• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.3
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• pp.193-197
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• 2013

This paper presents a 5-bit true time delay circuit using a standard 0.18 ${\mu}m$ CMOS process for the broadband phased array antenna without the beam squint. The maximum time delay of ~106 ps with the delay step of ~3.3 ps is achieved at 5-20 GHz. The RMS group delay and amplitude errors are < 1 ps and <2 dB, respectively. The measured insertion loss is <27 dB and the input and output return losses are <12 dB at 5-15 GHz. The current consumption is nearly zero with 1.8 V supply. The chip size is $1.04{\times}0.85\;mm^2$ including pads.

• Journal of Sensor Science and Technology
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• v.26 no.6
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• pp.386-390
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• 2017

A $5^{th}$-order low-pass filter (LPF) chip implemented in a six-layer low-temperature co-fired ceramic (LTCC) dielectric substrate has been presented. Lumped elements constituting the LPF are designed three-dimensionally in multilayers. In order to improve the parasitic and mutual coupling effects between them, the LPF is designed by sequentially integrating the three-dimensional (3D) lumped elements, by comparing it to the results of the schematic circuit and 3D electromagnetic (EM) analysis. The designed 3D LPF chip was fabricated in a six-layer LTCC substrate as small as $4.0{\times}3.22{\times}0.68mm^3$. The measured return and insertion losses are less than -11 dB and -0.61 dB, respectively, below 1.5 GHz.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.197-202
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• 2001

The compressor is one of major noise sources in air conditioner outdoor units, especially deteriorating the sound quality. Therefore, the sound insulation materials layered with sound absorption materials are applied around compressors. In this study, the performance of the sound insulators is examined by measuring the insertion losses in power base and the effects of sound absorption materials, method of application and the shape of the insulators are also investigated. The importance of minimizing the opening is revealed well.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1355-1359
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• 2000

In this study, the insertion losses of various track-side railway noise barriers are analyzed by using a two-dimensional numerical boundary element method(BEM). The BEM is implemented using two out-of-phase monopole sources for each track to represent dipole source. All model for this study is based on actual size built in Test Line of KTX. And the results suggest that vertical absorptive barrier provide as effective screening as rigid barrier which is more 0.4 m than the height of those.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.208-211
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• 2006

In this paper, a tunable image rejection filter using two varactors is developed for mobile convergence. The filter is fabricated on a 0.25um substrate. ESD Pad is embedded to prevent damage caused by electrostatic discharge(ESD). Bias voltages are at WCDMA(2.1GHz). WiBro(2.3GHz), and WLAN(2.45) are 0.5V, 0.95V and 1.8V respectively. And the image rejection rations are more than 28dB at each band and insertion losses are less than 2dB at each band.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.570-572
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• 2012

In this paper, a three-dimensional (3-D) low-loss and wide-band BPF based on low-temperature co-fired ceramic (LTCC) has been presented for mm-wave wireless communication applications. The proposed BPF is designed in a 6-layer LTCC substrate. The double patch resonators are fully integrated into the LTCC dielectrics and vertical via and planar CPW transitions are designed for interconnection between embedded resonators and in/output ports and MMICs, respectively. The designed BPF was fabricated in a 6-layer LTCC dielectric. The fabricated BPF shows a centre frequency (fc) of 53.23 GHz and a 3dB bandwidth of 14.01 % from 49.5 to 56.9 GHz (7.46 GHz). An insertion loss of -1.56 dB at fc and return losses below -10 dB are achieved. Its whole size is $4.7{\times}1.7{\times}0.684mm^3$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.244-245
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• 2005

This paper presents the performance of BALUN embedded in the LTCC substrate of ZigBee system which is one of the kind of wireless communication. The BALUN is used to make two signal which have 180$^{\circ}$ phase difference and 3dB power from one input signal. Therefore, this is 3-port network circuit. At the center frequency(915MHz), insertion losses were 3.1dB and 3.4dB, respectively. Also, the phase difference was 182$^{\circ}$. Its size is 2.1$\times$3.6mm. The Used materials were dupont9599 LTCC ceramic and daejuo086 Ag.

• ETRI Journal
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• v.27 no.6
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• pp.677-684
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• 2005

A phased array antenna was fabricated using four-element ferroelectric phase shifters with a coplanar waveguide (CPW) transmission line structure based on a $Ba_{0.6}Sr_{0.4}TiO_3(BST)/MgO$ structure. Epitaxial BST films were deposited on MgO (001) substrates by pulsed laser deposition. To attain the large differential phase shift and small losses for a ferroelectric CPW phase shifter, an impedance-matching-part adding technique between the effective transmission line and connecting cable was used. The return loss and insertion loss for this techniqueadapted BST CPW device were improved with respect to those for a normal BST CPW device. For an X-band phased array antenna system consisting of ferroelectric BST CPW phase shifters, power divider, dc block, patch antenna, and programmed dc power, the steering beam could be tilted by $15^{\circ}$ in either direction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.71-72
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• 2008

In this paper, the effect of thermal annealing on surface acoustic wave (SAW) properties of aluminum nitride (AlN) films were described. The films were fabricated on Si substrates by using Pulsed Reactive Magnetron Sputtering System. The SAW properties of $600^{\circ}C$-annealed AlN films were better than those of both $900^{\circ}C$-annealed AlN films and as-deposited ones. Their SAW velocities (Raleigh mode) and insertion losses were about 5212 m/s and 16.19 dB at $600^{\circ}C$ with the wavelength of $40{\mu}m$. The dependence of characteristics of AlN films on annealing conditions were also evaluated by using Fourier Transform-Infrared Spectroscopy (FT-IR) Spectrums and Atomic Force Microscopy (AFM).

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.201-204
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• 2007

In this paper, fully embedded and miniaturized diplexer device has been developed and characterized for dual-band/mode CDMA handset applications. The size of the embedded diplexer is significantly reduced by embedding high Q circular spiral inductors and high DK MIM capacitors into a low cost organic package substrate. The fabricated diplexer has insertion losses and isolations of -0.5 and -23 dB at 824-894 MHz and -0.7 and -22 dB at 1850-1990 MHz, respectively. Its size is $3.9mm{\times}3.9mm{\times}0.77mm$. The fabricated diplexer is the smallest one which is fully embedded into a low cost organic package substrate.