• ETRI Journal
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• v.27 no.5
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• pp.569-578
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• 2005

The purpose of this paper is to describe the implementation of monolithically matching circuits, interface circuits, and RF core circuits to the same substrate. We designed and fabricated on-chip 1 to 6 GHz up-conversion and 1 to 8 GHz down-conversion mixers using a 0.8 mm SiGe hetero-junction bipolar transistor (HBT) process technology. To fabricate a SiGe HBT, we used a reduced pressure chemical vapor deposition (RPCVD) system to grow a base epitaxial layer, and we adopted local oxidation of silicon (LOCOS) isolation to separate the device terminals. An up-conversion mixer was implemented on-chip using an intermediate frequency (IF) matching circuit, local oscillator (LO)/radio frequency (RF) wideband matching circuits, LO/IF input balun circuits, and an RF output balun circuit. The measured results of the fabricated up-conversion mixer show a positive power conversion gain from 1 to 6 GHz and a bandwidth of about 4.5 GHz. Also, the down-conversion mixer was implemented on-chip using LO/RF wideband matching circuits, LO/RF input balun circuits, and an IF output balun circuit. The measured results of the fabricated down-conversion mixer show a positive power conversion gain from 1 to 8 GHz and a bandwidth of about 4.5 GHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.5
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• pp.337-343
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• 2013

In this paper, IEEE 802.11 based WLAN(5.2/5.8GHz) wideband Weathercock-shaped microstrip patch antenna was designed and manufactured. The antenna has a size of $17.4{\times}17.4mm^2$ and utilized FR-4 board. The size was minimized for mobility, and Weathercock-shaped U-slot and short-pin was inserted to satisfy adequate bandwidth and double bandwidth resonance characteristics. In addition, the antenna incorporated single both-sided patch, and simulation design optimized the Weathercock-shaped, position of the U-slot and the short-pin, and the length of the patch for the measurement. The manufactured antenna achieved a bandwidth of 695MHz from 5.2~5.8GHz zone(Return loss<-10dB). Achieved a beam width of $81.13^{\circ}$ and $85.43^{\circ}$ for 3-dB beam width of H plane and E p;ane radiation pattern, there was 3.17~4.85dBi gain.

• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.175-180
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• 2006

A single sideband(SSB) modulator operating at 5.5 GHz was fabricated by polarization inversion techniques. The dimension of domain inversion in a $LiINbO_3$ Mach-Zehnder structure was precisely controlled so that the RF signal applied on two Mach-Zehnder arms gives rise to $90^{\circ}$ effective phase difference. The single sideband suppression was maximized by optimization of the polarization status of the optical input and by the DC bias value. The fabricated device showed the center frequency of 5.8 GHz and the maximum sideband suppression of 33dB, where the bandwidth of 15 dB sideband suppression ranged over a 2.5 GHz span. The optical phase delay could be regulated by the DC bias voltage, fur example, the enhanced optical modulation sideband was distinctively switched from the upper sideband to the lower sideband by changing the DC bias voltage from 1.9 V to -10.6 V.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.145-151
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• 2008

In this paper, a dual band microstrip antenna with similar radiation pattern for the satellite internet service is proposed. The proposed antenna has two Y-shaped slots on the microstrip patch that is fabricated on RO4003 substrate with a dielectric constant of 3.38 and a thickness of 0.508 mm, and operates in the 2 GHz and 5 GHz bands. The size of the antenna is $50\times47.5\times6.5\;mm^3$, and fed by coaxial cable. The measured bandwidths of the antenna are 2.398$\sim$2.507 GHz and 5.458$\sim$5.972 GHz for VSWR<2. The measured gains are 8.92 dBi and 7.74 dBi, respectively, for the lower and upper bands.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.10 s.101
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• pp.1020-1027
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• 2005

In this paper, economic miniature RF transmitter module for intelligent transportation system(ITS) is described. This module which consists of ASK modulator, frequency synthesizer, power amplifier is operating at 5.8 GHz frequency band and implemented by using LTCC process technique. Thus, ultra small size of 0.8 CC and improved electrical performances has been obtained. From the test results, transmitting characteristics of 10 dBm ouput power and -46 dBc interchannel interference with 1.024 Mbps ASK modulated have been shown. Frequency synthesizer as a transmitting signal source reveals very short locking time of 26 usec and outstanding phase noise of -115 dBc/Hz at 1 MHz offset from 5.8 GHz center frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.5
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• pp.397-400
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• 2018

