• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.255-266
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• 2015

In this paper, a low-complexity and low-power soft output multiple input multiple output (MIMO) symbol detector is proposed for mobile devices with two transmit and two receive antennas. The proposed symbol detector can support both the spatial multiplexing mode and spatial diversity mode in single hardware and shows the optimal maximum likelihood (ML) performance. By applying a multi-stage pipeline structure and using a complex multiplier based on the polar-coordinate, the complexity of the proposed architecture is dramatically decreased. Also, by applying a clock-gating scheme to the internal modules for MIMO modes, the power consumption is also reduced. The proposed symbol detector was designed using a hardware description language (HDL) and implemented using a 65nm CMOS standard cell library. With the proposed architecture, the proposed MIMO detector takes up an area of approximately $0.31mm^2$ with 183K equivalent gates and achieves a 150Mbps throughput. Also, the power estimation results show that the proposed MIMO detector can reduce the power consumption by a maximum of 85% for the various test cases.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1210-1215
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• 2012

Traction motors for driving and power conversion devices using semiconductor switch are equipped with a transportation systems such as an electrical railway system. Power conversion devices have the possibility of malfunction by external electromagnetic waves. As a result, these could affect the safe operation of the railway. Moreover, the electromagnetic waves above safe limits will be harmful to the passengers inside the railway vehicles or anyone working around the rail-track. For this reason, the importance and need about the reliability check and complement of electromagnetic waves generated from the IPT(Inductive Power Transfer) system have been suggested for the safe application of the IPT system to the railway system. In this study, prediction for the electromagnetic wave properties was conducted through FEM(Finite Element Method) analysis of 5kW-class IPT system design model. Next, the 5kW IPT system prototype was made and then the small-scaled railway vehicle was made to mount the IPT system and the energy management system. Finally, the electromagnetic waves generated from the real small-scaled IPT system were measured and analyzed, and then the reliability check of predictions by FEM analysis were carried out.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.3
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• pp.204-212
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• 2020

In this study, device suitability analysis is performed by comparing the performance of SiC MOSFET and GaN Transistor, which are WBG power semiconductor devices in the induction heating (IH) system. WBG devices have the advantages of low conduction resistance, switching losses, and fast switching due to their excellent physical properties, which can achieve high output power and efficiency in IH systems. In this study, SiC and GaN are applied to a general half-bridge series resonant converter topology to compare the conduction loss, switching loss, reverse conduction loss, and thermal performance of the device in consideration of device characteristics and circuit conditions. On this basis, device suitability in the IH system is analyzed. A half-bridge series resonant converter prototype using the SiC and GaN of a 650-V rating is constructed to verify device suitability through performance comparison and verified through an experimental comparison of power loss and thermal performance.

• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.509-514
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• 2003

Mach-Zehnder interferometric wavelength converters with monolithically integrated semiconductor optical amplifiers (SOA's) have been fabricated and characteristics of wavelength conversion at 10 Gb/s have been investigated for wavelength span of 40 nm. The devices have been achieved by using a butt-joint combination of buried ridge structure type SOA's and passive waveguides. In the integration, a new method has been applied that removes p+InP cladding layer leading to high propagation loss and forms simultaneously the current blocking and the cladding layer using undoped InP. The module packaging has been achieved by using a titled fiber array for effective coupling into the tilted waveguide in the wavelength converter. Using the module, wavelength conversion with power penalty lower than 1 ㏈ at 10 Gb/s has been demonstrated for wavelength span of 40 nm. In addition, it is show that the module can provide 2R (re-amplification, re-shaping) operation by demonstrating the conversion with the negative penalty.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.4
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• pp.270-275
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• 2012

Power MOSFET(metal oxide silicon field effect transistor) operate voltage-driven devices, design to control the large power switching device for power supply, converter, motor control, etc. But on-resistance characteristics depending on the increasing breakdown voltage spikes is a problem. So 600 V planar power MOSFET compare to 1/3 low on-resistance characteristics of super junction MOSFET structure. In this paper design to 600 V planar MOSFET and super junction MOSFET, then improvement of comparative analysis breakdown voltage and resistance characteristics. As a result, super junction MOSFET improve on about 40% on-state voltage drop performance than planar MOSFET.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.184-188
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• 1999

The power semiconductor switching devices(PSSD) continuously developed, Power Electronic Technology using PSSD is gradually extended. The high frequency inverter to generate the large power high frequency subject to power electronic technology pursuit various applications. Also, in emboss with environmental destruction problem cause the atmosphere and the water pollution to growth of the commercial society, the research in favor of cleaning environmental a pollutant actively proceed. Therefore, This paper describe study on the high frequency pulse power supply. The theoretical results are in good agreement with the experimental ones. The proposed pulse power supply is considerated to be useful for discharge lamp.

