• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.10
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• pp.91-97
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• 1998

The modulation performance of 10 Gbps electro-absorption InGaAsP/InGaAsP strain compensated MQW (Multiple Quantum Well) modulator module depends on the modulator as well as the package parasitics. The high frequency package parasitics resulting from various structural discontinuities, limit the modulation bandwidth and increase the chirp-parameter. Therefore, we propose the double bondwires embedded in dielectric materials to minimize the bondwire parasitics. Using the proposed structure with 50 $\Omega$ terminating resistor, the modulation bandwidth is greatly increased by 125 % than the bare chip and the chirp-parameter is also reduced. This technique can be used in optimizing the package of high speed external modulators.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.5
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• pp.54-61
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• 1999

We suggested a macro medel for MOS transistors, which incorporates the distributed substrate resistance by using a method which utilizes external diodes on SPICE MOS model. By fitting the simulated s-parameters to the measures ones, we obtained a model set for the W=200TEX>$\mu\textrm{m}$ and L=0.8TEX>$\mu\textrm{m}$ NMOS transistor, and also analyzed the effects of distributed substrate resistance in the RF range. By comparing the physical parameters calculated from simulated s-parameters such as ac resistances and capacitances with the measured ones, we confirmed the validity of the simulation results. For the frequencies below 10GHz, it seems appropriated to use a simple macro model which utilizes the existing SPICE MOS model with junction diodes, after including one lumped resistor each for gate and substrate nodes.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.286-292
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• 2014

This paper presents the parameters optimization technology for generating the first short stroke lightning current waveform($10/350{\mu}s$) which is necessary for the performance tests of components of lightning protection systems, as required under IEC 62305 and the newly amended IEC 62561. The circuit using the crowbar device specified in IEC 62305 was applied to generate the lightning current waveform. To find the proper parameters of the circuit is not easy because the circuit consists of two parts; circuit I, which relates to the front of current waveform, and circuit II, which relates to the tail. A simulation in PSpise was carried out to find main factors related to the front and tail of $10/350{\mu}s$. The lightning current generator was developed by utilizing the circuit parameters found in the simulation. In the result of experiments, new parameters of the circuits need to be changed because of the difference between the simulation and the experiment results. Using the iterative method, the optimized parameters of the circuits was determined. Also a multistage-type external coil and a damping resistor were proposed to make the efficiency of generation to enhance. According to the result in this paper, an optimized first short stroke lightning current waveform was obtained.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2577-2579
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• 2002

In this paper, we describe a CMOS DC-DC converter with a variable output voltage(8-12V @100mA) for a portable battery-operated system applications. The proposed DC-DC converter is used along with a Pulse-Frequency Modulation (PFM) method and consists of a reference circuit, a feedback resistor, a controller, and an internal oscillator. The integrated DC-DC converter with two external passive components(L.C) has been designed and fabricated on a 0.6${\mu}m$ 2-poly, 3-metal CMOS process and could be applied to the Personal Digital Assistants(PDA), Cellular Phone, Laptop Computer, etc.

• 전자공학회논문지 IE
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• v.47 no.3
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• pp.14-18
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• 2010

In this paper, we describe a CMOS DC-DC converter with a variable output voltage(5-7V @100mA) for a portable battery-operated system applications. The proposed DC-DC converter is used along with a Pulse-Frequency Modulation (PFM) method and consists of reference circuit, a feedback resistor, a controller, and an internal oscillator. The integrated DC-DC converter with two external passive components(L,C) has been designed and fabricated on a 0.5um 2-poly 3-metal CMOS process and could be applied to the Personal Digital Assistants(PDA), cellular Phone, Laptop Computer, etc.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1275-1282
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• 2012

This paper proposes the 16-channel LED Driver IC for Full color LED display system. The proposed LED driver IC in this paper can draw current independent of temperature and supply voltage in each channel. Current flow in the channel is configurable via an external resistor. LED brightness is adjusted by 12-Bit PWM(Pulse Width Modulation) and 8-Bit DC(Dot Correction). A real-time monitoring of IC temperature ($130^{\circ}C/150^{\circ}C$) and LED status (open/short) is provided by LED driver IC and the user can receive warning and get information on problems. A 16-channel LED driver IC is produced using 0.35 um BCD process and the size is $2.5mm{\times}2.5mm$. In this paper, channel current characteristic and channel current control function were measured in order to verify am embodied 16-channel LED driver IC by producing a single IC test board.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.4
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• pp.602-610
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• 1993

