• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6A
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• pp.697-704
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• 2004

This paper describes the design and fabrication of an MMIC variable gain LNA for 5GHz wireless LAN applications, using 0.5${\mu}{\textrm}{m}$ gate length GaAs MESFET transistors. The advantages of high gain and low noise performance of E-MESFETS and excellent linear performance of D-MESFETS are combined as a cascode topology in this design. Behavioral model equations are derived from the MESFET nonlinear current voltage characteristics by using Turlington's asymptote method in a cascode configuration. Using the behavioral model equations, a 4${\times}$50${\mu}{\textrm}{m}$ E-MESFET as a common source amplifier and a 2${\times}$50${\mu}{\textrm}{m}$ D-MESFET as a common gate amplifier are determined for the cascode amplifier. The fabricated variable gain LNA shows a noise figure of 2.4dB, variable gain range of more than 17dB, IIP3 of -4.8dBm at 4.9GHz, and power consumption of 12.8mW.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.5
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• pp.100-105
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• 2010

A multi-band low noise amplifier (LNA) is designed in 90 nm RF CMOS process for 3GPP LTE (3rd Generation Partner Project Long Term Evolution) applications. The designed multi-band LNA covers the eight frequency bands between 1.85 and 2.8 GHz. A tunable input matching circuit is realized by adopting a switched capacitor array at the LNA input stage for providing optimum performances across the wide operating band. Current steering technique is adopted for the gain control in three steps. The performances of the LNA are verified through post-layout simulations (PLS). The LNA consumes 17 mA at 1.2 V supply voltage. It shows a power gain of 26 at the normal gain mode, and provides much lower gains of 0 and -6.7 in the bypass-I and -II modes, respectively. It achieves a noise figure of 1.78 dB and a IIP3 of -12.8 dBm over the entire band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.169-174
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• 2018

In this paper, a design method for a wideband LPF for harmonic suppression applications is investigated. The proposed wideband LPF is comprised of four circular slot pairs with different diameters, which are added symmetrically in the ground plane of a CPW transmission line. Four circular slot pairs act as a defected ground structure and provide a wideband low pass characteristic. The circular slot with the smallest diameter is located at the side of port 1, and the diameter of the circular slot is increased as it goes toward port 2. The low pass characteristics of each circular slot are compared with the proposed wideband LPF. The final designed LPF was fabricated on FR4 substrate, and its characteristics were tested. The measured S11 characteristic was maintained at over -3.3 dB in the frequency range of 1.89-20.00 GHz band, whereas the S21 characteristic was less than -21.4 dB in the frequency range of 2.66-20.00 GHz.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.925-928
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• 2005

In this study, we fabricated the DAMLs using surface micromachining technology as well a low loss coupler for the millimeter-wave band applications using these DAMLs. The structure of DAML is that a signal line is supported on ground plane by dielectric posts. Therefore it has advantages about the loss characteristic and the stable structure. The other advantage of the DAML process is a simple and convenient technique using 4 mask steps, even if it has a micromachining technology. The lowest loss of the fabricated DAML was obtained 2.2 dB/cm at 110 GHz. To obtain the low loss characteristic, couplers were designed and fabricated by using DAMLs. The fabricated ring hybrid coupler has the coupling of 3.58 dB and the thru of 3.31 dB at 60 GHz. We can also obtain the coupling of 3.42 dB, the thru of 3.82 dB from fabricated branch line coupler at 60 GHz.

• Journal of Sensor Science and Technology
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• v.27 no.1
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• pp.40-46
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• 2018

In this paper, we focus on optimization of a boron ($^{11}B$)-implanted n type Si epi substrate for obtaining near-zero temperature coefficient of resistance (TCR) at temperature range from 25 to $125^{\circ}C$. The $^{11}B$-implantation on the N type-Si epi substrate formed isolation from the rest of the N-type Si by the depletion region of a PN junction. The TCR increased as the temperature of rapid thermal anneal (RTA) was increased at the temperature range from $900^{\circ}C$ to $1000^{\circ}C$ for the $p^+$ contact with implantation at dose of $1E16/cm^2$, but sheet resistance of this film was decreased. After the optimization of anneal process condition, the TCR of $1126.7{\pm}30.3$ (ppm/K) was obtained for the $p^-$ resistor-COB package chips contained $p^+$ contact with the implantation of $5E14/cm^2$. This shows the potential of the $^{11}B$-implanted n type Si epi substrate as a resistor for pressure sensor in thermal stable environment applications..

