1,720,958 research outputs found
E-Band Frequency Sextupler With >35 dB Harmonics Rejection Over 20 GHz Bandwidth in 55 nm BiCMOS
Full text linkA frequency multiplier by six (sextupler) for local oscillation (LO) generation in E-band is presented. It comprises a tripler, a doubler, and an output buffer. A detailed analysis is proposed to discuss the optimal order of the multiplication stages to minimize the unwanted harmonics of the input. Moreover, novel circuit topologies for the tripler and doubler are introduced. The tripler core is devised to reproduce the transcharacteristic of a third-order polynomial that ideally generates only the third harmonic of a sinusoidal input signal. By leveraging an envelope detector for adaptive biasing, the circuit maintains excellent suppression of the driving signal and unwanted harmonics over wide variations of the input power. The proposed topology improves output signal purity and current conversion efficiency against classical triplers based on the transistors biased in class C. The cascaded frequency doubler is based on a novel push-push configuration that provides a differential output and excellent odd-order harmonic rejection due to an enhanced robustness to amplitude and phase unbalances of the driving signal. The sextupler is fabricated in a 55-nm SiGe-BiCMOS technology. Driven with a 0-dBm input signal and consuming 63.1 mW of dc power, it delivers up to 5.6 dBm at 72 GHz. is above 0 dBm over 20-GHz bandwidth (BW), while undesired harmonics of the input are suppressed by more than 35 dB. Compared to previously reported millimeter-wave frequency multipliers, the sextupler demonstrates improved harmonic rejection, conversion gain, and efficiency, without compromising the operation BW and output power
High Gain 130GHz Frequency Doubler with Colpitts Output Buffer Delivering Pout up to 8dBm with 6% PAE in 55nm SiGe BiCMOS
No full textA mmWave frequency doubler in a SiGe BiCMOS technology is presented. The core of the circuit comprises a push-push pair, for second-harmonic generation, and a stacked common-collector Colpitts oscillator which works as a common-base injection-locked amplifier to boost the conversion gain and output power. The class-C operation of the transistor in the Colpitts buffer leads to a pulsed current shape with enhanced second-harmonic content. As a result, the power conversion gain of the frequency doubler is increased by up to 10dB, compared to the push-push pair alone. Moreover, the common-collector configuration keeps separate the oscillator tank from the load, allowing independent optimization of the harmonic conversion efficiency and the load impedance for maximum power delivery. Realized in a SiGe BiCMOS technology with 330GHz fmax, the proposed frequency doubler delivers Pout up to 8dBm at 130GHz with 13dB conversion gain and 6.3% Power Added Efficiency. A Figure of Merit is proposed to benchmark frequency doublers and the presented chip shows up to 3 times improvement compared to previously reported designs in the same frequency range
D-Band RX Front-End With a 0 –360 Phase Shifter Based on Programmable Passive Networks in SiGe-BiCMOS
No full textActive phased arrays are key enablers for high-capacity wireless links and imaging sensors at millimeter wave, but require advanced front-end circuits. On the receiver side, the front-end comprises a low-noise amplifier (LNA) followed by a programmable phase shifter (PS), required to adjust the phase of each channel before performing the coherent summation of the signals captured by different antenna elements. In D-band, conventional PSs based on the vector interpolation principle limit the dynamic range with a noise or linearity penalty due to transistors operating close to max, in currently available silicon technologies. This work presents a front-end where the variable phase shift is achieved using passive structures, with a noise figure equal to the insertion loss (IL) but inherently linear. Different passive networks providing a programmable phase shift in fine and coarse steps are developed and interleaved with active gain stages to build a 0 –360 PS. Cascode structures are used as gain stages, in the PS and in the preceding LNA, and reactive feedback is introduced around the common-emitter (CE) device to boost the gain. A D-band receiver front-end is implemented in BiCMOS 55-nm technology. With a power consumption of 80 mW from a 2 V supply, measurements prove 20 dB average gain, 130–170 GHz operating frequency with 0 –360 phase shift control, and average NF and of 7 dB and 2 dBm, respectively. Normalizing the dynamic range to power consumption, the achieved results compare favorably against state-of-the-art
40GHz Frequency Tripler with High Fundamental and Harmonics Rejection in 55nm SiGe-BiCMOS
No full textThis paper presents a novel frequency tripler circuit topology which yields a remarkable improvement on the suppression of the driving signal frequency at the output,compared to conventional designs exploiting transistors in class-C. The active core of the circuit approximates the transfer characteristic of a third-order polynomial that ideally produces only a third-harmonic of the input signal. Implemented in a 55nm SiGe-BiCMOS technology and consuming 13.6mA from 1.7V,the tripler demonstrates ~40dB suppression of the input signal and its 5th harmonic over 16% factional bandwidth and robustness to power variation of the driving signal over a 15dB range
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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