• Transactions on Electrical and Electronic Materials
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• v.4 no.3
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• pp.5-9
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• 2003

In this paper, a layout-based CMOS RF model for RFIC's including the capacitance effect, the skin effect, and the proximity effect between metal lines on the Si surface is proposed for the first time for accurately predicting the RF behavior of CMOS devices. With these RF effects, the RF equivalent circuit model based on the layout of the multi-finger gate transistor is presented. The capacitances between metal lines on the Si surface are modeled with the layout. And the skin effect is modeled to the equivalent ladder circuit of metal line. The proximity effect is modeled by adding the mutual inductance between cross-coupled inductances in the ladder circuit representation. Compared to the BSIM 3v3 and other models, the proposed RF model shows better agreements with the measured data and shows well the frequency dependent behavior of devices in GHz ranges.

• ETRI Journal
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• v.31 no.6
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• pp.755-764
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• 2009

This paper presents a switched self-biasing and a tail current-shaping technique to suppress the 1/f noise from a tail current source in differential cross-coupled inductance-capacitance (LC) voltage-controlled oscillators (VCOs). The proposed LC VCO has an amplitude control characteristic due to the creation of negative feedback for the oscillation waveform amplitude. It is fabricated using a 0.13 ${\mu}m$ CMOS process. The measured phase noise is -117 dBc/Hz at a 1 MHz offset from a 4.85 GHz carrier frequency, while it draws 6.5 mA from a 0.6 V supply voltage. For frequency tuning, process variation, and temperature change, the amplitude change rate of the oscillation waveform in the proposed VCO is 2.1 to 3.2 times smaller than that of an existing VCO with a fixed bias. The measured amplitude change rate of the oscillation waveform for frequency tuning from 4.55 GHz to 5.04 GHz is 131 pV/Hz.

• Tribology and Lubricants
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• v.22 no.2
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• pp.99-104
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• 2006

The dielectric constants of fresh engine oils were obtained according to various types of oil, temperatures and frequencies. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constant of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated by cross capacitances measured by a sensor tube. Before finding the correlation, as a prerequisites study, the best condition measuring the dielectric constant was found. In general, it was found that the value of dielectric constant became stable below $60^{\circ}C$ regardless frequency variation. Further, above 6kHz, the dielectric constant became stable even if temperature had been above $100^{\circ}C$.

• Journal of the Korean institute of surface engineering
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• v.33 no.4
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• pp.217-221
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• 2000

The gate oxide thickness is becoming thinner and thinner in order to speed up the semiconductor CMOS devices. We have investigated very thin$ SiO_2$ gate oxide layers and found anomaly between the thickness determined with capacitance measurement and these obtained with cross-sectional high resolution transmission electron microscopy. The thicknesses difference of the two becomes important for the thickness of the oxide below 5nm. We propose that the variation of dielectric constant in thin oxide films cause the anomaly. We modeled the behavior as (equation omitted) and determined $\varepsilon_{bulk}$=3.9 and $\varepsilon_{int}$=-4.0. We predict that optimum $SiO_2$ gate oxide thickness may be $20\AA$ due to negative contribution of the interface dielectric constant. These new results have very important implication for designing the CMOS devices.s.

• Smart Structures and Systems
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• v.28 no.6
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• pp.839-853
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• 2021

In this paper, a novel multimode liquid metal-based pressure sensor is developed. The main body of the sensor is composed of polydimethylsiloxane (PDMS) elastomer. The structure of the sensor looks like a sandwich, in which the upper structure contains a cylindrical cavity, and the bottom structure contains a spiral microchannel, and the middle partition layer separates the upper and the bottom structures. Then, the liquid metal is injected into the top cavity and the bottom microchannel. Based on linear elastic fracture mechanics, the deformation of the microchannel cross-section is theoretically analyzed. The changes of resistance, capacitance, and inductance of the microchannel under pressure are deduced, and the corresponding theoretical models are established. The theoretical values of the pressure sensor are in good agreement with experimental data, implying that the developed theoretical model can explain the performance of the sensor well.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.311-316
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• 2015

This paper presents a design method for thin but wideband absorbers using resistive sheets. Its equivalent circuit consists of a series RLC resonant circuit and a short-terminated transmission line. Based on this equivalent circuit, we presented the three conditions for an electromagnetic absorber which has a thickness less than a quarter wavelength and wide absorption bandwidth at center frequency. By using an root-finding algorithm, the equivalent resistance, capacitance, and inductance of the absorbers are obtained. These equivalent circuit values for the absorber surface can be realized by a 2D periodic cross-shaped structure which has required surface resistance. Using the design method, we have designed the absorber which has 18.75 mm($67.5^{\circ}$ electrical length) thickness and 90 % absorption bandwidth of 116 % bandwidth at 3 GHz.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.71-71
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• 2012

