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Design of a Two Stage Low Noise System in the Frequency Band 1.8-2.2GHz for Wireless System
Zhao Xiaorong,Fan Honghui,Ye Feiyue,Qian Xiufang,Chen Dan,He Sheng 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.3
In first stage of each microwave receiver there is Low Noise Amplifier (LNA) circuit, and this stage has important rule in quality factor of the receiver. This paper presents the design of LNA and development of low bias (VD=3V, ID=20mA), the LNA operating in frequency range 1.8-2.2GHz using a feedback circuit. Design System (ADS) 2012 tool was used for design and simulation, and each design was tuned to get the optimum value for NF, power gain (S21), input return loss (S11) and reverse isolation (S12). Simulation results have indicated that the S21 achieves 33.2515±0.4475dB over the wide frequency band of 1.8-2.2 GHz, the gain was almost flat over the whole band. Noise figure (NF) maintains is 0.4945±0.0565 dB, S12 < -47.089 dB and S11 < -16.126 dB in the entire band.
Removal characteristics of Cd(II) ions from aqueous solution on ordered mesoporous carbon
Linhang Lu,Haibo Zhao,Lu Yan,Guowei Wang,Yulin Mao,Xin Wang,Kai Liu,Xiufang Liu,Qian Zhao,Tingshun Jiang 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.10
Ordered mesoporous carbon (CMK-3) was synthesized using SBA-15 mesoporous molecular sieve as a template and sucrose as carbon source. The materials were characterized by XRD, TEM and N2 physical adsorption technique. The resulting CMK-3 was used as adsorbent to remove Cd(II) ions from aqueous solution. The effect of pH, contact time and temperature on adsorption process was investigated in batch experiments. The results showed that the removal percentage could reach ca. 90% at the conditions of initial Cd(II) ions concentration of 20 mg/L, dose of 20mg, pH 6.5, contact time of 3h and 293K. Langmuir and Freundlich models were employed to describe the adsorption equilibrium. The kinetics data were described by the pseudo-first-order and pseudo-second-order models, respectively. The adsorption isotherm was well fitted to the Langmuir model, and the adsorption process was well described by the pseudo-second-order kinetic model.