The DDA of new active element and the DDA differential integrator are designed. The DDA can be improved matching problems of external elements in op-amp application circuits. The design of DDA is used the transconductance element, differential pair and $2{\mu}m$ design rule. In order to evaluate the performance of the CMOS DDA, we simulated the DDA voltage inverter and the DDA level shifter using the designed CMOS DDA. Furthermore, the grounded resistor and the differential integrator is designed using the CMOS DDA and we found that its characteristics are agreed to OP-AMP differential integrator's. We performed the layout of the CMOS DDA and DDA differential integrator with MOSIS $2{\mu}m$ CMOS technology.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.5
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• pp.422-426
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• 2011

Piezoelectric materials can be used to convert mechanical energy into electrical energy. In this study, we investigated the possibility of harvesting from mechanical vibration force using a high efficient piezoelectric material-polyvinylidene fluoride (PVDF). A piezoelectric energy harvesting system consists of rectifier, filter capacitor, resistance. The experiments were carried out with impacting force to PVDF film with the thickness of 1 ${\mu}m$. The output power was measured with change in the load resistance value from 100 ${\Omega}$ to 2.2 $M{\Omega}$. The highest power was obtained under optimization by selection of suitable resistive load and capacitance. A power of 0.3082 ${\mu}W/mm^2$ was generated at the external vibration force of 5 N (10 Hz) across a 1 $M{\Omega}$ optimal resistor. Also, the maximum power of 0.345 ${\mu}W/mm^2$ was generated at 22 ${\mu}F$ and 1 $M{\Omega}$. The developed system was expected at a solution to overcome the critical problem of making up small size energy harvester.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.86-88
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• 1997

The detection of the normal zones in the coil winding and the initiation of the proper dump sequence have been one of the most important areas in the superconducting magnet technology. In this paper, the process to derive optimal dump sequence has been investigated through quench simulation and analysis of magnetically coupled superconducting magnet system. The magnet terminal voltage and maximum temperature rise in the quench initiated point are calculated with respect to various input variables such as operation current, dump resistance, etc. The experimental system is comprised of sc solenoidal coil, data aquisition device, external circuit breakers and dump resistor. The quench behavior of the magnet(e.g., temperature profile and the voltage signal) was measured. From this results, theoretical predictions were found to coincide with the experimental observations.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.174-174
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• 2014

Memristor devices are one of the most promising candidate approaches to next-generation memory technologies. Memristive switching phenomena usually rely on repeated electrical resistive switching between non-volatile resistance states in an active material under the application of an electrical stimulus, such as a voltage or current. Recent reports have explored the use of variety of external operating parameters, such as the modulation of an applied magnetic field, temperature, or illumination conditions to activate changes in the memristive switching behaviors. Among these possible choices of signal controlling factors of memristor, photon is particularly attractive because photonic signals are not only easier to reach directly over long distances than electrical signal, but they also efficiently manage the interactions between logic devices without any signal interference. Furthermore, due to the inherent wave characteristics of photons, the facile manipulation of the light ray enables incident light angle controlled memristive switching. So that, in the tautological sense, device orienting position with regard to a photon source determines the occurrence of memristive switching as well. To demonstrate this position controlled memory device functionality, we have fabricated a metal-semiconductor-metal memristive switching nanodevice using ZnO nanorods. Superhydrophobicity employed in this memristor gives rise to illumination direction selectivity as an extra controlling parameter which is important feature in emerging. When light irradiates from a point source in water to the surface treated device, refraction of light ray takes place at the water/air interface because of the optical density differences in two media (water/air). When incident light travels through a higher refractive index medium (water; n=1.33) to lower one (air; n=1), a total reflection occurs for incidence angles over the critical value. Thus, when we watch the submerged NW arrays at the view angles over the critical angle, a mirror-like surface is observed due to the presence of air pocket layer. From this processes, the reversible switching characteristics were verified by modulating the light incident angle between the resistor and memristor.