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A multi-band multi-standard RF front-end IEEE 802.16a for IEEE 802.16a and IEEE 802.11 a/b/g applications
No full textMulti-Band CMOS RF Front-End Circuit and Architecture Designs for BWA Systems
No full text支援多頻帶且多系統的收發機由於具有多樣化的功能，提高使用上的便利性，在現今的無線傳輸應用上越來越受到注目。一般而言，實現多頻帶收發器的方式即是使用多組的射頻模組，然而，這種方法增加了電路的複雜度，也提高晶片面積及成本。為了解決這個問題，本論文提出適用於都會型區域網路系統多頻帶射頻接收機的架構，利用電路共用的概念，在2.4 GHz，3.5 GHz及5.2 GHz三個頻帶中，使用一組射頻電路做頻帶切換。
在說明這個多頻帶射頻電路前，先介紹低雜訊放大器和混波器的設計考量，及「輪廓圖方法」的設計步驟。根據這個流程，設計且使用CMOS 0.18μm製程實現一個適用於IEEE 802.11a系統的低雜訊放大器。這個低雜訊放大器所占面積為0.6x1.29 mm2，並在1.8 伏特的供給電壓下，消耗功率為5.8毫瓦。
接下來介紹本論文所提出的多頻帶射頻前端電路架構，包括一個多頻帶低雜訊放大器，及雙降頻摺疊式混波器。此多頻帶低雜訊放大器採用切換多端點電感的方式達成頻帶的選擇。除了簡省面積外，切換電感可使各頻帶皆有較佳的Q值。此三頻帶低雜訊放大器以CMOS 0.18μm製程實現，面積為1.2x1.5 mm2，不考慮緩衝級下，操作頻率在2.4 GHz時消耗14.6毫瓦，在3.5 GHz和5.2 GHz時消耗24.9毫瓦。
整個接收機射頻前端電路以CMOS 0.18μm製程實現，所占面積1.28x1.76 mm2，在1.8伏特電壓下，總消耗功率在2.4 GHz為25.3毫瓦，3.5 GHz為51.2毫瓦，在5.2 GHz為39.2毫瓦。Multi-band and multi-standard transceivers attract more and more attention for their flexibility and functionality. Typically, the transceivers are realized by using two or more sets of RF blocks, which can handle the desired bands. However, this approach may increase chip area, the number of components, and the cost. A way to alleviate these problems is to use one set of RF block which can be tuned for multiple bands. In this thesis, a multi-band receiver architecture, operating at 2.4 GHz, 3.5 GHz and 5.2 GHz, is proposed for IEEE 802.16-2004 sub-11 GHz applications. The receiver RF front-end can achieve maximum hardware sharing while reducing chip area and cost.
Before going on the circuits of front-end, the design flows and considerations of RF blocks, i.e. LNA and mixer, are discussed. A technique called “Contour-plot methodology” has been published for LNA design, which can clearly provide designers the relations between design parameters and device size. The design flow of mixer is also presented using the contour-plot technique. Based on this methodology, a 5.2-GHz LNA with fully on-chip matching for WLAN systems is designed and implemented. Using a CMOS 0.18μm process, the LNA occupies an area of 0.6x1.29 mm2 and dissipates 5.8 mW from a 1.8 V power supply.
A tri-band LNA for the multi-band receiver RF front-end adopts a inductor-switching technique with a multi-tap inductor to select one of the three desired bands. Inductive switching is superior to capacitive switching since it can achieve better quality factors for each frequency band. Fabricated in CMOS 0.18μm technology, the tri-band LNA has an area of 1.2x1.5 mm2 and dissipates 14.6 mW in 2.4-GHz band and 24.9 mW in 3.5-GHz and 5.2-GHz band without buffer.
