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Design of Phase Shifter for Microwave and Millimeter-wave Applications
No full text在本論文中實作了三個互補金氧半導體(CMOS)的相移器(phase shifter)，應用於直接升降頻(direct conversion)系統以及相位陣列(phase array)系統中。
第一個相移器是應用在60 GHz的直接升降頻系統中，由於直接升降頻通訊架構最大的問題是當I (in-phase) Q (quadrature phase)兩路訊號有誤差的時候，會導致傳輸時訊號品質下降，只要能夠降低IQ的誤差，就可以大幅提高訊號品質。因此，在這次的實作中，利用65 nm CMOS製程製作了一個30 GHz的連續可調式相移器。由於是應用在60 GHz的次諧波(sub-harmonic)混頻架構，所以本地振盪器(LO)只需用30 GHz，而在本地振盪器之後接上此相移器，將訊號分成IQ兩路分別到達IQ混頻器的輸入端。由於是次諧波的架構，相移器的輸出只需要相差45度就可以產生IQ兩路的訊號，而利用連續可調式相移器的好處，可以提供45±10度的相位差以及±2 dB的增益差，以改善IQ兩路的誤差。
第二與第三個相移器是應用在60 GHz的相位陣列系統中。由於相位陣列系統的空間多樣性與高陣列增益可以提高系統的頻譜使用效率，相位陣列系統已成為未來通訊系統的趨勢，而利用CMOS擁有高度整合的特點，可以將相位陣列系統應用於許多地方。
首先，第二個電路是一個切換式相移器，使用65 nm CMOS的製程實現。由於相移器在調整相位時損耗也會跟著改變，通常需要一個可調增益放大器(VGA)，然而當可調增益放大器調整增益時，相位又會跟著改變，導致相移器無法同時達到較低的增益誤差及相位誤差。在本設計中，提出了一種新型的可調增益放大器，藉由相位補償的機制，可以改善可調增益放大器在調整增益時相位產生誤差的效應，以達到較低的增益誤差及相位誤差。該相移器在60-66 GHz頻段中展示了小於7.2度的方均根(RMS)相位誤差及小於0.2 dB的方均根增益誤差。而在該頻段的平均的增益為-7 dB。
第三個電路是一個利用向量疊加法實現的相移器，使用90 nm CMOS製程實現。利用向量疊加法實現的相移器可合成任何相位及大小，因此可降低在單一頻率下的相位誤差。然而，一般向量疊加式相移器遇到的問題主要是頻寬會有所受限，因為不容易實現寬頻90度相位差的耦合器。而在本次的設計中，提出了一種能夠產生寬頻相位差的功率分配器，藉由此功率分配器可以提高相移器的頻寬。該相移器在57-66 GHz頻段中展示了小於5度的方均根(RMS)相位誤差，小於0.5 dB的方均根增益誤差，並且平均有-5 dB的增益。Three phase shifters in CMOS technology are implemented in this thesis. It can be used in a direct conversion system and phase array system.
The first phase shifter is applied in a 60 GHz sub-harmonic mixing direct conversion system. The LO frequency is set to be 30 GHz due to the sub-harmonic architecture. The most important problem in a direct conversion system is the IQ mismatch since the signal quality will be degraded by IQ mismatch. Reducing the IQ mismatch can increase the signal quality substantially. Therefore, a 30 GHz continuously tunable phase shifter using 65 nm CMOS technology is presented in this thesis. This phase shifter is set after the LO, dividing the LO signal into IQ paths and the IQ signals will be inserted to the IQ mixer, respectively. The IQ signals can be generated by a 45° phase shifter due to the sub-harmonic architecture. Using the continuously tunable phase shifter, this phase shifter can provide 45° ± 10° phase difference, and ±2 dB amplitude imbalance. Therefore, the IQ signals will have good match by using the phase shifter.
The second and the third phase shifters are applied in a 60 GHz phase array system. Phase array system has been widely used in nowadays communication system since the high spatial selectivity and the high array gain can improve the spectral efficiency. Since the CMOS technology have high integration, the phase array system can be applied in many respects.
The second circuit is a switching type phase shifter using 65 nm CMOS technology. Since the losses in different phase state are not the same, it will cause the amplitude error. To minimize the amplitude error of the STPS, a variable gain amplifier (VGA) can be cascaded with the phase shifter to compensate the different loss in each state.
However, when VGA provides different gain to compensate the different loss of each state, the insertion phase of the VGA will also be changed. Therefore, it is difficult to achieve low RMS phase error and low RMS gain error simultaneously. In this design, a STPS using a VGA with a new phase compensation technique is presented. The phase compensated VGA can provide variable gain without changing the insertion phase. Using the phase compensated VGA, the gain error of the STPS can be minimized without degrading the phase error. The measured RMS phase error and amplitude error are under 7.2° and 0.2 dB respectively in 60 to 66 GHz. The average amplitude is about -7 dB.
