Class D Amplifiers
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ICC 2021 - IEEE International Conference on Communications
IEEE ICC is one of the two flagship IEEE conferences in the field of communications; Montreal is to host this conference in 2021. Each annual IEEE ICC conference typically attracts approximately 1,500-2,000 attendees, and will present over 1,000 research works over its duration. As well as being an opportunity to share pioneering research ideas and developments, the conference is also an excellent networking and publicity event, giving the opportunity for businesses and clients to link together, and presenting the scope for companies to publicize themselves and their products among the leaders of communications industries from all over the world.
Energy conversion and conditioning technologies, power electronics, adjustable speed drives and their applications, power electronics for smarter grid, energy efficiency,technologies for sustainable energy systems, converters and power supplies
APEC focuses on the practical and applied aspects of the power electronics business. Not just a power designer’s conference, APEC has something of interest for anyone involved in power electronics including:- Equipment OEMs that use power supplies and converters in their equipment- Designers of power supplies, dc-dc converters, motor drives, uninterruptable power supplies, inverters and any other power electronic circuits, equipments and systems- Manufacturers and suppliers of components and assemblies used in power electronics- Manufacturing, quality and test engineers involved with power electronics equipment- Marketing, sales and anyone involved in the business of power electronic- Compliance engineers testing and qualifying power electronics equipment or equipment that uses power electronics
ISSCC is the foremost global forum for solid-state circuits and systems-on-a-chip. The Conference offers 5 days of technical papers and educational events related to integrated circuits, including analog, digital, data converters, memory, RF, communications, imagers, medical and MEMS ICs.
2020 IEEE International Symposium on Circuits and Systems (ISCAS)
The International Symposium on Circuits and Systems (ISCAS) is the flagship conference of the IEEE Circuits and Systems (CAS) Society and the world’s premier networking and exchange forum for researchers in the highly active fields of theory, design and implementation of circuits and systems. ISCAS2020 focuses on the deployment of CASS knowledge towards Society Grand Challenges and highlights the strong foundation in methodology and the integration of multidisciplinary approaches which are the distinctive features of CAS contributions. The worldwide CAS community is exploiting such CASS knowledge to change the way in which devices and circuits are understood, optimized, and leveraged in a variety of systems and applications.
Contains articles on the applications and other relevant technology. Electronic applications include analog and digital circuits employing thin films and active devices such as Josephson junctions. Power applications include magnet design as well asmotors, generators, and power transmission
Part I will now contain regular papers focusing on all matters related to fundamental theory, applications, analog and digital signal processing. Part II will report on the latest significant results across all of these topic areas.
IEEE Communications Magazine was the number three most-cited journal in telecommunications and the number eighteen cited journal in electrical and electronics engineering in 2004, according to the annual Journal Citation Report (2004 edition) published by the Institute for Scientific Information. Read more at http://www.ieee.org/products/citations.html. This magazine covers all areas of communications such as lightwave telecommunications, high-speed data communications, personal communications ...
The design and manufacture of consumer electronics products, components, and related activities, particularly those used for entertainment, leisure, and educational purposes
Publishes original and significant contributions relating to the theory, design, performance and reliability of electron devices, including optoelectronics devices, nanoscale devices, solid-state devices, integrated electronic devices, energy sources, power devices, displays, sensors, electro-mechanical devices, quantum devices and electron tubes.
2014 IEEE 57th International Midwest Symposium on Circuits and Systems (MWSCAS), 2014
Class D amplifiers are ubiquitous as audio amplifiers due to their significantly higher power-efficiency compared to their linear counterparts (such as Class AB) due to the digital-like switching mode operation of the Class D output stage. However, one drawback of Class D amplifiers is the susceptibility to supply noise, qualified and quantified by Power Supply Rejection Ratio (PSRR) and Power ...
IEEE Transactions on Circuits and Systems II: Express Briefs, 2015
Although class D amplifiers (CDAs) are highly advantageous over their linear amplifier counterparts in terms of power efficiency, their power efficiency remains undesirably low at nominal operation conditions where the output power is ~26 dB lower than its peak output power (due to the large crest factor of the audio/speech signal and headroom for adjustment). This is particularly the case ...
IET Circuits, Devices & Systems, 2010
A new transient analysis simulator for digital class D amplifiers, which significantly reduces the simulation time (more than ten-fold), and which provides an accurate and robust audio performance analysis, is presented in this study. This simulator, called a hybrid simulator, is of special interest because it provides a better compromise between time and accuracy when compared with previous work. This ...
