• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.167-170
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• 2002

The design and fabrication of Q-band 3-stage monolithic microwave integrated circuit(MMIC) driver and power amplifiers for WLAN are presented using 0.2${\mu}{\textrm}{m}$ AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor(PHEMT). In each stage of the MMIC DA, a negative feedback is used for both broadband and good stability. The MMIC PA has employed a balanced configuration to overcome these difficulties and achieve high power with low VSWR over a wide frequency range. In the MMIC DA, the measurement results arc achieved as an input return loss under -4dB, an output return loss under -l0dB, a gain of 14dB, and a PldB of 17dB at C-band(36~ 44GHz). The chip size is 28mm$\times$1.3mm. The developed MMIC PA has the l0dB linear gain over 360Hz to 420Hz band and 22dBm PldB performance at 400Hz. The size of fabricated MMIC PA is 4mm x3mm. These results closely match with design results. This MMIC DA Sl PA will be used as the unit cells to develop millimeter-wave transmitters for use in wideband wireless LAN systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.7
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• pp.944-950
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• 1993

Diodes and GaAs have been commonly used in a mixer design until recently. However, diodes are not preferred to use at the front-end of DBS receiver due to the conversion loss large noise. HEMT has larger conversion gain and better noise characteristics comparing with GaAs MESFET. This paper describes the design procedure, structure, and performance of a mixer, utilizaing HEMT designed by OKI Co. . A mixer configuration in which the local oscillator(LO) signal is applied to the gate is used. When the LO power is 0.01 dBm, the conversion gain of 3.7dB is obtained at IF and the 3 dB bandwidth is 400MMz.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.11
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• pp.1367-1372
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• 1988

In this paper, we have optimized the computation of the CSP - LOC (Channel Substrate Planar-Large Optical Cavity) structure to design the gith power (Ga, Al) As/GaAs CSP-LOC laser diode. The parameters of the device on the bases of experimental datas include the effects of the various layer thickness, material absorption coefficients, stripe width and so forth. At active layer ($d_2$)=0.08 um with optical layer ($d_3$)=0.5 um and $d_2$ = 0.1 um with $d_3$ = 0.4 um, we find the narrower beam divergence and stable high power in the lowest-order mode without the phenomenon of spatial hole burning. The results of theoretical computation show good agreement with experimental measurements made on LPE grown CSP-LOC. Finally, we developed an practical program and the program is applicable to the CSP-LOC lasers with any materials.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.29-34
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• 2021

For the purpose of Application to the small radar sensor, the MMIC Chips, which are the core component of the W-band, was designed in Korea according to the characteristics of the transceiver and manufactured by 60nm GaN and 0.1㎛ GaAs pHEMT process. The output power of PA is 28 dBm at center frequency of W-band and Noise figure is 6.7 dB of switch and LNA MMIC. Output power and Noise figure of MMIC chips developed in domestic was applied to the transmitter and receiver module through W-band waveguide low loss transition structure design and impedance matching to verify the performance after the fabrication are 26.1~27.7 dBm and 7.85~10.57 dB including thermal testing, and which are close to the analysis result. As a result, these are judged that the PA and Switch and LNA MMICs can be applied to the small radar sensor.

• Korean Journal of Materials Research
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• v.22 no.4
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• pp.185-189
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• 2012

We report plasma-assisted molecular beam epitaxy of $In_XGa_{1-X}N$ films on c-plane sapphire substrates. Prior to the growth of $In_XGa_{1-X}N$ films, GaN film was grown on the nitride c-plane sapphire substrate by two-dimensional (2D) growth mode. For the growth of GaN, Ga flux of $3.7{\times}10^{-8}$ torr as a beam equivalent pressure (BEP) and a plasma power of 150 W with a nitrogen flow rate of 0.76 sccm were fixed. The growth of 2D GaN growth was confirmed by $in-situ$ reflection high-energy electron diffraction (RHEED) by observing a streaky RHEED pattern with a strong specular spot. InN films showed lower growth rates even with the same growth conditions (same growth temperature, same plasma condition, and same BEP value of III element) than those of GaN films. It was observed that the growth rate of GaN is 1.7 times higher than that of InN, which is probably caused by the higher vapor pressure of In. For the growth of $In_xGa_{1-x}N$ films with different In compositions, total III-element flux (Ga plus In BEPs) was set to $3.7{\times}10^{-8}$ torr, which was the BEP value for the 2D growth of GaN. The In compositions of the $In_xGa_{1-x}N$ films were determined to be 28, 41, 45, and 53% based on the peak position of (0002) reflection in x-ray ${\theta}-2{\theta}$ measurements. The growth of $In_xGa_{1-x}N$ films did not show a streaky RHEED pattern but showed spotty patterns with weak streaky lines. This means that the net sticking coefficients of In and Ga, considered based on the growth rates of GaN and InN, are not the only factor governing the growth mode; another factor such as migration velocity should be considered. The sample with an In composition of 41% showed the lowest full width at half maximum value of 0.20 degree from the x-ray (0002) omega rocking curve measurements and the lowest root mean square roughness value of 0.71 nm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.8
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• pp.105-111
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• 2004

