Browsing by Author "Liu, Szu-Ling"

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A 2.4 GHz CMOS Power Amplifier Using Asymmetric MOSFETs
(2012)
Liu, Szu-Ling
;
Huang, Yu-Chien
;
Chen, Ying-Jen
;
Chang, Tsu
;
Chin, Albert
In this paper, a two-stage 2.4 GHz power amplifier (PA) using the high-breakdown-voltage asymmetric NMOSFETs was implemented in a 0.18-mu m CMOS technology. In this process, the conventional NMOSFETs have a drain-to-source breakdown voltage (BVdss) about 3.5V, therefore restricting the available output power in PA designs. However, by using the special asymmetric NMOSFETs in the proposed PA, the circuit can safely operate at a supply voltage from 1.8 to 2.75V. Under a 2.75V operation, good power performances include a power gain of 20.4 dB, an output 1-dB compression point (P-out,P-1dB) of 21.5dBm and a power-added-efficiency (PAE) of 29.6%.
A Bias-Varied Low-Power K-band VCO in 90 nm CMOS Technology
(2012-06-01)
Liu, Szu-Ling
;
Tian, Xin-Cheng
;
Hao, Yue
;
Chin, Albert
;
電子工程學系及電子研究所
This letter presents a novel bias-varied low-power K-band voltage controlled oscillator (VCO) in a standard 90 nm CMOS technology. This circuit exhibits low power consumption of <= 3mW and a 12.2% tuning range with low phase noise characteristic. These performances are realized by combination of the transformer-feedback and the switchable active circuit block, which can control the dc power at different frequencies and improve the phase noise.
A Dual-Resonant Mode 10/22-GHz VCO With a Novel Inductive Switching Approach
(2012-07-01)
Liu, Szu-Ling
;
Chen, Kuan-Han
;
Chin, Albert
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents a novel dual-band voltage-controlled oscillator (VCO) in a standard 0.18-mu m CMOS technology. With special design in the LC tank, the circuit exhibits two oscillation modes in different frequency bands. The frequency band selection is achieved by a switched coupled inductor with the tunable inductance and quality factor. This VCO can operate in a 10-GHz band with 7.6% tuning range and a 22-GHz band with 8% tuning range, while the core circuit draws a dc current of 8.44 mA from a 1.8-V supply voltage. The figures-of-merit at 10- and 22-GHz bands are -184.63 and -181.81 dBc/Hz, respectively. These performances are comparable with state-of-the-art dual-band LC-VCOs.
A Low-Power K-Band CMOS VCO With Four-Coil Transformer Feedback
(2010-08-01)
Liu, Szu-Ling
;
Chen, Kuan-Han
;
Chang, Tsu
;
Chin, Albert
;
電子工程學系及電子研究所
A K-band low-power and low-phase-noise voltagec-ontrolled oscillator (VCO) is presented in this letter. By utilizing four-coil transformer feedback and forward body bias topology, good performances are obtained under a low-power supply with a 5.1% tuning range and a phase noise of -109.8 dBc/Hz at 1 MHz offset from the 21.37-GHz carrier frequency. The core circuit of this VCO only consumes 3.5 mW with a 0.6-V supply voltage and a 0.55-V body bias.
Design of a CMOS T/R Switch With High Power Capability: Using Asymmetric Transistors
(2012-12-01)
Liu, Szu-Ling
;
Wu, Meng-Hsiu
;
Chin, Albert
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A single-pole double-throw transmit/receive (T/R) switch has been realized by using both conventional and asymmetric MOSFETs in a standard 0.18 mu m CMOS technology. At 2.4 and 5.8 GHz, the asymmetric-transistor based T/R switch shows 2.7 dBm and 2.3 dBm improvements in measured 1 dB compression points (P(1 dB)s) than the conventional circuit of the same circuitry and layout, respectively. This switch also has good insertion losses of 0.62/0.7 and 0.94/1.2 dB for transmit-end/receive-end modes at 2.4 and 5.8 GHz, respectively.
