• Journal of electromagnetic engineering and science
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• v.18 no.2
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• pp.78-87
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• 2018

This paper describes specular reflectance measurements of dielectric plates in three waveguide frequency bands: D-band (110-170 GHz), G-band (140-220 GHz), and J-band (220-325 GHz). The transmit (Tx) part of the proposed specular reflectance measurement system is stationary, while the receive (Rx) part and the material under test (MUT) holder are concentric-rotating with a 2:1 speed ratio for specular reflectance measurements. In specular reflectance measurements, the first step measures the specular reflection coefficients of an MUT and a metal plate on the MUT holder located at the center of the Tx and Rx parts, and the second step calculates the specular reflectance defined by the specular reflection power (i.e., intensity) of the MUT normalized to that of the metal plate. Multiple reflection effects between the Tx and Rx antennas and the MUT on the measured specular reflectance are minimized by averaging out the multiple specular reflectances measured with changing the separation distance between the two antennas by ${\lambda}/8$ intervals. Measurement results of the perpendicular-polarized specular reflectance of commonly used dielectric plates are verified by comparing those with the analytic results and show that the results measured over the overlapped frequency range of the D-/G-bands and at the boundary frequency of the G-/J-bands agree well with the results for the other band, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2697-2702
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• 2014

In this paper, we demonstrated a Ku-band 2W MMIC power amplifier for satellite communication applications. The device technology used relies on $0.25{\mu}m$ GaAs pseudomorphic high electron mobility transistor (PHEMT) of Wireless Information Networking (WIN) Semiconductor foundry. The 2W MMIC power amplifier has gain of over 29 dB and saturation output power of over 33.4 dBm in the frequency range of 13.75 ~ 14.5 GHz. Power added efficiency (PAE) is a 29 %. To our knowledge, this is the highest power added efficiency reported for any commercial GaAs-based 2W MMIC power amplifier in the Ku-band.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.159-162
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• 1999

In this paper, we have designed and fabricated a MMIC power amplifier for X-band using AlGaAs/InGaAs/GaAs PM-HEMTs and passive devices such as Ti thin film resistors, rectangular spiral inductors and MIM capacitors. The fabricated MMIC power amplifier for X-band shows that S/ sub 21/ and S$_{11}$ are 14.804 ㏈ and -29.577 at 8.18 GHz, respectively. The chip size is 1.86$\times$1.29 $\textrm{mm}^2$.>.>.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.2
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• pp.267-276
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• 1999

A 2 stage 6-pole bandpass filter (BPF) is designed and implemented by using K-band triple-mode cavity. The BPF has an 100MHz bandwidth at the center frequency of 18.5GHz and the response of the filter is Chebyshev function. The cavity filter uses two orthogonal $TE_{113}$ modes and one $TM_{012}$ mode. To obtain a Chebyshev response, the intercavity coupling between the adjacent cavities is accomplished by H-field component of TE modes parallel to slot plate. In this paper, the size and location of intercavity slot are determined by the detailed coupling equation from H-field of TE resonant modes in circular cavity. The measured results agree well with the theoretical one.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.327-332
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• 2017

As Internet of Things (IoT) technology advances, there is a growing demand for location-based services (LBSs) to identify users' mobility and identity. The initial LBS system was mainly used to measure position information by measuring the phase of a signal transmitted from a global positioning system (GPS) satellite or by measuring distance to a satellite by tracking the code of a carrier signal. However, the use of GPS satellites is ineffective, because it is difficult to receive satellite signals indoors. Therefore, research on wireless communications systems like ultra-wide band (UWB), radio frequency identification (RFID), and ZigBee are being actively pursued for location recognition technology that can be utilized in an indoor environment. In this paper, we propose an LBS system that includes the 2.45GHz band for chirp spread spectrum (CSS), and the 3.1-10.6GHz band and the 250-750MHz bands for UWB using the IEEE 802.15.4a standard for low power-based location recognition. As a result, we confirmed that the 2.45GHz Industrial, Scientific and Medical (ISM) band RF transceiver and the ranging function can be realized in the hardware and has 0dBm output power.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.116
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• pp.37-43
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• 2007

