• Journal of Biomedical Engineering Research
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• v.20 no.2
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• pp.205-212
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• 1999

When we want to observe and record a patient's EEG in an operating room, the operation of electrosurgical unit(ESU) causes undesirable artifacts with high frequency and high voltage. These artifacts make the amplifiers of the conventional EEG system saturated and prevent the system from measuring the EEG signal. This paper describes a high-performance bipolar EEG amplifier for a CSA (compressed spectral array ) system with reduced ESU artifacts. The designed EEG amplifier uses a balanced filter to reduce the ESU artifacts, and isolates the power supply and the signal source of the preamplifier from the ground to cut off the current from the ESU to the amplifier ground. To cancel the common mode noise in high frequency, a high CMRR(common mode rejection ratio) diffferential amplifier is used. Since the developed bipolar EEG amplifier shows high gain, low noise, high CMRR, high input impedance, and low thermal drift, it is possible to observe and record more clean EEG signals in spite of ESU operation. Therefore the amplifier may be applicable to a high-fidelity CSA system.

• Journal of Sensor Science and Technology
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• v.7 no.5
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• pp.300-305
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• 1998

In this paper, integrated pressure sensor with calibration of offset voltage and full scale output and temperature compensation of offset voltage and full scale output were designed. The signal conditioning circuitry are designed that calibrate the offset voltage and full scale output to desired values and minimize the temperature drift of offset voltage and full scale output. Designed circuits are simulated using SPICE in a bipolar technology. The ion implanted resistor of different temperature coefficient were used to trimming the desired values. As a results, offset voltage was calibrated to 0.133V and the temperature drift of offset voltage was reduced to $42\;ppm/^{\circ}C$. Also, the full scale output was calibrated to 4.65V and the temperature coefficient of full scale output was reduced to $40ppm/^{\circ}C$ after temperature compensation.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.385-385
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• 2012

A two terminal N+/P/N+ junction device to replace the conventional selective transistor was studied as a bilateral switching device for spin transfer torque (STT) MRAM based on 3D device simulation. An N+/P/N+ junction structure with $30{\times}30nm$ area requires bi-directional current flow enough to write a data by a drain induced barrier lowering (DIBL) under a reverse bias at N+/P (or P/N+ junction), and high current on/off ratio of 106. The SiGe materials are widely used in hetero-junction bipolar transistors, bipolar compensation metal-oxide semiconductors (BiCMOS) since the band gap of SiGe materials can be controlled by changing the fraction and the strain epilayers, and the drift mobility is increased with the increasing Ge content. In this work, N+/P/N+ SiGe material based junction provides that drive current is increased from 40 to $130{\mu}A$ by increased Ge content from 10~80%. When Ge content is about 20%, the drive current density of SiGe device substantially increased to 2~3 times better than Si-based junction device in case of 28 nm P length, which is sufficient current to operation of STT-MRAM.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.3
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• pp.161-166
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• 1999

We investigate the device characteristics of the separated shorted-anode LIGBT (SSA-LIGBT), which suppresses effectively the negative differential resistance regime, by 2-dimensional numerical simulation. The SSA-LIGBT increases the pinch resistance by employing the highly resistive n-drift region as an electron conduction path instead of the lowly resistive n buffer region of the conventional SA-LIGBT. The negative differential resistance regime of the SSA-LIGBT is significantly suppressed as compared with that of the conventional SA-LIGBT. The SSA-LIGBT shows the lower forward voltage drop than that of the conventional SA-LIGBT.

• Journal of Satellite, Information and Communications
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• v.8 no.2
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• pp.36-43
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• 2013

In this study, the high current behaviors and double snapback mechanism of gate grounded_extended drain n-type MOSFET(GG_EDNMOS) device were analyzed in order to realize the robust electrostatic discharge(ESD) protection performances of high voltage operating display driver IC(DDIC) chips. Both the transmission line pulse(TLP) data and the thermal incorporated 2-dimensional simulation analysis as a function of ion implant conditions demonstrate a characteristic double snapback phenomenon after triggering of bipolar junction transistor(BJT) operation. Also, the background carrier density is proven to be a critical factor to affect the high current behavior of the GG_EDNMOS devices.