Influence of acetic acid and ammonia catalyst on microstructure and properties of fluorinated polyimide-organosilicate hybrids
(2009-09-01)
Chiang, Tzu Hsuan
;
Liu, Szu-Ling
;
Lee, Shyh-Yang
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
This work investigates the preparation, microstructure and thermal/electrical properties of fluorinated polyimide-organosilicate hybrids utilizing acetic acid and ammonia as the catalysts for sol-gel process to grow organosilicate filler particles. Nano-scale organosilicate was observed in the base-catalyzed hybrids, which was ascribed to the relative inertness of base catalysts in promoting the hydrolysis reaction. This postponed the formation of particles and hence smaller particle size. Electrical measurements found that the base-catalyzed hybrids possess lower dielectric constants (kappa = 2.40 at nominal Si content = 0.4 mol) due to the absence of polar groups and formation of silica xerogels with high porosity in the samples. In both hybrids, leakage current densities increase with the increase of Si content. However, leakage current density of base-catalyzed hybrid was higher than that of acid-catalyzed hybrid at the same Si content due to the smaller particle size and highly porous feature of organosilicate embedded in the base-catalyzed hybrids. (C) 2009 Elsevier B.V. All rights reserved.
Investigation and Optimization of Low-Power Techniques in X-Band CMOS LC-VCO Design
(2011)
Tian, Xin-Cheng
;
Liu, Szu-Ling
;
Chen, Kuan-Han
;
Hao, Yue
;
電子工程學系及電子研究所
This paper investigates the optimization method for two low-power circuit techniques in low-power LC-VCO designs: Transformer feedback and forward body-bias. In addition to theoretical analysis, a low-power, low-voltage X-band VCO using these two techniques has also been implemented in a standard 0.18 mu m CMOS technology. This VCO exhibits good FOM and of -191.4dBc/Hz while the core circuit draws a DC current of 2.73mA from 0.55V low supply voltage. The excellent performance can be compared with the best reported X-band CMOS VCOs.
Preparation, microstructure, and property characterizations of fluorinated polyimide-organosilicate hybrids
(2008-11-01)
Chiang, Tzu Hsuan
;
Liu, Szu-Ling
;
Lee, Shyh-Yang
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
Synthesis of organosilicate (orgSiO(2)) via sol-gel process utilizing tetraethoxysilane (TEOS) and diethoxydimethylsilane (DEDMS) as precursors was carried out in this work. Various amounts of orgSiO(2) were blended with fluorinated poly(amic acid) (PAA) to form the PAA-orgSiO(2) precursors and the fluorinated polyimide (PI)-orgSiO(2) (i.e., the HR1) thin-film hybrids were prepared via spin coating and curing treatments. The PI-orgSiO(2)-AP (i.e., the HR2) hybrids were also prepared by using the PAA-orgSiO(2) precursors containing the amine silane coupling agent, the 3-aminopropyltriethoxysilane (APTEOS). The effects of APTEOS on promoting the crosslinking between organic and inorganic components as well as the network formation were investigated. Fourier-transform infrared spectroscopy (FTIR) showed that the orgSiO(2) particles indeed formed in the hybrids due to the emergence of absorption bands corresponding to Si-O-Si and O-Si-O bonds. Nuclear magnetic resonance (NMR) analyses revealed that the Q(4) units or, the four bridging bond units, dominate the structure of orgSiO(2). Thermal analysis indicated that the implantation of orgSiO(2) in PI matrix may effectively improve the thermal stability of hybrids. Transmission electron microscopy (TEM) revealed the formation of nano-scale orgSiO(2) particles in both hybrids and the sizes of orgSiO(2) are relating to the Si content. In HR1 hybrids, the particles obviously coarsened when Si content was high while, in HR2 hybrids, the addition of APTEOS effectively suppressed the phase separation and the ultrafine orgSiO(2) particles as small as 5 nm could be achieved in the sample with high Si content. Dielectric measurements showed that the lowest values of dielectric constants are 2.40 and 2.20 for HR1 hybrid at intermediate Si content = 0.4 mol and HR2 hybrid with the highest Si content = 0.8 mol, respectively. The suppression of dielectric constants was attributed to the absence of polar Si-OH and Si-H(2)O functional groups as well as the completion of hydrolysis in the hybrids. Formation of silica xerogels in the hybrids should be another cause of dielectric constant decrement, as indicated by the porosity calculation. Experimental results implied that the control of orgSiO(2) size to imply the closed-form silica structure is essential to the low-dielectric constant properties of hybrids. Leakage current density measurement illustrated that no deterioration effect occurs due to the addition of orgSiO(2) nanoparticles in polymeric matrix and satisfactory electrical properties are preserved for the hybrids for advanced low-dielectric applications. (C) 2008 Elsevier Ltd. All rights reserved.