Browsing by Author "Chang, Po-Yang"

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A low phase noise design for ultrawideband frequency synthesizer
(2007-05-01)
Chang, Po-Yang
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Wu, Hui-I
;
Jou, Christina F.
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傳播研究所
;
Institute of Communication Studies
A low phase-noise frequency synthesizer design for ultrawideband is demonstrated in a 0.18-mu m CMOS process. It combines a low phase-noise voltage-controlled oscillator with two-stage dividers and a switched buffer multiplexer with low layout complexity. Because of the symmetrical independent architecture of this switch buffer design, it can reduce the additional phase noise created by the traditional multiplexer stage. Here, this low phase noise design in three LO bands (8448, 4224, and 2112 MHz) is demonstrated. The measurement shows that in these three LO band, this new structure can achieve phase noise of less than - 121 dBc/Hz at I MHz offset. The frequency tuning range is 10% while consuming only 52.2 mW from a 1.8-V supply. (c) 2007 Wiley Periodicals, Inc.
A Quadrature Voltage Controlled Oscillator with 9 Selective Bands for UWB Communication
(2007)
Chang, Po-Yang
;
Wu, Hui-I
;
Jou, Christina F.
;
電信工程研究所
;
Institute of Communications Engineering
A 9 bands quadrature voltage-controlled oscillator (QVCO) for UWB communciation operating from 2 to 10 GHz is presented. The architecture consists of a wideband quadrature voltage-controlled oscillator (QVCO), 2-stage dividers, switch buffer and only one quadrature single-sideband (SSB) mixer. Fabricated in 0.18-mu m CMOS technology, this work achieves QVCO's measured phase noise less than -98 dBc/Hz at 1 MHz offset, and the simulated output powers of twelve bands have better than 35 dB sideband rejection while consuming 58.7mW of the core circuit and 48.7mW of the buffer from a 1.8-V supply. The simulated switching time for hopping frequency is about 1ns.
New insight on optical and magnetic Fe3O4 nanoclusters promising for near infrared theranostic applications
(2015-01-01)
Huang, Chih-Chia
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Chang, Po-Yang
;
Liu, Chien-Liang
;
Xu, Jia-Pu
;
Wu, Shu-Pao
Extensive efforts have been devoted to the development of a new biophotonic system using near infrared (NIR) nano-agents for non-invasive cancer diagnosis and therapy. Here, we developed a simple synthesis reaction of ligands, hydrazine, and iron(II) chloride to fabricate Fe3O4 cluster-structured nanoparticles (CNPs) with interesting NIR photonics and high magnetization (M-s: 98.3 emu g(-1) and proton relaxivity r(2): 234.6 mM(-1) s(-1)). These Fe3O4 CNPs exhibited optical absorption and reflection over all wavelengths, showing a U-shape absorption band with a low absorbance at a range of 750-950 nm and a progressive evolution in the second near infrared region. Strengthening of the scattering effect by incubating Fe3O4 CNPs with HeLa cells was observed when optical contrast enhancement was performed in an optical coherence tomography (OCT) microscope system with a laser light source at 860 nm. Using a 1064 nm laser at a low power density (380 mW cm(-2)) to excite the Fe3O4 CNPs (375 ppm([Fe])) led to a rise in the water temperature from 25 degrees C to 58 degrees C within 10 min. Finally, we present the first example of magneto-motive OCT cellular imaging combined with enhanced photothermal therapy using Fe3O4 CNPs and applying a magnetic field, which is promising for preclinical and clinical trials in the future.