http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Reduced Hybrid Ring Coupler Using Surface Micromachining Technology for 94-GHz MMIC Applications
Uhm, Won-Young,Beak, Tae-Jong,Ryu, Keun-Kwan,Kim, Sung-Chan The Korea Institute of Information and Commucation 2016 Journal of information and communication convergen Vol.14 No.4
In this study, we developed a reduced 94 GHz hybrid ring coupler on a GaAs substrate in order to demonstrate the possibility of the integration of various passive components and MMICs in the millimeter-wave range. To reduce the size of the hybrid ring coupler, we used multiple open stubs on the inside of the ring structure. The chip size of the reduced hybrid ring coupler with multiple open stubs was decreased by 62% compared with the area of the hybrid ring coupler without open stubs. Performance in terms of the loss, isolation, and phase difference characteristics exhibited no significant change after the use of the multiple open stubs on the inside of the ring structure. The reduced hybrid ring coupler showed excellent coupling loss of $3.87{\pm}0.33dB$ and transmission loss of $3.77{\pm}0.72dB$ in the measured frequency range of 90-100 GHz. The isolation and reflection were -48 dB and -32 dB at 94 GHz, respectively. The phase differences between two output ports were $180^{\circ}{\pm}1^{\circ}$ at 94 GHz.
Uhm, Won-Young,Ryu, Keun-Kwan,Kim, Sung-Chan The Korea Institute of Information and Commucation 2016 Journal of information and communication convergen Vol.14 No.1
In this paper, we develop a 94-GHz single balanced mixer with low conversion loss using planar Schottky diodes on a GaAs substrate. The GaAs Schottky diode has a nanoscale anode with a T-shaped disk that can yield high cutoff frequency characteristics. The fabricated Schottky diode with an anode diameter of 500 nm has a series resistance of 21 Ω, an ideality factor of 1.32, a junction capacitance of 8.03 fF, and a cutoff frequency of 944 GHz. Based on this technology, a 94-GHz single balanced mixer was constructed. The fabricated mixer shows an average conversion loss of -7.58 dB at an RF frequency of 92.5 GHz to 95 GHz and an IF frequency of 500 MHz with an LO power of 7 dBm. The RF-to-LO isolation characteristics were greater than -32 dB. These values are considered to be attributed to superior Schottky diode characteristics.
Development of Planar Schottky Diode on GaAs Substrate for Terahertz Applications
Uhm, Won-Young,Choi, Seok-Gyu,Han, Min,Ryu, Keun-Kwan,Kim, Sung-Chan The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.5
<P>In this paper, we demonstrate the planar Schottky diode on GaAs substrate for terahertz applications. A nanoscale dot and T-shaped disk has been developed as the anode for terahertz Schottky diode. The low parasitic elements of the nanoscale anode with T-shaped disk yield high cutoff frequency characteristic. The fabricated Schottky diode with anode diameter of 500 nm has series resistance of 21 Omega, ideality factor of 1.32, junction capacitance of 8.03 fF, and cutoff frequency of 944 GHz.</P>
High Conversion Gain Q-band Active Sub-harmonic Mixer Using GaAs PHEMT
Uhm, Won-Young,Lee, Bok-Hyung,Kim, Sung-Chan,Lee, Mun-Kyo,Sul, Woo-Suk,Yi, Sang-Yong,Kim, Yong-Hoh,Rhee, Jin-Koo The Institute of Electronics and Information Engin 2003 Journal of semiconductor technology and science Vol.3 No.2
In this paper, we have designed and fabricated high conversion gain Q-band active sub-harmonic mixers for a receiver of millimeter wave wireless communication systems. The fabricated active sub-harmonic mixer uses 2nd harmonic signals of a low local oscillator (LO) frequency. The fabricated mixer was successfully integrated by using $0.1{\;}\mu\textrm{m}$GaAs pseudomorphic high electron mobility transistors (PHEMTs) and coplanar waveguide (CPW) structures. From the measurement, it shows that maximum conversion gain of 4.8 dB has obtained at a RF frequency of 40 GHz for 10 dBm LO power of 17.5 GHz. Conversion gain from the fabricated sub-harmonic mixer is one of the best reported thus far. And a phase noise of the 2nd harmonic was obtained -90.23 dBc/Hz at 100 kHz offset. The active sub-harmonic mixer also ensure a high degree of isolations, which are -35.8 dB from LO-to-IF and -40.5 dB from LO-to-RF, respectively, at a LO frequency of 17.5 GHz.
( Won Hee Choi ),( Yong Sup Uhm ),( Young Jae Jeon ) 건국대학교 기초과학연구소 2002 理學論集 Vol.27 No.-
Liquid crystalline polymers(LCPs) have been used for the alignment of ferroelectric liquid crystal(FLC) molecules and the surface morphology of the LCP films have been observed by atomic force microscope. The uniform alignment of FLC molecules on the surface of the LCP films is observed without zig-zag defects. However, RN-715 polyimide alignment layer showed random alignment with some zig-zag defects in the surface stabilized ferroelectric liquid crystal(SSFLC) cells, The contrast ratio of the FLC cells are in the range of 12:l~20: 1 including two polarizers and they have a good memory capabilities.
Development of Planar Schottky Diode on GaAs Substrate for Terahertz Applications
Won-Young Uhm,Seok-Gyu Choi,Min Han,Keun-Kwan Ryu,Sung-Chan Kim 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.5
In this paper, we demonstrate the planar Schottky diode on GaAs substrate for terahertz applications. A nanoscale dot and T-shaped disk has been developed as the anode for terahertz Schottky diode. The low parasitic elements of the nanoscale anode with T-shaped disk yield high cutoff frequency characteristic. The fabricated Schottky diode with anode diameter of 500 nm has series resistance of 21 Ω, ideality factor of 1.32, junction capacitance of 8.03 fF, and cutoff frequency of 944 GHz.
A 94-GHz Phased Array Antenna Using a Log-Periodic Antenna on a GaAs Substrate
Uhm, Won-Young,Ryu, Keun-Kwan,Kim, Sung-Chan The Korea Institute of Information and Commucation 2015 Journal of information and communication convergen Vol.13 No.2
A 94-GHz phased array antenna using a log-periodic antenna has been developed on a GaAs substrate. The developed phased array antenna comprises four log-periodic antennas, a phase shifter, and a Wilkinson power divider. This antenna was fabricated using the standard microwave monolithic integrated circuit (MMIC) process including an air bridge for unipolar circuit implementations on the same GaAs substrate. The total chip size of the fabricated phased array antenna is 4.8 mm × 4.5 mm. Measurement results showed that the fabricated phased array antenna had a very wide band performance from 80 GHz to 110 GHz with return loss characteristics better than -10 dB. In the center frequency of 94 GHz, the fabricated phased array antenna showed a return loss of -16 dB and a gain of 4.43 dBi. The developed antenna is expected to be widely applied in many applications at W-band frequency.