Browsing by Author "Chung, S. -J."

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A Compact Triple-band Filtering Microstrip Patch Antenna with the Same Polarization Planes
(2013-01-01)
Lee, Y. -J.
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Chung, S. -J.
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傳播研究所
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Institute of Communication Studies
A novel compact filtering microstrip patch antenna with triple-band operation is presented for WLAN/TD-LTE wireless applications. The proposed design is composed of a patch with slot-loaded parasitic elements and a stepped-impedance resonator which shares the same apertured ground. Using full-wave simulator HFSS, the broadside coupling coefficient can be extracted to determine the dimension of the aperture. The antenna has similar broadside radiation patterns in both E- and H-planes in the three frequency bands. Meanwhile, the antenna provides good selectivity as well as the same polarization planes.
Design of the current driver for inducing radiating ground edge current in a printed circuit board
(2012-04-24)
Liu, T-I.
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Wang, Y-S.
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Chung, S. -J.
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電信工程研究所
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Institute of Communications Engineering
A new current driver is proposed to effectively excite ground edge current for radiation without additional space reserved for antenna design. Since the current driver functions as a feeding structure as opposed to a radiator, it can be designed as small as possible without deteriorating the antenna radiation properties. A circuit model of the miniaturised balun (balanced to unbalanced transformer) is introduced to explain the current-inducing mechanism and to provide some valuable physical insights into the characteristics of the current driver. The effect of a shielding metal box for the proximity circuitry near the current driver is also investigated. And it is shown that the nearby shielding box has minor effect on the performance of the driver, which demonstrates the feasibility of the current driver as an effective antenna structure in a compact wireless terminal. The current driver operating at 2.45 GHz is printed on an FR4 substrate of 0.4 mm and occupies only a small area of about 4 mm by 4 mm. The simulated and measured results come to a great agreement. Nearly omni-directional radiation patterns with a peak gain of about 1 dBi are obtained. Owing to the design flexibilities and the compactness, the current driver is feasible for wireless applications.
Low-power VCO with phase-noise improvement in 0.18 mu m CMOS technology
(2010-09-30)
Liang, C. -P.
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Huang, T. -J.
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Rao, P. -Z.
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Chung, S. -J.
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傳播研究所
A low-power 5.25 GHz voltage-controlled oscillator ( VCO) with phase-noise improvement is designed in a 0.18 mu m CMOS 1P6M process. Owing to the use of a larger value of parallel capacitor, an additional harmonic-suppressed capacitor, and an appropriate bulk bias voltage of transistor, a good figure of merit of - 190 dBc/Hz can be achieved without extra chip area and CMOS process steps. The fabricated VCO operates from 5.12 to 5.36 GHz with a core power consumption of 1.9 mW and active chip area of 0.15 mm(2). The measured phase noise at 1 MHz offset is about - 119 dBc/Hz.
Quadrature current-reused divide-by-3 semi-dynamic frequency divider with active balun
(2012-01-05)
Lin, C. -Y.
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Rao, P. -Z.
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Lin, Y. -K.
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Chung, S. -J.
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傳播研究所
A divide-by-3 semi-dynamic frequency divider (SDFD) with active balun is presented using the current-reused technique. The proposed SDFD is composed of a Gilbert cell mixer, one stage of static divider and an active balun. The LO switching stage of the Gilbert cell mixer is also the current source of the static frequency divider to construct the current-reused architecture. At the incident power of 0 dBm, this frequency divider operates at the maximum bandwidth of 1100 MHz from 21.5 to 22.6 GHz. The power consumption of the divider is 12 mW at a 1.5 V supply voltage.