In this.paper, we introduce design and implementation results of the single balanced diode mixer for European point-to-point microwave radio in order to improve flatness performance. When a resonator such as RF filter is integrated with a mixer, impedance characteristic of 50 ohm is maintained only in RF band, not in LO band resulting deterioration of flatness performance because of LO power variation on the diode. In the paper, we suggest a design method of mixer integrated with image rejection filter and LO harmonic filter to have a better performance of flatness using embedding electrical length between filter and mixer's port. Frequency specification of fabricated mixer is $21.2{\sim}22.6\;GHz$ for RF, $19.32{\sim}20.72\;GHz$ for LO and 1.88 GHz+/-50 MHz for IF, respectively. Measured results show conversion loss of 8.5 dB, flatness of 2 dB, input PldB of 8 dBm, IIP3 of 15 dBm under LO power level of 10 dBm. Return losses of RF, LO and IF port are under -12 dB, -10 dB and -5 dB, respectively. Isolations of LO/RF and LO/IF are 20 dB and 50 dB, respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.9
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• pp.74-80
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• 2009

This paper describes a $2{\sim}6GHz$ CMOS frequency synthesizer that employs only one LC-tank voltage controlled oscillator (VCO). For wide-band operation, optimized LO signal generator is used. The LC-tank VCO oscillating in $6{\sim}8GHz$ provides the required LO frequency by dividing and mixing the VCO output clocks appropriately. The frequency synthesizer is based on a fractional-N phase locked loop (PLL) employing third-order 1-1-1 MASH type sigma-delta modulator. Implemented in a $0.18{\mu}m$ CMOS technology, the frequency synthesizer occupies the area of $0.92mm^2$ with of-chip loop filter and consumes 36mW from a 1.8V supply. The PLL is completed in less than $8{\mu}s$. The phase noise is -110dBC/Hz at 1MHz offset from the carrier.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.3
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• pp.330-333
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• 2016

In this paper, we propose 77 GHz power amplifier for long range automotive collision avoidance radar using 65 nm CMOS process. The proposed circuit has a 3-stage single power amplifier which includes common source structure and transformer. The measurement results show 18.7 dB maximum voltage gain at 13 GHz 3 dB bandwidth. The measured maximum output power is 10.2 dBm, input $P_{1dB}$ is -12 dBm, output $P_{1dB}$ is 5.7 dBm, and maximum power add efficiency is 7.2 %. The power amplifier consumes 140.4 mW DC power from 1.2 V supply voltage.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.4
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• pp.281-285
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• 2006

In order to widen the tuning range, capacitive degeneration is applied to fully CMOS LC VCOs. Small signal analysis shows that the fixed MOSFET capacitance seen by the LC tank is smaller than that of the traditional LC VCO, resulting in significant extension in the tuning range. This improvement in the tuning range has been verified through measurement of a 10-GHz LC VCO fabricated by $0.18{\mu}m$ CMOS process. The measured tuning range is from 9.8-GHz to 12-GHz, which is better than those of the reported CMOS LC VCOs in 10-GHz band. The measured phase noise is - 103dBc/Hz at 1MHz offset.

• Transactions on Electrical and Electronic Materials
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• v.18 no.2
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• pp.62-65
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• 2017

In this paper, three DC Block designs are presented which efficiently meet the need of modern-day compactsize wireless communication systems. As one of the important parts of a complete system design, the proposed microstrip-based DC block with coupled transmission lines efficiently attenuates unwanted frequencies that cause damage to the system. The compact-sized DC block structures are created by incorporating an extended coupled-line section with a radial stub, an enveloped coupled-line section, and using alternate up-down meandering techniques. The structures are analyzed for the L-Band using a high-resistive silicon substrate. At a resonating frequency of 1.575 GHz, the designed DC Block structures have a return loss better than -10 dB, an insertion loss of around -1 dB, and also possess wide pass-band characteristics.