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SIMO DC-DC Converter for Automotive Audio Amplifier
Get PDFModern auto industry is ubiquitously deploying electronic systems for several applications like control, infotainment and security among others in the vehicles. Automotive infotainment is a key segment for the growth of automotive electronics as the vehicles, both light and heavy, require radio, video, navigation-assistance and telematics systems for both entertainment and networking.
Like any battery-operated systems, the automotive infotainment systems are required to provide high efficiency. One major constituent of in-vehicle infotainment being the radio, improving the overall efficiency of a car radio system is emphasized by the industry. In the state-of-the-art, the automotive audio amplifiers severely lack efficiency offering <40% in the mute condition. This research targets to improve the overall efficiency of an audio amplifier in a car radio by power supplying efficiently.
A Single Inductor Multiple Output dc-dc converter is explored as a supply voltage generator for an automotive audio amplifier in a car radio. The presence of line and load fluctuations, together with wide range of operating temperatures, in the automotive environment pose major challenge to the voltage regulation. A systematic feasibility study and analysis of specifications brought out the equivalence between the target SIMO converter and a non-inverting buck-boost SISO converter. Based on the equivalence, equilibrium and small signal models for the SIMO converter are developed. A voltage-mode, error-based controller is designed to control the dynamics of the converter. A novel power switching stage is conceived to generate the supplies required in a multi-channel class-D power amplifier. The switch
configuration is critical due the absence of a well-defined reference to one of the regulated outputs and the effect of package parasitics at high switching frequencies. The converter is charged synchronously and discharged quasi-synchronously to the loads. The switches are configured and driven optimally based on extensive simulations in the presence of package models to suppress the switching noise. In order to reduce the EM interference in the AM band of interest, the SIMO converter is switched at permissible high frequencies based on the EMI mask.
The automotive-class SIMO dc-dc converter is designed and integrated with a state-of-the-art class-D audio amplifier using 110nm BCD process technology offered by STMicroelectronics. The SIMO converter provides a battery tracking boost and a ground referred buck outputs for driving the class-D power stage. A unique feature of the converter is the generation of a floating voltage across half battery to supply the DSP core of the amplifier. The converter starts-up as boost converter alone followed entering boost-assisted SIMO converter mode. The active area occupied is 2.5mm2. The switching frequency is 2-2.4MHz. The converter has a load capability to drive up to 4 channels of a class-D power stage with peak efficiency of 86% and peak output power of 2.8W. The ripple voltage on the regulated outputs is below 25mV. The SIMO converter is able to sustain the automotive battery crank and dump conditions across the battery variation range of 4.5-27V. A line regulation of 6.3-16.2mV/V and a load regulation of 0.16mV/mA are provided by the SIMO converter. In the presence of wide range of battery variations, the SIMO converter incorporates all the necessary protections circuits and under/over voltage interrupts through I2C communication.Modern auto industry is ubiquitously deploying electronic systems for several applications like control, infotainment and security among others in the vehicles. Automotive infotainment is a key segment for the growth of automotive electronics as the vehicles, both light and heavy, require radio, video, navigation-assistance and telematics systems for both entertainment and networking.
Like any battery-operated systems, the automotive infotainment systems are required to provide high efficiency. One major constituent of in-vehicle infotainment being the radio, improving the overall efficiency of a car radio system is emphasized by the industry. In the state-of-the-art, the automotive audio amplifiers severely lack efficiency offering <40% in the mute condition. This research targets to improve the overall efficiency of an audio amplifier in a car radio by power supplying efficiently.
A Single Inductor Multiple Output dc-dc converter is explored as a supply voltage generator for an automotive audio amplifier in a car radio. The presence of line and load fluctuations, together with wide range of operating temperatures, in the automotive environment pose major challenge to the voltage regulation. A systematic feasibility study and analysis of specifications brought out the equivalence between the target SIMO converter and a non-inverting buck-boost SISO converter. Based on the equivalence, equilibrium and small signal models for the SIMO converter are developed. A voltage-mode, error-based controller is designed to control the dynamics of the converter. A novel power switching stage is conceived to generate the supplies required in a multi-channel class-D power amplifier. The switch
configuration is critical due the absence of a well-defined reference to one of the regulated outputs and the effect of package parasitics at high switching frequencies. The converter is charged synchronously and discharged quasi-synchronously to the loads. The switches are configured and driven optimally based on extensive simulations in the presence of package models to suppress the switching noise. In order to reduce the EM interference in the AM band of interest, the SIMO converter is switched at permissible high frequencies based on the EMI mask.
The automotive-class SIMO dc-dc converter is designed and integrated with a state-of-the-art class-D audio amplifier using 110nm BCD process technology offered by STMicroelectronics. The SIMO converter provides a battery tracking boost and a ground referred buck outputs for driving the class-D power stage. A unique feature of the converter is the generation of a floating voltage across half battery to supply the DSP core of the amplifier. The converter starts-up as boost converter alone followed entering boost-assisted SIMO converter mode. The active area occupied is 2.5mm2. The switching frequency is 2-2.4MHz. The converter has a load capability to drive up to 4 channels of a class-D power stage with peak efficiency of 86% and peak output power of 2.8W. The ripple voltage on the regulated outputs is below 25mV. The SIMO converter is able to sustain the automotive battery crank and dump conditions across the battery variation range of 4.5-27V. A line regulation of 6.3-16.2mV/V and a load regulation of 0.16mV/mA are provided by the SIMO converter. In the presence of wide range of battery variations, the SIMO converter incorporates all the necessary protections circuits and under/over voltage interrupts through I2C communication
An 86% efficiency SIMO DC-DC converter with one boost, one buck, and a floating output voltage for car-radio
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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
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