanced mixer was designed and fabricated using a branch line coupler and a $\lambda$/4 transmission line. The simulation results of the designed 94 GHz balun show return loss of -27.9 dB, coupling of -4.26 dB, and thru of -3.77 dB at 94 GHz, respectively. The isolation and phase difference were 23.5 dB and $180.2^{\circ}$ at 94 GHz. The W-band MIMIC single-balanced mixer was designed using the 0.1 $\mu$m InGaAs/InAlAs/GaAs Metamorphic HEMT diode. The fabricated MHEMT was obtained the cut-off frequency(fT) of 189 GHz and the maximum oscillation frequency(fmax) of 334 GHz. The designed MIMIC single-balanced mixer was fabricated using 0.1 $\mu$m MHEMT MIMIC Process. From the measurement, the conversion loss of the single-balanced mixer was 23.1 dB at an LO power of 10 dBm. Pl dB(1 dB compression point) of input and output were 10 dBm and -13.9 dBm respectively. The LO-RF isolations of single-balanced mixer was obtained 45.5 dB at 94.19 GHz. We obtained in this study a higher LO-RF isolation compared to some other balanced mixers in millimeter-wave frequencies.

• International journal of advanced smart convergence
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• v.9 no.1
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• pp.172-176
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• 2020

The implementation of a low phase noise voltage controlled oscillator (VCO) is important for the signal integrity of wireless communication terminal. A low phase noise wideband VCO for a wireless local area network (WLAN) application is presented in this paper. A 6-bit coarse tune capacitor bank (capbank) and a fine tune varactor are used in the VCO to cover the target band. The simulated oscillation frequency tuning range is from 8.6 to 11.6 GHz. The proposed VCO is desgned using 65 nm CMOS technology with a high quality (Q) factor bondwire inductor. The VCO is biased with 1.8 V VDD and shows 9.7 mA current consumption. The VCO exhibits a phase noise of -122.77 and -111.14 dBc/Hz at 1 MHz offset from 8.6 and 11.6 GHz carrier frequency, respectively. The calculated figure of merit(FOM) is -189 dBC/Hz at 1 MHz offset from 8.6 GHz carrier. The simulated results show that the proposed VCO performance satisfies the required specification of WLAN standard.

• ETRI Journal
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• v.27 no.6
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• pp.685-690
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• 2005

DC and RF characteristics of $0.15{\mu}m$ GaAs power metamorphic high electron mobility transistors (MHEMT) have been investigated. The $0.15{\mu}m{\times}100{\mu}m$ MHEMT device shows a drain saturation current of 480 mA/mm, an extrinsic transconductance of 830 mS/mm, and a threshold voltage of -0.65 V. Uniformities of the threshold voltage and the maximum extrinsic transconductance across a 4-inch wafer were 8.3% and 5.1%, respectively. The obtained cut-off frequency and maximum frequency of oscillation are 141 GHz and 243 GHz, respectively. The $8{\times}50{\mu}m$ MHEMT device shows 33.2% power-added efficiency, an 18.1 dB power gain, and a 28.2 mW output power. A very low minimum noise figure of 0.79 dB and an associated gain of 10.56 dB at 26 GHz are obtained for the power MHEMT with an indium content of 53% in the InGaAs channel. This excellent noise characteristic is attributed to the drastic reduction of gate resistance by the T-shaped gate with a wide head and improved device performance. This power MHEMT technology can be used toward 77 GHz band applications.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1345-1346
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• 2006

본 논문에서는 솔레노이드 형태의 칩 인덕터와 나선형태의 박막 인덕터에 대하여 주파수 특성을 비교 분석하여 장 단점을 정의하고자 한다. 솔레노이드형 RF 칩 인덕터는 $1.0mm{\times}0.5mm{\times}0.5mm$의 크기에 11nH의 인덕턴스를 가질 수 있도록 6회 권선하였다. 나선형 박막 인덕터는 $213{\mu}m{\times}250{\mu}m{\times}304{\mu}m$의 크기에 11nH의 인덕턴스를 가질 수 있도록 7회 권선하였다. 시뮬레이션을 위하여 AnSoft사의 HFSS를 이용하였으며, 이 결과 솔레노이드형 RF 칩 인덕터는 2GHz에서 77 정도의 품질계수와 5.6GHz의 SRF를 가진다. 반면 나선형 박막 인덕터는 2GHz에서 14 정도의 품질계수와 4.5GHz의 SRF를 가진다. 성능면에서는 솔레노이드형 RF 칩 인덕터가 우수한 특성을 나타내었으나 크기를 감소시키는데 제한을 받으므로, 향후 소형 경량화를 위하여 박막 인덕터의 개발은 필수적이며, 성능을 더욱 향상시키기 위하여 나선형태와 재료의 개발이 필수적이라 하겠다.

