• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.11
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• pp.89-94
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• 2007

For successful implementation of multi-standard transmitter, reconfigurable architecture and component design are essential. This paper presents a reconfigurable CMOS power amplifier designed CMOS 0.25 um process. Designed power amplifier can be operated at 0.9, 1.2, 1.75, and 1.85 GHz. Also, it can be used at 2.4 GHz by using bonding wire inductor. The interstage matching network is composed of two inductors and four switches, and operation frequency can be varied by controlling switches. Proposed power amplifier can be used as a power amplifier in low power applications such as ZigBee or Bluetooth application and used as a driver amplifier in high power application such as CDMA application. Designed power amplifier has 18.2 dB gain and 10.3 dBm output power at 0.9 GHz. Also, it represented 10.3 (18.1) dB gain and 5.2 (10) dBm output power at 1.75 (2.4) GHz.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.5
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• pp.21-26
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• 2014

This paper proposes a frequency reconfigurable antenna which operates at not only LTE but also other currently serviced bands. The high band(1,710-2,170 MHz) performance was satisfied through PIFA structure, and the low band performance through the additional RF Switch by changing the state between SW1 and SW2. When the RF switch is SW1 state, the operation bandwidth is 782-907 MHz (GSM), and 738-861 MHz (LTE) at OFF state. The proposed antenna has a omni-directional radiation pattern and measured peak gains were 0.04-4.68 dBi at the SW1 state and 0.92-1.53 dBi at the SW2 state, respectively. Judging from the results, proposed reconfigurable antenna is expected to be applied to LTE-Advanced mobile terminals since the antenna shows an outstanding performance.

• ETRI Journal
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• v.33 no.3
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• pp.326-334
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• 2011

This paper outlines the time jitter effect of a sampling clock on a software-defined radio technology-based digital intermediate frequency (IF) transceiver for a mobile communication base station. The implemented digital IF transceiver is reconfigurable to high-speed data packet access (HSDPA) and three bandwidth profiles: 1.75 MHz, 3.5 MHz, and 7 MHz, each incorporating the IEEE 802.16d worldwide interoperability for microwave access (WiMAX) standard. This paper examines the relationship between the signal-to-noise ratio (SNR) characteristics of a digital IF transceiver with an under-sampling scheme and the sampling jitter effect on a multichannel orthogonal frequency-division multiplexing (OFDM) signal. The simulation and experimental results show that the SNR of the OFDM system with narrower band profiles is more susceptible to sampling clock jitter than systems with relatively wider band profiles. Further, for systems with a comparable bandwidth, HSDPA outperforms WiMAX, for example, a 5 dB error vector magnitude improvement at 15 picoseconds time jitter for a bandwidth of WiMAX 3.5 MHz profile.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.129-129
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• 2009

In this paper, a tunable microstrip patch antenna designed using RF MEMS switches is reported. The design and simulation antenna were performed using high frequency structure simulator (HFSS). The antenna was designed in ISM Band and operates simultaneously at 2.4 GHz and 5.7 GHz with a -10 dB return-loss bandwidth of 20 MHz and 180 MHz, respect-tively. To obtain high efficiency and improve integrated ability, the High Resistivity Silicon (HRS) wafer was used for the antenna. The antenna achieved high gain with 8 dB at 5.7 GHzand 1.5 dB at 2.4 GHz. The RF MEMS DC contact switches was simulated and analysis by ANSYS software.

• Journal of Sensor Science and Technology
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• v.20 no.3
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• pp.145-150
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• 2011

In this paper, we designed a tunable microstrip patch antenna using RF MEMS switches. The design and simulation of the antenna were performed using a high frequency structure simulator(HFSS). The antenna was designed for use in the ISM band and either operates at 2.4 GHz or 5.7 GHz achieving -10 dB return-loss bandwidths of 20 MHz and 180 MHz, respectively. In order to obtain high efficiency and improve the ease of integration, a high resistivity silicon(HRS) wafer on a glass substrate was used for the antenna. The antenna achieved high gains: 8 dB at 5.7 GHz and 1 dB at 2.4 GHz. The RF MEMS DC contact switches were simulated and analyzed using ANSYS software.

• Journal of electromagnetic engineering and science
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• v.16 no.1
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• pp.29-34
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• 2016

This paper proposes a reconfigurable microstrip diplexer, also known as a switchplexer, for use with single-switch operation of frequency band and output path. The proposed switchplexer is composed of a rectangular ring resonator and a switch on a shorting pin, which is inserted between the ring resonator and the ground plane. The rotated main current distributions occurring at different switch statuses provide the diplexer's different operating bands and different output ports. The performance of the simply designed switchplexer is successfully demonstrated via simulation and measurement.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.142-144
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• 2019

Nowadays, multi-MHz wireless power transfer (WPT) system has received a great concern of study due to its desirable characteristics such as user convenience, system compact and better safety as compared to the conventional DC-DC with cord. This paper presents a solution for WPT Lithium Batteries charger with Constant Current (CC) and Constant Voltage (CV) charging process. The proposed system consists of a high frequency class D power amplifier, a pair of PCB coil, transformable high-order resonant network and a full-bridge rectifier. The charger can be implemented CC /CV charging profile thanks to automatic reconfigurable resonant compensator. Therefore, the battery can be fully charged without the help of an additional DC/DC converter. The simulation and 50W-6.78-MHz hardware experimental results are presented to verify the feasibility of the proposed method and to evaluate the performance of the proposed wireless battery charger.

• ETRI Journal
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• v.36 no.1
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• pp.151-154
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• 2014

A novel frequency-switchable antenna that uses PIN diodes and a composite right- and left-handed transmission line (CRLH TL) is proposed. The CRLH TL provides multi-order resonance, including a zeroth-order resonance (ZOR), and its shunt stub determines the ZOR frequency. Thus, the resonant frequency is arbitrarily chosen by lumped chip inductors on the shunt stub. Two prototypes are designed using different chip inductors while maintaining the antenna geometries. Antenna #1 can switch the resonant frequency from 1.8 GHz to 2.3 GHz. Antenna #2 can switch its resonance from 0.9 GHz to 2.3 GHz.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.682-685
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• 2014

In this paper, we presented the window applicable blind-type frequency selective surface to control the coverage area of wireless communication in secure building or conference room. The proposed frequency selective structure has the reconfigurable frequency range depends on its blind rotation angle. To verify the proposed structure, we fabricated the window blind-type frequency selective surface with four-legged loaded element and ring-type element as a unit cell and performed measurements of the transmission characteristics for different blind rotation angles to prove the feasibility. The measurement results show good agreements with the simulation results. One of the advantages is that the proposed structure does not need to have a bias circuit, so it is very easy to implement at low cost and also can be applied to any planar surface for wireless security applications.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.4
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• pp.63-72
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• 2007

In this paper, we propose a novel reconfigurable coprocessor for multimedia mobile terminals. Because most of multimedia operations require fast operations of large amount of data in the limited clock frequency, it is necessary to enhance the performance of the embedded processor that is widely used in current multimedia mobile terminals. Therefore, we proposed and have designed the coprocessor which had the ability of fast operations of multimedia data. The proposed coprocessor was not only reconfigurable, but also flexible and expandable. The proposed coprocessor has been designed by using VHDL and compared with previous reconfigurable coprocessors and a commercial embedded processor in architecture and speed. As a result of the architectural comparison, the proposed coprocessor had better structure in terms of hardware size and flexibility. Also, the simulation results of DCT application showed that the proposed coprocessor was 26 times faster than a commercial ARM processor and 11 times faster than the ARM processor with fast DCT core.