• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.4
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• pp.506-514
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• 1998

The design and fabrication of X-band(11.7~12 GHz) 2-stage monolithic microwave integrated circuit(MMIC) low noise amplifier (LNA) for active antenna are presented using $0.15{\mu}m\times140{\mu}m$ AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor (P-HEMT). In each stage of the LNA, a series feedback by using a source inductor is used for both input matching and good stability. The measurement results are achieved as an input return loss under -17 dB, an output return loss under -15dB, a noise figure of 1.3dB, and a gain of 17 dB at X-band. This results almost concur with a design results except noise figure(NF). The chip size of the MMIC LNA is $1.43\times1.27$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.4
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• pp.886-893
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• 2004

In this paper, active resonator oscillator using active band pass filter with gain, active resonator with negative resistance using transistor(agilent ATF-34143) is designed and fabricated. Proposed active resonator oscillator for local oscillator in ISM band(5.8GHz) is designed with 5.5 GHz oscillation frequency. Designed active resonator oscillator implemented on the substrate which has the relative dielectric constant of 3.38, the height of 0.508mm, and metal thickness of 0.018mm. Active resonator oscillators using active band pass filter with gain show the oscillation frequency of 5.6GHz with the output power of -2dBm and phase noise of -81dBc/Hz at the offset frequency of 100kHz. Active resonator oscillators active resonator with negative resistance show the oscillation frequency of 5.6, 5.8GHz with the output power of -4dBm and phase noise of -91dBc/Hz at the offset frequency of 100kHz.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.179-185
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• 2019

In this paper, we have studied narrow-band analog pre-distortion linearization technique using UHF 400 MHz band 20 W power amplifier. The analog pre-distorter used the SC1894 radio frequency power amplifier linearizer(RFPAL) provided by MAXIM Corp and through the look-up table technique confirmed the intermodulation distortion(IMD) performance and the adjusted channel leakage ratio(ACLR) improvement for bandwidth below 1 MHz which does not operate on existing chips. In the 400 MHz (400 ~ 500 MHz) band, IMD performance and the ACLR improvement of up to 17.46 dB based on 1-channel offset and up to 16.6 dB based on 2-channel offset were confirmed. In the system requiring the same linearity, we confirmed power efficiency improvement of 12.41% at output power of over 40 W.

• Journal of Advanced Navigation Technology
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• v.20 no.5
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• pp.490-495
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• 2016

In the present study, a microstrip-fed monopole antenna is proposed for wireless local area network (WLAN) operations which cover dual band of 2.4 GHz (2.4 ~ 2.484 GHz) and 5 GHz (5.15 ~ 5.825 GHz). In order to obtain its compact structure and good omnidirectional radiation patterns, a modified inverted L-shaped slot separated from ground for impedance matching in 5 GHz band is etched on 2.4 GHz printed monopole antenna. The proposed antenna is designed and fabricated on a FR4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of $30{\times}45mm^2$. The measured impedance bandwidths (${\mid}S_{11}{\mid}{\leq}-10dB$) of fabricated antenna are 270 MHz (2.22 ~ 2.48 GHz) in 2.4 GHz band and 890 MHz (5.08 ~ 5.97 GHz) in 5 GHz band respectively. In particular, high gain of more than about 4 dBi and good omnidirectional radiation patterns have been observed over the entire frequency band of interest.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1070-1076
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• 2007

In this paper, we study the characteristics of dual band microstrip antenna with the wedge-shaped radiation patch added the slot using air substrate. Wedge-shaped patch antenna with air substrate is avoided the large probe reactance associated with a thick substrate owing to the use of short probe and good impedance matching over a wide frequency range can be obtained. Slot on the antenna radiator varies the reactance component according to the employed frequency and affect the resonance freaqency of the antenna, therefore the antenna can resonate at the dual band(cellular and PCS band). The slot length and position have an effect on the bandwidth and input impedance of the antenna are optimized by simulation. From the experiment results for the fabricated antenna, -10 dB of $S_{11}$ is content with the allocated bandwidth of Cellular and PCS system and - 15 dB of cross polarization level. From the results of this paper, it has been confirmed that the proposed antenna can be used as the base station antenna fur Cellular and PCS band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.273-278
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• 2011

This paper has proposed a dual-band transmitter RF Front-end for IMT-Advanced systems which has been implemented in a 0.13-${\mu}m$ CMOS technology. The proposed dual-band transmitter RF Front-End covers 2300~2700 MHz, 3300~3800 MHz frequency ranges which support 802.11, Mobile WiMAX, and IMT-Advanced system. The proposed dual-band transmitter RF Front-End consumes 45 mA from a 1.2 V supply voltage. The performances of the transmitter RF Front-End are verified through post-layout simulations. The simulation results show a +0 dBm output power at 2 GHz band, and +1.3 dBm output power at 3 GHz band.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.145-155
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• 2023

A radial combiner with high efficiency characteristics in the X-band was designed and manufactured using a waveguide and matching structure. In particular, in order to manufacture it in a small size, a dual waveguide to coaxial transition structure was applied that allows two ports to be matched to one waveguide. Applying this structure makes it possible to manufacture smaller than typical coaxial to waveguide radial combiner. As a result of measurement in the X-band band of 9.2~10GHz, the return loss was less than -18.408dB and the output insertion loss was less than 0.206dB, and the output combining efficiency was obtained as high as 95.37% or more. It is expected that it can be used in the combining part for high output transmitters in the millimeter wave band in the future. In particular, the range of use is expected to increase by reducing the size and weight.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.4
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• pp.426-432
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• 2012

A fully-integrated low power K-band radar transceiver in 130 nm CMOS process is presented. It consists of a low-noise amplifier (LNA), a down-conversion mixer, a power amplifier (PA), and a frequency synthesizer with injection locked buffer for driving mixer and PA. The receiver front-end provides a conversion gain of 19 dB. The LNA achieves a power gain of 15 dB and noise figure of 5.4 dB, and the PA has an output power of 9 dBm. The phase noise of VCO is -90 dBc/Hz at 1-MHz offset. The total dc power dissipation of the transceiver is 142 mW and the size of the chip is only $1.2{\times}1.4mm^2$.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.5
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• pp.7-13
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• 1997

A X-band 3-stage monolithic LNA (low noise amplifier) with series feedback has been successfully desined and demonstrated by suign 0.5-$\mu\textrm{m}$ GaAs MESFET. In the design of the 3-stage LNA, the effects of series feedback to the noise figure, the gain, and the stability have been investigated ot find the optimal short stub length. As a result, the inductive series feedback topology which has 10degree short stub in the GaAs MESFET source lead, has been employed in the 1-st stage. The fabricated MMIC LNA's chip size is only 1mm$^{2}$/stage, which is smaller than the previously reported X-band MMIC input/output return losses are less than -10dB and -15dB, respectively. The noise figure (NF) is less than 2.6dB. The measured data show good agreement with the simulated values.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.6
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• pp.272-275
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• 2004

A balanced single side-band (SSB) mixer employing a sub-harmonic configuration is designed for up and down conversions in K-band. The designed mixer uses anti-parallel diode (APD) pairs to effectively eliminate even harmonics of the local oscillator (LO) spurious signal. To reduce the odd harmonics of LO at the RF port, we employ a balanced configuration for LO. The fabricated chip shows 12$\pm$2dB of conversion loss and image-rejection ratio of about 20dB for down conversion at RF frequencies of 24-27.5GHz. As an up-conversion mode, the designed chip shows 12dB of conversion loss and image-rejection ratio of 20 ～ 25 dB at RF frequencies of 25 to 27GHz. The odd harmonics of the LO are measured below -37dBc.