• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.10
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• pp.971-978
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• 2013

This work presents a W band frequency synthesizer which is composed of 26 GHz VCO, Phase Locked Loop and frequency tripler using 65 nm RF CMOS process. Frequency tuning range of 26 GHz VCO covers the band from 22.8~26.8 GHz and final output frequency of the tripler is from 74 to 75.6 GHz. The fabricated frequency synthesizer consumes 75.6 mW and its phase noise is -75 dBc/Hz at 1 MHz offset, -101 dBc/Hz 10 MHz offset respectively.

• Journal of IKEEE
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• v.26 no.1
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• pp.77-82
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• 2022

The effect of the bias network on the performance of the W-band power amplifier(PA) was investigated. The performances of the typical RC and radial stub networks were examined, and a hybrid network was proposed for W-band application and its performance was confirmed. To verify this, a W-band PA was designed using a 60-nm GaN pHEMT process. When hybrid networks were applied, the PA had improved stability in all frequency bands, secured about 9 dB of power gain at operating frequencies 87 GHz to 93 GHz, and the maximum PAE was found to be about 12.3% at output power of 26.7 dBm.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.235-240
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• 2005

This paper presents a dual band circularly polarized microstrip patch antenna. The antenna consists of two corner truncated patches implemented in one plane and single feed point. The input signal is directly excited to the patch 2 and the patch 1 is fed from patch 2 by coupling between two patches. The antenna is operated at 900 MHz and 2.45 GHz bands and has the right hand circularly polarized radiation pattern at all. The measured gains of the antenna are 2.95 dBic at 900 MHz band and 4.6 dBic at 2.45 GHz band.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.72-80
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• 1996

This paper presetns the development of a SSPA operating at KU-band(14~14.5 GHz) in order of replace TWTA used in the terrestria transponder of a satellite communication. The driving stage of SSPA uses internally matched 2W, 4W, 8W FET and the power stage is coupled with two internally matched 8W FET by branch-line cominer. The SSPA is fabricated with oth the RF circuit and the bias circuitry operating temperature compensation, regulation and sequence on aluminum housing. The SSPA testing resutls implemented in this way show 24.8$\pm$1dB small-signal gain, 41dBm P1dB power, a typical two tone C/IM3, -33dBc with single carrier backed off 6dB from p1dB, and gain stability over temeprature (-30~50)$\pm$1dB.

• YAKHAK HOEJI
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• v.30 no.6
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• pp.343-347
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• 1986

Korean ginseng was purified to obtain radioprotective protein fractions by buffer extraction, ammonium sulfate fractionation, CM-cellulose column chromatography, heat inactivation and Sephadex G-75 column chromatography. The final three fractions, GI, GII and GIII were subjected to Disc-polyacrylamide gel electrophoresis (PAGE) and SDS-PAGE. The molecular weights(M.W.) of native and denatured proteins were estimated by using regression line equations obtained from the mobilities of standard proteins. As the results, in Disc-PAGE, the GI fraction showed two protein bands with M.W. of above 213, 000 and 55, 000, GII showed one band with M.W. of 44, 000 and GIII, also one band with M.W. of 19, 000. In SDS-PAGE, GI fraction gave four subunit bands with M.W. of above 114, 000, 27, 000, 24, 000 and 19, 000, GII gave two bands with M.W. of 46, 000 and 22, 000, and GIII, one band of 19, 000.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.4
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• pp.314-319
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• 2019

In this study, we propose a W-band frequency modulated continuous wave(FMCW) radar altimeter that can measure the altitude based on the frequency differences of transmitted and received signals. This W-band FMCW system is powered by an altitude control algorithm, which we propose to help prevent collisions of drones with obstacles in real deployment by measuring the relative altitude. It is shown that this algorithm enables the drone to be positioned within a 3 % error of altitude from the desired input height. The chip used in the W-band transmitter and receiver was fabricated using a 65-nm CMOS process, and a horn antenna was directly fed by incorporating an embedded waveguide feeder into the chip. The clutter spectra observed in terrains including soil, grass, and calm lake water were measured and compared, confirming the reflectivity characteristics of various surfaces of different water contents.

• Journal of IKEEE
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• v.28 no.3
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• pp.445-450
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• 2024

This paper presents a varactor-less voltage-controlled oscillator (VCO) at W-band (75-110 GHz) with a compact size in a 0.15-㎛ GaAs pHEMT technology. For varactor-less frequency tuning, an inductive tuning circuit is employed. An active inductor is realized by the common-gate stage with gate termination and shows a wide tuning range with a high quality factor (Q-factor) compared with the conventional varactor diode. Colpitts topology with source feedback is employed for the oscillation core of the VCO. The varactor-less VCO exhibits a measured tuning range of 5.8 % and peak output power of 5.7 dBm at 88 GHz while the 146 mW of dc power is dissipated. Due to compact layout design, the chip size is only 0.48 mm².

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.95-98
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• 2007

In this paper, we make an analysis of electromagnetic wave absorption properties of $TiO_2$ in W-band. Therefore, we fabricated some samples in different composition ratio of $TiO_2$ and CPE. And the material properties of samples are calculated from S-parameter of samples using $\ell-2\ell$ method. We analyze absorption properties and complex relative permittivitis of samples. As a result, it has verified that absorption properties of sample containing $TiO_2:CPE=70:30wt.%$ have been excelled in W-band.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.50-54
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• 2015

In this paper, we report on a high performance 94 GHz MMIC mixer module using 0.1-um metamorphic high electron mobility transistors (MHEMTs). A modified resistive mixer with a RF amplifier was proposed in this work for low conversion loss and high LO-RF isolation. The MMIC mixer module was fabricated using a MMIC chip and CPW-waveguide transitions. The fabricated mixer chip and module showed a low conversion loss of 6.3 dB and 9.5 dB, and LO-RF isolations of 24.8 and 30.4 dB at 94 GHz, respectively. This results are superior to those of previously W-band (75-110 GHz) MMIC mixers.

• Journal of IKEEE
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• v.23 no.2
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• pp.425-430
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• 2019

This work describes the design and characterization of a X-band power amplifier (PA) monolithic microwave integrated circuit (MMIC) using a $0.25{\mu}m$ gate length gallium nitride (GaN) high electron mobility transistor (HEMT) technology. The developed X-band power amplifier MMIC has small signal gain of over 22.7 dB and saturated output power of 43.02 dBm (20.04 W) over the entire band of 9 to 10 GHz. Maximum saturated output power is a 43.84 dBm (24.21 W) at 9.5 GHz. Its power added efficiency (PAE) is 41.0~51.24% and the chip dimensions are $3.7mm{\times}2.3mm$, generating the output power density of $2.84W/mm^2$. The developed GaN power amplifier MMIC is expected to be applied in a variety of X-band radar applications.