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正A fully integrated multi-mode multi-band directed-conversion radio frequency(RF) receiver front-end for a TD-SCDMA/LTE/LTE-advanced is presented.The front-end employs direct-conversion design,and consists of two differential tunable low noise amplifiers(LNA),a quadrature mixer,and two intermediate frequency(IF) amplifiers.The two independent tunable LNAs are used to cover all the four frequency bands,achieving sufficient low noise and high gain performance with low power consumption.Switched capacitor arrays perform a resonant frequency point calibration for the LNAs.The two LNAs are combined at the driver stage of the mixer,which employs a folded double balanced Gilbert structure,and utilizes PMOS transistors as local oscillator(LO) switches to reduce flicker noise.The front-end has three gain modes to obtain a higher dynamic range.Frequency band selection and mode of configuration is realized by an on-chip serial peripheral interface(SPI) module.The frontend is fabricated in a TSMC 0.18-μm RF CMOS process and occupies an area of 1.3 mm~2.The measured doublesideband (DSB) noise figure is below 3.5 dB and the conversion gain is over 43 dB at all of the frequency bands. The total current consumption is 31 mA from a 1.8-V supply. 相似文献
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基于提高餐饮企业业务效率的目的,采用面向对象的设计方法(OOA),通过系统结构设计和前端开发,以A-DO.NET技术、C#语言和SQL后台数据库为基础。利用.NET的数据库访问技术ADO.NET技术实现程序与数据库之间的连接、打开和关闭等具体实验,得出了以.NET技术和C/S结构构建的小型餐饮消费管理系统具有运行稳定、成本低、安全可靠的功能。 相似文献
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Nam Quoc Ngo Rui Tao Zheng Ng J.H. Tjin S.C. Binh L.N. 《Lightwave Technology, Journal of》2007,25(3):799-802
A new hybrid optimization algorithm is proposed for the design of a fiber Bragg grating (FBG) with complex characteristics. The hybrid algorithm is a two-tier search that employs a global optimization algorithm (i.e., the staged continuous tabu search (SCTS) algorithm) and a local optimization method (i.e., the quasi-Newton method). First, the SCTS global optimization algorithm is used to find a "promising" FBG structure that has a spectral response as close as possible to the targeted spectral response. Then, a local optimization method, namely, the quasi- Newton method, is applied to further optimize the promising FBG structure obtained from the SCTS algorithm to arrive at a targeted spectral response. To demonstrate the effectiveness of the method, the design and fabrication of an optical bandpass filter are presented. 相似文献
168.
朱睿 《电信工程技术与标准化》2009,22(6):53-56
本文提出了一种基于无线传感器网络的应急通信系统的设计思路,可以有效的在恶劣条件下快速建立通信网络,为救援指挥及时提供所需的决策信息。阐述了系统的功能和组成,最后分析介绍了无线传感器网络的关键技术。 相似文献
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Due to the limited carrier concentration, 2D transition metal dichalcogenides have lower intrinsic dark current, and thus, are widely studied for high performance room photodetection. However, the light-matter interaction is still unclear, thus tuning the photoexcitation and further manipulating the photodetection is a challenge. Herein, large-area PtS films are synthesized, and the growth mechanism is investigated. It is demonstrated that PtS has an orthorhombic structure and exhibits the p-type semiconducting behavior. Then, MoS2/PtS p–n heterojunction is fabricated, and its energy diagram is discussed based on the Kelvin probe force microscopy. The contact potential difference is about 160 mV, which is much larger than previous 2D junctions facilitating the charge separation. Furthermore, the phototransistor based on MoS2/PtS p–n heterojunction is prepared, showing broadband photoresponse from visible to near-infrared. The manipulation of an external field on photoresponse, detectivity, and rise/fall time are explored and discussed. The responsivity can reach up to 25.43 A W−1, and the detectivity is 8.54 × 1012 Jones. These results indicate that PtS film is a prospective candidate for high-performance optoelectronic devices and broaden the scope of infrared detection materials. 相似文献