• Journal of The Korean Astronomical Society
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• v.25 no.1
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• pp.11-21
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• 1992

Applying mass model to disk galaxy NGC 300, since the observed rotation curve of NGC 300 is flatter than Toomre's mass model n = 1, two cases are used; obtaining parameters $a^n$ and $b^n$ from the polynomial fitting of the observed rotation curve (case A) and from the least square fitting between the observed rotation curve and model rotation curve (case B). In any case, n bas a fixed value of 1. Brandt's mass model is also discussed. which has a shape parameter n = 1.4. Calculated total mass and total mass to luminosity ratio are $3.3{\times}10^{10}M_{\odot}$, l2.1 for case A and $2.8{\times}10^{10}M_{\odot}$, 10.3 for case B. In case of Brandt's model, the values are $4.2{\times}10^{10}M_{\odot}$ and 15.4. The rise in the local mass to luminosity ratio in the outer part of NGC 300 implies existence of massive halo. Other dynamical properties are also discussed.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.1
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• pp.39-44
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• 2008

In this paper, fully embedded 2.4GHz WLAN band pass filter (BPF) was investigated into a multi-layered organic packaging substrate using high Q spiral stacked inductors and high Dk MIM capacitors for low cost RF System on Package (SOP) applications. The proposed 2.4GHz WLAN BPF was designed by modifying chebyshev second order filter circuit topology. It was comprised of two parallel LC resonators for obtaining two transmission zeros. It was designed by using 2D circuit and 3D EM simulators for finding out optimal geometries and verifying their applicability. It exhibited an insertion loss of max -1.7dB and return loss of min -l7dB. The two transmission zeros were observed at 1.85 and 6.7GHz, respectively. In the low frequency band of $1.8GHz{\sim}1.9GHz$, the stop band suppression of min -23dB was achieved. In the high frequency band of $4.1GHz{\sim}5.4GHz$, the stop band suppression of min -l8dB was obtained. It was the first embedded and the smallest one of the filters formed into the organic packaging substrate. It has a size of $2.2{\times}1.8{\times}0.77mm^3$.

• Journal of IKEEE
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• v.21 no.3
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• pp.320-330
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• 2017

Porous nanosilica (PNS) has been identified as a potential candidate for controlled drug delivery. However, unmodified PNS-based carriers exhibited an initial release of loaded bioactive agents, which may limit their potential clinical applications. In this study, the surface of PNS was functionalized with adamantylamine (ADA) via disulfide bonds (-S-S-), PNS-S-S-ADA, which was then modified with cyclodextrin (CD)-heparin (Hep) (CD-Hep), PNS-S-S-CDH, for redox triggered rhodamine B (RhB) delivery. The obtained samples were then characterized by proton nuclear magnetic resonance ($^{1}H\;NMR$), Fourier transform infrared (FTIR), and transmission electron microscope (TEM). These results showed that PNS-S-S-CDH was successfully formed with spherical shape and average diameter of $45.64{\pm}2.33nm$. In addition, RhB was relatively encapsulated in the PNS-S-S-CDH (RhB@PNS-S-S-CDH) and slowly released up to 3 days. The release of RhB, in particular, was triggered due to the cleavage of -S-S- in the presence of dithiothreitol (DTT). It might be anticipated that the modified PNS can be used as redox-responsive drug delivery system in cancer therapy.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.1917-1925
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• 2020

New versions of ENDF/B and JEFF data libraries have been released during the past two years with significant updates in the neutron reaction sublibrary and the thermal neutron scattering sublibrary. In order to get a more comprehensive impression of the criticality quality of these two latest neutron data libraries, and to provide reference for the selection of the evaluated nuclear data libraries for the science and engineering applications of the Reactor Monte Carlo code RMC, the criticality benchmarking of the two latest neutron data libraries has been performed. RMC was employed as the computational tools, whose processing capability for the continuous representation ENDF/B-VIII.0 thermal neutron scattering laws was developed. The RMC criticality validation suite consisting of 116 benchmarks was established for the benchmarking work. The latest ACE format data libraries of the neutron reaction and the thermal neutron scattering laws for ENDF/B-VIII.0, ENDF/B-VII.1, and JEFF-3.3 were downloaded from the corresponding official sites. The ENDF/B-VII.0 data library was also employed to provide code-to-code validation for RMC. All the calculations for the four different data libraries were performed by using a parallel version of RMC, and all the calculated standard deviations are lower than 30pcm. Comprehensive analyses including the C/E values with uncertainties, the δk/σ values, and the metrics of χ² and < |Δ| >, were conducted and presented. The calculated keff eigenvalues based on the four data libraries generally agree well with the benchmark evaluations for most cases. Among the 116 criticality benchmarks, the numbers of the calculated keff eigenvalues which agree with the benchmark evaluations within 3σ interval (with a confidence level of 99.6%) are 107, 109, 112, and 113 for ENDF/B-VII.0, ENDF/B-VII.1, ENDF/B-VIII.0 and JEFF-3.3, respectively. The present results indicate that the ENDF/B-VIII.0 neutron data library has a better performance on average.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.3
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• pp.51-57
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• 2010

A dual-mode direct conversion receiver is developed in $0.13\;{\mu}m$ RF CMOS process for IEEE 802.11n based wireless LAN and IEEE 802.16e based mobile WiMAX application. The RF receiver covers the frequency band between 2.3 and 2.7 GHz. Three-step gain control is realized in LNA by using current steering technique. Current bleeding technique is applied to the down-conversion mixer in order to lower the flicker noise. A frequency divide-by-2 circuit is included in the receiver for LO I/Q differential signal generation. The receiver consumes 56 mA at 1.4 V supply voltage including all LO buffers. Measured results show a power gain of 32 dB, a noise figure of 4.8 dB, a output $P_{1dB}$ of +6 dBm over the entire band.