This paper presents a miniaturized 65 nm CMOS 30~46 GHz wideband amplifier. To minimize the chip area, coupled inductors are used in the matching networks. The measurement shows that the fabricated amplifier exhibits 9.3 dB of peak gain, 16 GHz of 3 dB bandwidth, and 42 % fractional bandwidth. The measured input and output return losses were more than 10 dB at 35.8~46.0 GHz and 28.6~37.8 GHz, respectively. The chip consumes 42 mW at 1.2 V. The measured group delay variation is 19.1 ps within the 3 dB bandwidth and the chip size excluding the pads is $0.09mm^2$.

• Journal of electromagnetic engineering and science
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• v.16 no.1
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• pp.35-43
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• 2016

A compact ultra-wide band antenna with a quadruple band-notched characteristic is proposed. The proposed antenna consists of a slotted trapezoid patch radiator, an inverted U-shaped band stop filter, a pair of C-shaped band stop filters, and a rectangular ground plane. To realize the quadruple notch-band characteristic, a U-shaped slot, a complementary split ring resonator, an inverted U-shaped band stop filter, and two C-shaped band stop filters are utilized in this antenna. The antenna satisfies the -10 dB reflection coefficient bandwidth requirement in the frequency band of 2.88-12.67 GHz, with a band-rejection characteristic in the WiMAX (3.43-3.85 GHz), WLAN (5.26-6.01 GHz), X-band satellite communication (7.05-7.68 GHz), and ITU 8 GHz (8.08-8.87 GHz) signal bands. In addition, the proposed antenna has a compact volume of $30mm{\times}33.5mm{\times}0.8mm$ while maintaining omnidirectional patterns in the H-plane. The experimental and simulated results of the proposed antenna are shown to be in good agreement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.89-96
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• 2000

In this paper, the design theory of the corrugated polarizer using square waveguide is proposed. In order to analysis the characteristic of square waveguide discontinuity as well as achievement of the low VSWR, we apply the modified $TE^\chi_mn$ mode matching method and the corrugated exponential function to the polarizer design. The results show a broadband characteristic that phase shift angle is nearly appeared $90^{\circ}$ in the range of 11.7-15.8GHz. Especially, we could be designed the Ku-band dual polarizer for the satellite broadcasting transponder with 300MHz bandwidth. Its phase shift angle and maximum VSWR, axial ratio are $90^{\circ},\pm1^{\circ}$, 1.03, and 1.0001 in the range of 11.7-12.0GHz and 14.5-14.8GHz, respectively.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.233-240
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• 2019

In this paper, due to the development of 5G communication technology, an antenna capable of covering both LTE and 5G bands is currently needed. In addition, we designed and manufactured a single feed antenna for the integrated public network (LTE) and 5G frequency dual band cover to satisfy the frequency bandwidth of more than 10% in each band. The antenna designed by adopting the dipole of the basic dipole antenna in a planar structure is a form in which the radiating element is vertically extended at all of the 700 MHz antennas and folded into a 'ㄷ' shape. In addition, the radiating element of the 700MHz band serves as a reflector of the 3.5GHz band radiating element. As a result, the 700 MHz band -10 dB bandwidth 104 MHz(14.8%) and 3.5 GHz band -10 dB bandwidth 660 MHz(18.8%) were obtained and the radiation pattern characteristic resulted in gains of 8.46 dBi, beam width E-plane 55°, H-plane 81° and 3.5 GHz bands 6.14 dBi, beamwidth E-plane 79°, H-Plane 49°.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.214-219
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• 2011

This paper presents a multi-band low noise amplifier(LNA) with switching operation for 2.4, 3.5 and 5.2 GHz bands using CMOS 0.18 um technology. The proposed circuit uses switching transistors to achieve the input and output matching for multi-band. By using the switching transistors, we can adjust the transconductance, gate inductance and gatesource capacitance at input stage and total output capacitance at output stage. The proposed LNA exhibits gain of 14.2, 12 and 11 dB and noise figure(NF) of 3, 2.9 and 2.8 dB for 2.4, 3.5 and 5.2 GHz, respectively.