• Journal of the Microelectronics and Packaging Society
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• v.12 no.3 s.36
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• pp.197-205
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• 2005

Development of the packaging is one of the critical issues for commercialization of the RF-MEMS devices. RF MEMS package should be designed to have small size, hermetic protection, good RF performance and high reliability. In addition, packaging should be conducted at sufficiently low temperature. In this paper, a low temperature hermetic wafer level packaging scheme for the RF-MEMS devices is presented. For hermetic sealing, Au-Sn eutectic bonding technology at the temperature below $300{\times}C$ is used. Au-Sn multilayer metallization with a square loop of $70{\mu}m$ in width is performed. The electrical feed-through is achieved by the vertical through-hole via filled with electroplated Cu. The size of the MEMS Package is $1mm\times1mm\times700{\mu}m$. By applying $O_2$ plasma ashing and fabrication process optimization, we can achieve the void-free structure within the bonding interface as well as via hole. The shear strength and hermeticity of the package satisfy the requirements of MIL-STD-883F. Any organic gases or contamination are not observed inside the package. The total insertion loss for the packaging is 0.075 dB at 2 GHz. Furthermore, the robustness of the package is demonstrated by observing no performance degradation and physical damage of the package after several reliability tests.

• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.58-62
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• 2010

This paper presents the effects of RF performance parameters on the Galileo receiver design via simulation after reviewing the requirements of the Galileo receiver structure. At first, we considered the general requirements, structure and characteristics of the Galileo system. Then we designed the Galileo receiver focused on performance requirement of 16 dB C/N which is equal to 15 % Error Vector Magnitude(EVM) by using Advanced Design System(ADS) simulation program. In order to verify the function of Automatic Gain Control(AGC)), we measured the IF output power level by changing the input power level at the front - end of the receiver. We analyzed the performance degradation due to phase noise variations of Local Oscillator(LO) in the Galileo receiver through EVM when the minimum sensitivity level of -127 dBm is applied at the receiver. We also analyzed the performance degradation according to variable Analog-to-Digital Converter(ADC) bits within the Dynamic range, -92 ~ -139 dBm, which has been defined by gain range (-2.5 ~ +42.5 dB) in the AGC operation. The results clearly show that the performance of the Galileo receiver can be improved by increasing ADC bits and reducing Phase Noise of LO.

• Convergence Security Journal
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• v.7 no.1
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• pp.35-43
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• 2007

The object of this paper is to design a biomedical signal measure systems based on sensor networks for the patient, integrated with computing technology. Using a combination of zigbee RF, embedded hardware and software technologies, as it allows the healthcare center to receive the information on emergency situations and the ordinary state of the patients individually or simultaneously, the healthcare center can copy with quickly a state of emergency and assist the normal life of the patient. In order to meet the low power and other requirements for the proposed system, we introduce a zigbee based RP which is the most suitable solution for improving the performance of our beeper system.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2055-2057
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• 2004

The Ku band that has been using for the satellite communication and broadcasting would be changed to K/Ka bands. The satellite system requires the antenna structure to fabricate low loss and small antenna that is able to be integrated with other Rf circuits for both Rx and Tx. So we should design it with dual feed antennas at K/Ka bands, high isolation between two different feeds and broadband circular polarization. This paper proposes the LTCC(Low Temperature Co-fired Ceramic) process for integration with other Rf circuits and the Axial mode of the helical antenna to satisfy those requirements.

• Information and Communications Magazine
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• v.19 no.9
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• pp.77-85
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• 2002

In this paper, we introduce an ADSRC(hdvanced DSRC) OFDM packet communication system which has been developed by ETRI. The ADSRC system is targeted to provide high terminal mobility, high data rate and seamless service in roadside environment for mobile office services. We discuss the requirements of the ADSRC communication system for mobile office services, and the system design specification to meet them with regard to air interface. The ADSRC packet communication systems consist of the MAC processor block, the OFDM packet modem block and the RF block. The MAC processor block handles medium access control and the test. The OFDM packet modem transmits data packets at up to 24Mbps adaptively and recovers the data from RF block. We describe the ADSRC packet communication system architecture and the ADSRC system protocol.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.4
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• pp.47-52
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• 1998

As to power combining system, it is very important to achieve a high combining efficiency in order to minimize theamount of prime power needed and hence the cooling requirements, all of which translate into reduced cost. The combining efficiency is degraded in practice by variation in the amplitude and phase of the signals to be combined. In this paper, the new power combining newtork is proposed and realized which has the automatic gain and phase control system. This control system makes amplituede and phase variation of its all path equal. When the amplitude and phase variations are within 0~5dB and .+-.50.deg., the results show that high combining efficiency is maintained.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1054-1060
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• 2010

LRT(Light Rail Transit) is currently adopting a more upgraded signal system these days. This latest signal system is a train on-board signal system with moving block based on the realtime bi-directional wireless communications. The system applies RF-CBTC(Radio Frequency - Communication Based Train Control System) in order th execute fully automated manless operation. This paper reviews the performance requirements and safety of RF-CBTC that will be applied to the fully automated manless operation for LRT.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.9
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• pp.481-487
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• 2004

The Ku band that has been using for the satellite communication and broadcasting would be changed to K/Ka bands. The satellite system requires the antenna structure to fabricate low loss and small antenna that is able to be integrated with other Rf circuits for both Rx and Tx. So we should design it with dual feed antennas at K/Ka bands, high isolation between two different feeds and broadband circular polarization. This paper proposes the LTCC(Low Temperature Co-fired Ceramic) process for integration with other Rf circuits and the Axial mode of the helical antenna to satisfy those requirements.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.117-125
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• 2004

The three-dimensional precision measurement technology for industrial product of middle and/or large scale has been developed. Theodolite measurement system which is one of the technology is widely used in aerospace industry. This paper describes a range alignment method of parabolic antenna to RF probe in the near field range by using the theodolite system. The range alignment of the Ku-band and Ka-band antennas has been accomplished within the requirements, ±1 mm and ±$0.05^{circ}$.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1776-1778
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• 2000

The demands placed on portable wireless communication equipment include low cost, low supply voltage, low power, dissipation, low noise, high frequency of operation, and low distortion. These design requirements cannot be met satisfactorily in many cases without the use of RF inductors. However, implementing the inductor on-chip has been regarded as an impractical task because of excessive substrate capacitance and substantial resistive losses due to metallization and the conductive silicon substrate. Hence, there is a great incentive to design, optimize, and model spiral inductors on Si substrate. So, we analyzed a chip inductors using electromagnetic analysis and established a set of design rules for rectangular spiral inductors.