In this paper, millimeter-wave high gain and broadband MHEMT cascode amplifiers were designed and fabricated. The 0.1 ${\mu}{\textrm}{m}$ InGaAs/InAlAs/GaAs Metamorphic HEMT was fabricated for cascode amplifiers. The DC characteristics of MHEMT are 640 mA/mm of drain current density, 653 mS/mm of maximum transconductance. The current gain cut-off frequency(f$_{T}$) is 173 GHz and the maximum oscillation frequency(f$_{max}$) is 271 GHz. By using the CPW transmission line, the cascode amplifier was designed the matched circuit for getting the broadband characteristics. The designed amplifier was fabricated by the MHEMT MIMIC process that was developed through this research. As the results of measurement, the 1 stage amplifier obtained 3 dB bandwidth of 37 GHz between 31.3 to 68.3 GHz. Also, this amplifier represents the S21 gain with the average 9.7 dB gain in bandwidth and the maximum gain of 11.3 dB at 40 GHz. The 2 stage amplifier has the broadband characteristics with 3 dB bandwidth of 29.5 GHz in the frequency range from 32.5 to 62.0 GHz. The 2 stage cascode amplifier represents the high gain characteristics with the average gain of 20.4 dB in bandwidth and the maximum gain of 22.3 dB at 36.5 GHz.z.z.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.60-60
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• 2018

This study was carried out to develop the seed propagation method of Dicenta spectabilis (L.) Lem. which is an ornamental plant native to Korea. In the previous studies, it was found that the seeds of D. spectabilis were morphophysiologically dormant (MPD), and high and low temperature of stratification were continuously required for the embryo growth and germination of the seeds. Especially, it was most effective to store for 1 month at $20^{\circ}C$ and then to transfer to $4^{\circ}C$. The treatment of $GA_3$ was carried out to promote embryo development and germination. The seeds were submerged in 100, 200 or $500mg{\cdot}L^{-1}$ $GA_3$ for 72 hours and then stored at various conditions as follow. The temperature conditions disposed of this experiment were 1 month at 10, 15, 20, and $25^{\circ}C$ or 2, 4, 8, and 12 months at $4^{\circ}C$, respectively. As a result, the length of embryo and germination rate of the seeds were the best when stored at $4^{\circ}C$ for 8 months after $500mg{\cdot}L^{-1}$ $GA_3$ treatment. Besides, when the seeds stored at $4^{\circ}C$, significant differences in embryo length and germination rate were shown with $GA_3$ concentration and storage period. It was also proved that high-concentration of $GA_3$ could replace the high temperature and could promote germination. Consequentially, the D. spectabilis seeds were classified into intermediate simple levels among MPD types.

• Journal of electromagnetic engineering and science
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• v.4 no.1
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• pp.37-42
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• 2004

In this paper, LNB(low noise block) downconverter MMIC is designed for Ku-band satellite communication system using InGaP/GaAs HBT high linear process. Designed MMIC consists of low noise amplifier, double balanced mixer, and IF amplifier with a total chip area of 2.6${\times}$1.1 $\textrm{mm}^2$. Designed MMIC has the characteristics of over 37.5 ㏈ conversion gain, 14 ㏈ noise figure, ripple of 3 ㏈, and output-referred $P_{1dB}$TEX>(1 ㏈ compression power) of 2.5 ㏈m with total power dissipation of 3 V, 50 mA.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.5
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• pp.40-47
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• 1998

This paper report sthe design, fabrication and characterization of an AlGaAs/GaAs HBT (heterojunction bipolar transistor) with an air-bridge isolation structure which is made to improve high frequency characteristics for the application to the mobile communication system in the next genration. We found that the size, shape and structure of HBT have an effect on the high frequency operation. The measured dc and ac characteristics of the four type HBTs were compared and analyzed. An E-type HBT with an air-bridge structure by undercut etching exhibited .beta.=56, $V_{off-set}$ = 0.3 V, B $V_{CEO}$=7.0V with $f_{T}$=40 GHz and $f_{max}$=45GHz at a collector current density of 7.1*10$^{4}$ A/c $m^{2}$.>.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.85-90
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• 2002

$RuO_2$/GaN and related contacts were investigated for Schottky contacts in GaN-Based optical and electronic devices. We demonstrated that an $RuO_2$ film forms a stable Schottky contact on a GaN layer with a barrier height (${\Phi}_B$) of 1.46 eV and transmittance of 70% in the visible and near UV region. $RuO_2$/GaN Schottky diode showed a breakdown at over -50V and leakage current of only 0.3 nA at -5V. The $RuO_2$/GaN Schottky type photodetector had the UV/Visible rejection ratio of over $10^5$ and the responsivity of 0.23 A/W at 330 nm. The $RuO_2$ gate AlGaN/GaN EFET exhibited high drain current ($I_d$) of 689.3 mA/mm and high transconductance ($g_m$) of 197.4 mS/mm. Cut-Off frequency ($f_t$) and maximum operating frequency ($f_{max}$) were measured as 27.0 GHz and 45.5 GHz, respectively.