The third circuit is a vector sum phase shifter using 90 nm CMOS technology. The vector sum phase shifter can synthesize any amplitude and phase at certain frequency, so the phase error and amplitude error can be minimized. However, the vector sum phase shifter usually suffered from its narrow bandwidth since the IQ signals cannot be precise in wide frequency range. The proposed vector sum phase shifter using a wideband quadrature Wilkinson power divider to achieve low phase error in wideband. The measured RMS phase error and amplitude error are under 5° and 0.5 dB respectively in 57 to 66 GHz. The average amplitude is about -5 dB
Design of Microwave and Millimeter-wave Radar Systems for Imaging and Automotive Applications
No full text本論文的研究內容為微波與毫米波雷達系統，三個獨立的雷達系統分別應用於W頻段及K頻段被提出，包含雷達晶片及組裝模組。 在本論文中，一個操作於94-GHz高度整合的W頻段影像雷達被實現。利用相位陣列饋入技術達成電子掃瞄，準確測距技術則應用於距離偵測中。四個收發機作為影像感應器的前端電路，藉由相移器及功率合成器調整波束方向。內部31.3-GHz時脈訊號和三倍頻器提供了射頻載波及測距所需之計數時脈。應用覆晶技術將製作於低溫共燒陶瓷之天線與晶片組裝為一體積僅6.5 x 4.4 x 0.8立方公分之微小型模組。以台積65奈米製程制作，在1.2伏特的供應電壓下消耗960毫瓦之功率，晶片面積為3.6 x 2.1平方毫米。本原型達到+/-28度之掃瞄範圍，最遠2公尺之偵測距離及1毫米的距離解析度。 一個79-GHz高度整合的雙向脈波雷達系統應用注入再生接收機技術以65奈米CMOS製程實現。本系統應用新穎的阻抗轉換技術於功率放大器/低雜訊放大器中，比起傳統利用射頻切換器的架構，發射機效率及接收機雜訊指數皆有大幅度改善。本系統提出的注入再生振盪器也提高了接收機的增益及系統效率。量測之發射機輸出功率峰值及接收機轉換增益分別為9.2 dBm和42 dB。利用8 x 8平板天線配合板上匹配網路補償磅線效應，發射機之等效全向輻射功率為25 dBm，而E和H平面之波束寬度分別為11.5度和10度。測距範圍在0.3 ~ 1.5公尺間最大誤差量為7.2毫米。在1.2伏特的供應電壓，操作0.1%工作周期之脈波調變下共消耗107毫瓦之功率。 最後，一個高度整合之K頻段一發射機/四接收機脈波調變雷達系統以65奈米CMOS製程實現。利用8 x 8巴特勒矩陣波束合成器，在1公尺的距離下，本原型達成超過90度之雷達可視範圍及30度的角度解析度。可切換的功率放大器改善了平均載波洩漏功率及功率消耗。可程式化的脈波寬度、脈波重複時間，及針對鎖相迴路的溫度補償等技術使本雷達系統更加堅固。量測距離誤差在1.2公尺範圍內皆小於9.1毫米，在0.06%工作周期脈波調變操作下共消耗149毫瓦之功率。This dissertation presents the research on microwave and millimeter-wave radar systems. Three individual radar systems operating in W-band and K-band have been reported, including the chipsets and assembly modules. A fully-integrated W-band 3D image radar engine operated at 94 GHz utilizing phased-array-fed for electrical scanning and precise ranging technique for distance measurement has been realized. Four transmitters and four receivers form a sensor frontend with phase shifters and power combiners adjusting the beam direction. A built-in 31.3-GHz clock source and a frequency tripler provide both RF carrier and counting clocks for the distance measurement. Flipchip technique with low-temperature co-fired ceramic (LTCC) antenna design creates a miniature module as small as 6.5 x 4.4 x 0.8 cm^3. Designed and fabricated in 65-nm CMOS technology, the transceiver array chip dissipates 960 mW from a 1.2-V supply and occupies chip area of 3.6 x 2.1 mm^2. This prototype achieves +/-28° scanning range, 2-m maximum distance, and 1-mm depth resolution. A 79-GHz fully-integrated bidirectional pulse radar system with injection-regenerative receiver is demonstrated in 65 nm CMOS. The novel design for the impedance transformation of PA/LNA improves the TX efficiency and RX noise figure significantly in comparison with the traditional RF switch. The injection-regenerative oscillator is proposed to increase the receiver gain as well as the system efficiency. The measured TX peak Pout and RX conversion gain are 9.2 dBm and 42 dB, respectively. Using an 8 × 8 patch antenna array with on board matching network to compensate bonding wire effect, the TX EIRP is 25 dBm with the beamwidth of 11.5° and 10° in E and H plane, respectively. The distance measurement for 0.3 ~ 1.5 m with the maximum error of less than 7.2 mm. The overall dc consumption is only 107 mW from a single 1.2 V supply under pulse modulation with 0.1% duty cycle. Finally, a K-band fully-integrated 1TX/4RX pulse-modulated radar system fabricated in 65-nm CMOS technology is presented. Due to the 4 x 4 Butler matrix beamformer, this prototype achieves >90° radar field of view with 30° angular resolution at a distance of 1 m. The switchable PA improves the average carrier leakage power as well as the power consumption. The programmable pulse width, pulse repetition interval, and the temperature compensation technique in PLL, making the radar system more robust. The measured distance error is less than 9.1 mm inside the range of 1.2 m with the average power consumption of only 149 mW under pulse modulation with 0.06% duty cycle
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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