1,720,956 research outputs found
A Single-Chip K-Band CMOS FMCW Radar Transceiver
No full textThis paper presents a K-band FMCW radar transceiver IC, which is integrated in 0.13-μm CMOS technology. In the transmitter part, the class-C topology is adopted in the VCO block to achieve good phase noise performance. In the receiver part, the high gain of the LNA sufficiently suppresses the noise of the next stages to achieve a good noise figure in the receiver and the linearity of the receiver was improved by adoption of a gain control block, thereby achieving a wide dynamic range. As a result, a conversion gain of 35.7 dB, a P1dB of -12.7 dBm, and a DSB noise figure of 5.5 dB are achieved in the receiver part. The tuning range of 23.8~24.5 GHz and the phase noise of -103.1 dBc/Hz @ 1MHz offset are achieved in the transmitter part. The transceiver chip consumes 181.5 mW from a 1.5 V power supply. Using this chip, the K-band FMCW radar module is implemented and verified by measurement of the distance of an object
K-밴드 FMCW 레이더 CMOS 집적회로
No full text학위논문(박사) - 한국과학기술원 : 전기및전자공학부, 2015.8,[v, 64 p. :]This dissertation presents K-band FMCW radar transceiver CMOS ICs. Three improved FMCW radar systems are proposed and implemented using 0.13-m CMOS technology. First, to extend the detection range, CMOS front-end ICs with 13.3 dBm output power for a K-band FMCW radar are presented in chapter II. The transmitter consists of a voltage controlled oscillator, divider chain, power amplifier, and additional buffers. The receiver consists of a low-noise amplifier, IQ mixers, an IQ generator, and buffers. The leakage problem can be mitigated by adopting differential topology and ground shielding. As a result, the receiver achieves a conversion gain of 35.7 dB, a P1dB of -31.6 dBm, and a DSB noise figure of 5.5 dB. The transmitter achieves the tuning range of 23.8~24.5 GHz and the phase noise of -104 dBc/Hz @ 1MHz offset. The receiver and transmitter chips consume 121.5 mW and 373.5 mW from a 1.5 V power supply, respectively. Using these two chips, the K-band FMCW radar module is implemented and verified by measuring the distance of an object.
In chapter III, a fully integrated K-band CMOS transceiver IC is presented. This transceiver IC is capable of dual-mode FMCW and UWB radar operation, providing full road coverage. In the transmitter part, the transmit signal can be switched between linearly frequency-modulated signal and time-slotted pulse signal according to the selected mode. In cooperation with control signal generator, the dual-functional block is switched between the pulse former and differential amplifier in UWB and FMCW modes, respectively. In the proposed receiver, not only the gain but also the bandwidth of the overall receiver can be tailored by switching of the center frequencies of stages and without lowering the quality factor of each stage. Therefore, dual-mode radar operation can be achieved in the single-path transceiver. Dual-mode operation was verified by the implementation of a transceiver module with the chip. It showed performance comparable to that of previously reported tranceivers despite the fact that it operates in dual modes.
Chapter IV presents a CMOS transceiver IC for a single-antenna FMCW radar. Since Tx leakage is critical in CMOS technology, a comprehensive leakage cancelling technique is proposed. The suggested tech-nique is able to cancel all the leakages caused by antenna reflection, asymmetry of balanced structure, and lossy substrate without additional power or area. Even-order harmonic leakage from the power amplifier is also reduced by an even harmonic filter, which is implemented simply by removing the real ground at a sym-metrical point. Matching networks are simplified by using a modified coupler structure. A low-noise combining amplifier is used to make the combining circuit compact. As a result, the transceiver achieves output pow-er of -1.6 dBm, phase noise of -105.44 dBc/Hz at 1MHz offset, receiver gain of 15.3 dB, and a noise figure of 11.6 dB. Tx leakages are cancelled to have isolation between Tx and Rx of 47.3 dB. The chip consumes 74.1 mA from a 1.5 V power supply. The chip area including pads is 1.7 mm 0.9 mm. Using this chip, a K-band FMCW radar module with a single antenna is implemented and verified.한국과학기술원 :전기및전자공학부
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
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