• Journal of IKEEE
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• v.27 no.1
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• pp.71-77
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• 2023

In this paper, a dual-band stopband frequency selective surface that can be applied to Wi-Fi 6E systems is designed to block external interfering signals with adjacent operating frequency spectrum in indoor wireless LAN environments. The proposed frequency selective surface structure has frequency blocking characteristics in the 2.4GHz and 6GHz bands, and is realized through a modified crossed dipole structure and an interlocking puzzle form between unit structures. The proposed structure is designed to have stable frequency response characteristics with respect to incident angle and polarization, and the experimental results show good agreement with the simulation results for incident waves from 0° to 45°.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.3
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• pp.253-260
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• 2016

This paper proposes a planar Log-Periodic Dipole Array(LPDA) antenna with light-weight supporting structure for installing on an aircraft. The proposed antenna is designed by applying a planar skeleton supporting structure that has light-weight for an aircraft and is capable of withstanding structural vibration. The material of the planar skeleton supporting structure is a Polyether ether ketone(Peek) which has excellent characteristics on strength and temperature. The proposed antenna is fabricated by attaching the radiating elements of the LPDA on both sides of the supporting structure. The changed input impedance due to the dielectric material of the supporting structure was compensated for by controlling the distance and length of several radiating elements. The 10-dB return loss bandwidths of the designed planar LPDA antenna with light-weight supporting structure are obtained as 0.4~3.1 GHz(7.3:1) in the simulation and 0.41~3.5 GHz(8.2:1) in the measurement. The average gains in 0.5~3 GHz band are 6.77 dBi in the simulation and 6.55 dBi in the measurement. Therefore, we confirm that the designed antenna is appropriate to be installed on an aircraft due to its light-weight structure and wideband directional radiation characteristics.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.4
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• pp.484-494
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• 2014

We describe a digitally controlled oscillator (DCO) which compensates the frequency variations for process, voltage, and temperature (PVT) variations with an accuracy of ${\pm}2.6%$ at 2.5 GHz. The DCO includes an 8 phase current-controlled ring oscillator, a digitally controlled current source (DCCS), a process and temperature (PT)-counteracting voltage regulator, and a bias current generator. The DCO operates at a center frequency of 2.5 GHz with a wide tuning range of 2.2 GHz to 3.0 GHz. At 2.8 GHz, the DCO achieves a phase noise of -112 dBc/Hz at 10 MHz offset. When it is implemented in an all-digital phase-locked loop (ADPLL), the ADPLL exhibits an RMS jitter of 8.9 ps and a peak to peak jitter of 77.5 ps. The proposed DCO and ADPLL are fabricated in 65 nm CMOS technology with supply voltages of 2.5 V and 1.0 V, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.117-120
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• 2008

In this paper, we developed the EM wave absorber for eliminating false images in collision-avoidance radar. First of all, we fabricated some samples in different composition ratio of $TiO_2$ and CPE. And the relative permittivities of samples are calculated from S-parameter of samples by using 1-port method. We designed and fabricated the EM wave absorber by using the calculated relative permittivity. As a result, the EM wave absorber with composition of $TiO_2$:CPE=70:30 wt% has thickness of 1.85 mm and absorption ability higher than 20 dB in the frequency range 76-77 GHz.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.35-41
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• 2008

The most important requirement for the automotive radars is the simultaneous target range and velocity measurement under environment of multi-target, clutters, multi-path, and so on. If the many vehicles with 77GHz FMCW(Frequency Modulation Continuous Wave) radar system are in the near area we should consider the interference signals occurred by other radar systems because these signals reduce exact detection of range and velocity. In this paper, we propose the interference cancellation method, which each vehicle radar transmits chirp trains with the different frequency sweep shapes. The proposed method is applied into the various applications such as an intelligent vehicle, Robot, and UGV(Unmanned Ground Vehicle).

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.1
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• pp.24-30
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• 2010

In this paper, a novel electrically small monopole type resonant antenna is proposed. The very short length monopole (${\iota}{\approx}{\lambda}_g/15$ ) acts as a capacitive element and the slot on the ground structure acts as an inductive element, hence the combined system with these two elements thus form an LC resonator. The equivalent circuit model of the antenna structure was used to analysis and qualify the design correctness. Although the proposed antenna has very small size, it shows good performances. The measured maximum gain and radiation efficiency of the fabricated antenna at the frequency of 2.1 GHz was 3.6 dBi and 77.8 %, respectively.