As the critical dimensions of integrated circuits are scaled down, the line width and spacing between the metal interconnects are made smaller. The dielectric film used as insulation between the metal lines contributes to the resistance-capacitance (RC) time constant that governs the device speed. If the RC time delay, cross talk and lowering the power dissipation are to be reduced, the intermetal dielectric (IMD) films should have a low dielectric constant. The introduction of Cu and low-k dielectrics has incrementally improved the situation as compared to the conventional $Al/SiO_2$ technology by reducing both the resistivity and the capacitance between interconnects. Some of the potential candidate materials to be used as an ILD are organic and inorganic precursors such as hydrogensilsequioxane (HSQ), silsesquioxane (SSQ), methylsilsisequioxane (MSQ) and carbon doped silicon oxide (SiOCH), It has been shown that organic functional groups can dramatically decrease dielectric constant by increasing the free volume of films. Recently, various inorganic precursors have been used to prepare the SiOCH films. The k value of the material depends on the number of $CH_3$ groups built into the structure since they lower both polarity and density of the material by steric hindrance, which the replacement of Si-O bonds with Si-$CH_3$ (methyl group) bonds causes bulk porosity due to the formation of nano-sized voids within the silicon oxide matrix. In this talk, we will be introduce some properties of SiOC(-H) thin films deposited with the dimethyldimethoxysilane (DMDMS: $C_4H_{12}O_2Si$) and oxygen as precursors by using plasma-enhanced chemical vapor deposition with and without ultraviolet (UV) irradiation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.6 s.97
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• pp.594-602
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• 2005

In this paper, a new type of 5-pole low pass filter(LPF) having defected ground structure(DGS) and very wide transmission line elements is proposed. The previously presented design method of 3-stage LPF using DGS is generalized to design N-pole LPFs for $N\geq5$. As an example, a 5-pole LPF having DGS is designed and measured. The accurate curve-fitting method to determine the series inductors in the prototype filter, and ultimately the size of DGS is described. The proposed 5-pole LPF has transmission line elements with a very low impedance to realize the required shunt capacitance instead of open stubs. Therefore, open stub. Therefore, open stub, Tee-junction, Cross-junction, and high impedance line are not required for the proposed LPF, while they all have been essential in conventional LPFs.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.171-176
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• 2005

This study designed and fabricated a multi-purpose planar antenna for base stations that are accessible to DCS, WiBro, and ISM. The proposed antenna was designed into an open loop form from the existing monopole structure. The capacitance of the multi-purpose antenna was increased by the coupling of open parts. This makes the use of MMIC and LTCC convenient and the antenna is smaller and has a larger gain than existing antennas. The resonance distance and bandwidth can be adjusted by changing the open gap and the height of the loop of the antenna. The bandwidth of the designed antenna satisfies DCS, IMT-2000, WiBro, Bluetooth, wireless LAN and ISM bands based on VSWR 2. The entire frequency bandwidth is $58.75\%$ of $1.575GHz\~2.985GHz(1.41GHz)$. Also, the radiation pattern of the antenna displayed co-polarization and cross-polarization characteristics at 1.6GHz, 2.3GHz and 2.8GHz.

• Journal of Advanced Navigation Technology
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• v.25 no.1
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• pp.90-95
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• 2021

In this paper, the design method for a high-sensitivity compact resonator for chipless RFID tags is proposed. Proposed high-sensitivity compact resonator uses an interdigital-capacitor structure instead of a capacitor-shaped strip structure in a conventional ELC resonator. The length of the electrode plate of the IDC structure is longer than that of the conventional capacitor-shaped structure, resulting in a larger equivalent capacitance of the resonator. This can lower the resonant peak frequency of the RCS characteristic. Two resonators with the same length of the square loop and the width of the strip are fabricated on an RF-301 substrate with a thickness of 0.8 mm. The experiment results show that the resonant peak frequency and value of the bistatic RCS for the ELC resonator were 4.305 GHz and -30.39 dBsm, whereas those of the proposed IDC resonator were 3.295 GHz and -36.91 dBsm. Therefore, the size of the resonator is reduced by 23.5% based on the measured resonant peak frequency of the RCS characteristic.