• Journal of Power Electronics
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• v.9 no.1
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• pp.36-42
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• 2009

This paper presents a review of an improved high power-high frequency III-V wide bandgap (WBG) semiconductor device, Gallium Nitride (GaN). The device offers better efficiency and thermal management with higher switching frequency. By having higher blocking voltage, GaN can be used for high voltage applications. In addition, the weight and size of passive components on the printed circuit board can be reduced substantially when operating at high frequency. With proper management of thermal and gate drive design, the GaN power converter is expected to generate higher power density with lower stress compared to its counterparts, Silicon (Si) devices. The main contribution of this work is to provide additional information to young researchers in exploring new approaches based on the device's capability and characteristics in applications using the GaN power converter design.

• Journal of Power Electronics
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• v.15 no.4
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• pp.951-963
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• 2015

In this paper, a new symmetric multilevel inverter is proposed. A simple structure for the cascaded multilevel inverter topology is also proposed, which produces a high number of levels with the application of few power electronic devices. The symmetric multilevel inverter can generate 2n+1 levels with a reduced number of power switches. The basic unit is composed of a single and double source unit (SDS-unit). The application of this SDS-unit is for reducing the number of power electronic components like insulated gate bipolar transistors, freewheeling diodes, gate driver circuits, dc voltage sources, and blocked voltages by switches. Various new algorithms are recommended to determine the magnitude of dc sources in a cascaded structure. Furthermore, the proposed topology is optimized for different goals. The proposed cascaded structure is compared with other similar topologies. For verifying the performance of the proposed basic symmetric and cascaded structure, results from a computer-based MATLAB/Simulink simulation and from experimental hardware are also discussed.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.216-225
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• 2006

This paper presents a new circuit topology of DC busline switch and snubbing capacitor-assisted full-bridge soft-switching PWM inverter type DC-DC power converter with a high frequency link for low voltage large current applications as DC feeding systems, telecommunication power plants, automotive DC bus converters, plasma generator, electro plating plants, fuel cell interfaced power conditioner and arc welding power supplies. The proposed power converter circuit is based upon a voltage source-fed H type full-bridge high frequency PWM inverter with a high frequency transformer link. The conventional type high frequency inverter circuit is modified by adding a single power semiconductor switching device in series with DC rail and snubbing lossless capacitor in parallel with the inverter bridge legs. All the active power switches in the full-bridge inverter arms and DC busline can achieve ZVS/ZVT turn-off and ZCS turn-on commutation operation. Therefore, the total switching losses at turn-off and turn-on switching transitions of these power semiconductor devices can be reduced even in the high switching frequency bands ranging from 20 kHz to 100 kHz. The switching frequency of this DC-DC power converter using IGBT power modules is selected to be 60 kHz. It is proved experimentally by the power loss analysis that the more the switching frequency increases, the more the proposed DC-DC converter can achieve high performance, lighter in weight, lower power losses and miniaturization in size as compared to the conventional hard switching one. The principle of operation, operation modes, practical and inherent effectiveness of this novel DC-DC power converter topology is proved for a low voltage and large current DC-DC power supplies of arc welder applications in industry.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.491-491
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• 2011

Transparent and flexible electronic devices that are light-weight, unbreakable, low power consumption, optically transparent, and mechanical flexible possibly have great potential in new applications of digital gadgets. Potential applications include transparent displays, heads-up display, sensor, and artificial skin. Recent reports on transparent and flexible field-effect transistors (tf-FETs) have focused on improving mechanical properties, optical transmittance, and performances. Most of tf-FET devices were fabricated with transparent oxide semiconductors which mechanical flexibility is limited. And, there have been no reports of transparent and flexible all-organic tf-FETs fabricated with organic semiconductor channel, gate dielectric, gate electrode, source/drain electrode, and encapsulation for sensor applications. We present the first demonstration of transparent, flexible all-organic sensor based on multifunctional organic FETs with organic semiconductor channel, gate dielectric, and electrodes having a capability of sensing infrared (IR) radiation and mechanical strain. The key component of our device design is to integrate the poly(vinylidene fluoride-triflouroethylene) (P(VDF-TrFE) co-polymer directly into transparent and flexible OFETs as a multi-functional dielectric layer, which has both piezoelectric and pyroelectric properties. The P(VDF-TrFE) co-polumer gate dielectric has a high sensitivity to the wavelength regime over 800 nm. In particular, wavelength variations of P(VDF-TrFE) molecules coincide with wavelength range of IR radiation from human body (7000 nm ~14000 nm) so that the devices are highly sensitive with IR radiation of human body. Devices were examined by measuring IR light response at different powers. After that, we continued to measure IR response under various bending radius. AC (alternating current) gate biasing method was used to separate the response of direct pyroelectric gate dielectric and other electrical parameters such as mobility, capacitance, and contact resistance. Experiment results demonstrate that the tf-OTFT with high sensitivity to IR radiation can be applied for IR sensors.