• Journal of Digital Contents Society
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• v.18 no.6
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• pp.1193-1198
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• 2017

The IGBT structure developed in this paper is used as a high power switch semiconductor for DC transmission and distribution and it is expected that it will be used as an important electronic device for new and long distance DC transmission in the future by securing fast switching speed and improved breakdown voltage characteristic. As a new type of next generation power semiconductors, it is designed to improve the switching speed while at the same time improving the breakdown voltage characteristics, reducing power loss characteristics, and achieving high current density advantages at the same time. These improved properties were obtained by further introducing SiO2 into the N-drift region of the Planar IGBT and were compared and analyzed using the Sentaurus TCAD simulation tool.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.11
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• pp.981-986
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• 2008

The conventional IGBT has two problems to make the device taking high performance. The one is high on state voltage drop associated with JFET region, the other is low breakdown voltage associated with concentrating the electric field on the junction of between p base and n drift. This paper is about the structure to effectively improve both the lower on state voltage drop and the higher breakdown voltage than the conventional IGBT. For the fabrication of the circular trench IGBT with the circular trench layer, it is necessary to perform the only one wet oxidation step for the circular trench layer. Analysis on both the on state voltage drop and the breakdown voltage show the improved values compared to the conventional IGBT structure. Because the circular trench layer disperses electric field from the junction of between p base and n drift to circular trench, the breakdown voltage increase. The on state voltage drop decrease due to reduction of JFET region and direction changed of current path which pass through reversed layer channel. The electrical characteristics were studied by MEDICI simulation results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.4
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• pp.208-211
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• 2018

This paper details the design of a 1,200 V class trench gate field stop IGBT (insulated gate bipolar transistor) with a nano gate structure smaller than 1 um. Decreasing the size is important for lowering the cost and increasing the efficiency of power devices because they are high-voltage switching devices, unlike memory devices. Therefore, in this paper, we used a 2-D device and process simulations to maintain a gate width of less than 1 um, and carried out experiments to determine design and process parameters to optimize the core electrical characteristics, such as breakdown voltage and on-state voltage drop. As a result of these experiments, we obtained a wafer resistivity of $45{\Omega}{\cdot}cm$, a drift layer depth of more than 180 um, an N+ buffer resistivity of 0.08, and an N+ buffer thickness of 0.5 um, which are important for maintaining 1,200 V class IGBTs. Specially, it is more important to optimize the resistivity of the wafer than the depth of the drift layer to maintain a high breakdown voltage for these devices.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.5
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• pp.403-409
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• 2007

In this paper, effects of the trench angle($\theta$) on the breakdown voltage according to the process parameters of p-base region and doping concentrations of n-drift region in a Trench Gate IGBT (TIGBT) device were analyzed by computer simulation. Processes parameters used by variables are diffusion temperature, implant dose of p-base region and doping concentration of n-drift region, and aspects of breakdown voltage change with change of each parameter were examined. As diffusion temperature of the p-base region increases, depth of the p-base region increases and effect of the diffusion temperature on the breakdown voltage is very low in the case of small trench angle($45\;^{\circ}$) but that is increases 134.8 % in the case of high trench angle($90\;^{\circ}$). Moreover, as implant dose of the p-base region increases, doping concentration of the p-base region increases and effect of the implant dose on the breakdown voltage is very low in the case of small trench angle($45\;^{\circ}$) but that is increases 232.1 % in the case of high trench angle($90\;^{\circ}$). These phenomenons is why electric field concentrated in the trench is distributed to the p-base region as the diffusion temperature and implant dose of the p-base increase. However, effect of the doping concentration variation in the n-drift region on the breakdown voltage varies just 9.3 % as trench angle increases from $45\;^{\circ}$ to $90\;^{\circ}$. This is why magnitude of electric field concentrated in the trench changes, but direction of that doesn't change. In this paper, respective reasons were analyzed through the electric field concentration analysis by computer simulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.14-15
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• 2009

Insulated Gate Bipolar Transistor(IGBTs) are widely used in power device industry. However, to improve the breakdown voltage, IGBTs are suffered from increasing on-state voltage drop due to structural design. In this paper, the new structure is proposed to solve this problem. The proposed structure has double p-floating layer inserted in n-drift layer. The p-floating layers improve the breakdown voltage compared to conventional IGBT without change of other electrical characteristics such as on-state voltage drop and threshold voltage. this is because the p-floating layers expand electric field distribution at blocking state. A electrical characteristic of proposed structure is analyzed by using simulators such as TSUPREM and MEDICI. As a result, on-state voltage drop and threshold voltage are same to a conventional TIGBT, but breakdown voltage is improved to 16%.