The proposed mixer uses a dual-conversion folded topology, which is composed of a single-balanced Gilbert-type mixer cascaded by two additional double-balanced PMOS switching pairs. System simulation shows that this topology can alleviate the noise and linearity requirements. The RF front-end occupies an area of 1.28x1.76 mm2 and dissipates 25.3 mW in 2.4 GHz, 51.2 mW in 3.5 GHz and 39.2 mW in 5.2 GHz, respectively.Chapter 1 Introduction 1
1.1 Motivations . . .. . . . . . . . . . . . . 1
1.2 IEEE 802.16 WMAN System Overview . . . . . .2
1.2.1 IEEE 802.16 Evolution . . . . . . . . . . 2
1.2.2 Applications . . . . . . .. . . . . . . . 3
1.2.3 Spectrum Picture . . . . . . . . . . . . 4
1.3 Thesis Overview . . . . . . . . . . . . . . 5
Chapter 2 System Requirements for WMAN 7
2.1 Introduction. . . . . . . . . . . . . . . . 7
2.2 Design Parameters for Wireless Receivers . .7
2.2.1 Noise Figure . . . . . . . . . . . . . . .8
2.2.2 Sensitivity . . . . . . . . . . . . . . . 8
2.2.3 Linearity . . . . . . . . . . . . . . . . 9
2.2.4 Dynamic Range . . . . . . . . . . . . . .13
2.3 IEEE 802.16 Receiver Specifications . . . .13
2.3.1 Signal-to-Noise Ratio (SNR) . . . . . . .13
2.3.2 Linearity . . . . . . . . . . . . . . . .13
2.3.3 Phase Noise . . . . . . . . . . . . . . .15
2.3.4 Image-Rejection Ratio (IRR) . . . . . . .16
2.3.5 Summary . . . . . . . . . . . . . . . . .17
Chapter 3 Receiver Architectures 19
3.1 Introduction . . . . . . . . . . . . . . . 19
3.2 Receiver Architectures . . . . . . . . . . 20
3.2.1 Heterodyne Receiver . . . . . . . . . . 20
3.2.2 Homodyne Receiver . . . . . . . . . . . 21
3.2.3 Low-IF Receiver . . . . . . . . . . . . 22
3.2.4 Dual-Conversion Receiver . . . . . . . . 22
3.2.5 Comparison of Receiver Architectures . . 24
3.3 Proposed Multi-Band Receiver Architecture .24
3.4 Building Circuit Block Specifications . . .26
Chapter 4 Low-Noise Amplifier 29
4.1 Introduction . . . . . . . . . . . . . . . 29
4.2 LNA Topology . . . . . . . . . . . . . . . 29
4.3 Noise in MOSFET . . . . . . . . . . . . . 32
4.3.1 Classical Channel Thermal Noise . . . . 32
4.3.2 Non-Quasi Static Gate Noise . . . . . . 33
4.4 Contour-Plot Methodology for LNA Design . 34
4.4.1 Design Procedure . . . . . . . . . . . . 35
4.4.2 Technology Parameter Fitting . . . . . . 35
4.4.3 Design Considerations . . . . . . . . . 38
4.4.4 Design Equations . . . . . . . . . . . . 44
4.4.5 Contour Plotting . . . . . . . . . . . . 45
4.5 A 5-GHz LNA for WLAN . . . . . . . . . . . 47
4.5.1 LNA Schematic . . . . . . . . . . . . . 48
4.5.2 Design Equations . . . . . . . . . . . . 48
4.5.3 Contour Plotting . . . . . . . . . . . . 50
4.5.4 Simulation Results . . . . . . . . . . . 51
4.6 Experimental Results . . . . . . . . . . . 53
4.6.1 Test Plan . . . . . . . . . . . . . . . 53
4.6.2 Measurement Results . . . . . . . . . . 54
4.6.3 Analysis of Inconsistency . . . . . . . 54
4.6.4 Layout Revision . . . . . . . . . . . . 56
Chapter 5 Multi-Band RF Front-End Design for WMAN 61
5.1 Introduction . . . . . . . . . . . . . . . . . . 61
5.2 Mixer Design . . . . . . . . . . . . . . . . . . 61
5.2.1 Mixer Topology . . . . . . . . . . . . . . . . 61
5.2.2 Mixer Fundamentals . . . . . . . . . . . . . . 63
5.2.3 Design Equations . . . . . . . . . . . . . . . 64
5.2.4 Contour-plot Methodology for Mixer Design . . . 66
5.3 RF Front-End Design for WMAN . . . . . . . . . . 69
5.3.1 Multi-band LNA . . . . . . . . . . . . . . . . 70
5.3.2 Dual-conversion Folded Mixer . . . . . . . . . 76
5.4 Simulation Results . . . . . . . . . . . . . . . 79
5.4.1 Multi-band LNA . . . . . . . . . . . . . . . . 79
5.4.2 Dual-conversion Folded Mixer . . . . . . . . . 80
5.4.3 RF Front-end . . . . . . . . . . . . . . . . . 80
5.5 Experimental Results . . . . . . . . . . . . . . 82
5.5.1 Multi-band LNA . . . . . . . . . . . . . . . . 82
Chapter 6 Conclusion 91
Bibliography 93
Appendix A 9
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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