1,720,987 research outputs found
Current mode elliptic filter design based on symmetrical current switching
No full textThis paper describes a current-mode elliptic filter structure based on dual OTAs and grounded capacitors. The filter is capable of producing both lowpass and highpass-notch responses without changing the filter structure. This is achieved using a symmetrical current switching technique based on two switches controlled with a 2-bit digital word. The proposed filter structure forms a basic 2nd-order building block in the design of high-order elliptic filters with tunable frequency response. To confirm the theoretical analysis, simulated and measured results of 4th-order elliptic lowpass and highpass filters with tunable bandwidth in the range of 0.65MHz to 1.3MHz are included. Finally, detailed analysis of the OTA non-ideal parameters on the filter performance is presented and an example is given
Current mode group delay equalisation using pole-zero mirroring techniques
No full textThis paper describes a new efficient method for designing current mode group delay equaliers. The method is based on introducing zeros into the right-hand s-plane by mirroring the poles of an LC ladder network. This is achieved by developing a current mode model capable of implementing the pole-zero mirroring technique. Using MO-OTA and grounded capacitors, the model is used to derive an nth-order active group-delay equaliser structure which is simpler, has better correction accuracy and is less sensitive when compared to cascaded based equaliers. The equaliser design involves two optimisation algorithms. Simulated and measured results demonstrate that the equaliser can effectively compensate the delay characteristics of a 7th-order 5.75MHz lowpass elliptic video filter to < 5ns ripple over 90% of the filter passband
CMOS equaliser for compensating sinc(x) distortion of video D/A converters
No full textThe authors describe the design and CMOS realisation of a new gm-C amplitude equaliser for correcting sinc(x) distortion in video D/A converters. Simulated and measured results demonstrate how the equaliser is used to correct distortion in D/A converters with Fs=13.5MHz to <0.08dB ripple over 5MHz bandwidth. Fabricated using 0.8µm CMOS process, the equaliser occupies 0.7mm2 and dissipates 20mW from a 5V supply
CMOS Design of Group Delay Equaliser
No full textTwo new current-mode allpass sections based on dual-output OTAs and triple-output OTAs and grounded capacitors are described. Techniques to minimise the equaliser active device count and efficiently simulate grounded resistors are proposed. A 5th-order group delay equaliser based on the presented allpass sections is designed and simulated using multiple-output CMOS OTAs. Numerical optimisation is used to determine the equaliser order and parameters. SPICE simulation results are given demonstrating that the equaliser can effectively compensate the delay characteristic of 4th-order 4MHz lowpass Chebyshev filter to <8ns ripple over 90% of the filter passband
Compensation of non-ideal effects in video frequency sinc(x) equalisers using tunable gm_c structure
No full textThe authors introduce a new biquadratic tunable-Gm_C amplitude equaliser structure for correcting sinc(x) distortion of video D/A converters. Unlike previously reported equalisers, the structure realises independent electronic control of W0 and Q by means of gm tuning, allowing simple compensation for active device non-ideal effects. A design example is given demonstrating the tunability and superior equaliser performance when compared with other structures. Simulation and measured results are included
Analysis and compensation of OTA non-ideal effects in video frequency CMOS sinc(x) equaliers
No full textThis paper presents a detailed analysis and minimisation of OTA non-ideal effects in sinc(x) amplitude equaliser operating at video frequencies. The compensation has been achieved by deriving a set of design equations incorporating the OTA input capacitance and output resistance and the polynomial coefficients used to correct the sinc(x) distortion. Simulated and measured results are included showing the effectiveness of the compensation technique
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
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