IEEE Transactions on Circuits and Systems II: Express Briefs, 2008
Although power-supply noise, qualified by power- supply rejection ratio (PSRR), has been recognized as a potential drawback of Class-D amplifiers (CDAs) compared to linear amplifiers, the mechanisms of PSRR for CDAs are not well established. It is also not well recognized that the power-supply noise can intermodulate with the input signal, manifesting into power-supply induced intermodulation distortion (PS-IMD), and that ...
APCCAS 2006 - 2006 IEEE Asia Pacific Conference on Circuits and Systems, 2006
The mechanisms for the power supply noise in open-loop single-ended output and H-bridge output PWM class D amplifiers are investigated. Using Fourier series analyses, expressions for power supply rejection ratio (PSRR) and inter- modulation distortion (IMD) are derived. These expressions show that the former OL-CDA topology features a worse PSRR but a better IMD than the latter topology. The derived ...
Design of Monolithic Silicon-Based Envelope-Tracking Power Amplifiers for Broadband Wireless Applications
Micro-Apps 2013: Class F Power Amplifier Design, Including System-to-Circuit-to-EM Simulation
IMS 2014: Broadband Continuous-mode Power Amplifiers
IEEE Green Energy Summit 2015, Panel 2: How reliable is reliable enough?
IMS 2012 Microapps - Optimizing the Design and Verification of 4G RF Power Amplifiers
CIRCUIT DESIGN USING FINFETS
A 32GHz 20dBm-PSAT Transformer-Based Doherty Power Amplifier for MultiGb/s 5G Applications in 28nm Bulk CMOS: RFIC Interactive Forum 2017
IMS 2011 Microapps - Power Amplifier Design Utilizing the NVNA and X-Parameters
IMS 2012 Special Sessions: The Evolution of Some Key Active and Passive Microwave Components - K. R. Varian
2015 IEEE Honors: IEEE Ernst Weber Managerial Leadership Award - Shang-yi Chiang
IMS 2012 Special Sessions: The Evolution of Some Key Active and Passive Microwave Components - E. C. Niehenke
Coordination of NFPA and IEEE Consensus Document Development
MicroApps: Combining Planar and 3D EM Simulators for RF System Board Analysis (AWR)
CASS Lecture by Dr. Chris Hull, "Millimeter-Wave Power Amplifiers in FinFET Technology"
Micro-Apps 2013: Designing an ETSI E-Band Circuit for a MM Wave Wireless System
IMS 2015: Allen Katz - The Evolution of Linearizers for High Power Amplifiers
Engineering Workforce of the 21st Century: ISTAS 2019 Keynote by Babak D. Beheshti
Envelope Tracking and Energy Recovery Concepts for RF Switch-mode Power Amplifiers
Intermodulation Distortion Mitigation in Microwave Amplifiers and Frequency Converters
Class D amplifiers are ubiquitous as audio amplifiers due to their significantly higher power-efficiency compared to their linear counterparts (such as Class AB) due to the digital-like switching mode operation of the Class D output stage. However, one drawback of Class D amplifiers is the susceptibility to supply noise, qualified and quantified by Power Supply Rejection Ratio (PSRR) and Power Supply Induced Intermodulation Distortion (PS-IMD). In this paper, PSRR and PS-IMD of Single-ended, 2-state bridge-tied load (BTL) and 3-state BTL Class D amplifiers based on various carrier generators are investigated and compared. We show that the design of the carrier generator is critical and should be designed according to the structure of the Class D amplifier - we show in this paper that the same Carrier Generator may result in a high >70dB PSRR in a 3-state BTL Class D amplifier but an unacceptable 1dB PSRR in a 2-state BTL Class D amplifier. The investigation and comparison provide Class D amplifier designers useful insight on design and optimization of PSRR and PS-IMD.
Although class D amplifiers (CDAs) are highly advantageous over their linear amplifier counterparts in terms of power efficiency, their power efficiency remains undesirably low at nominal operation conditions where the output power is ~26 dB lower than its peak output power (due to the large crest factor of the audio/speech signal and headroom for adjustment). This is particularly the case for power-critical micropower applications such as hearing instruments. At nominal conditions, we find that the overcurrent protection circuit (for the output stage) is unexpectedly the most power-dissipative block in micropower CDAs. In this brief, we propose a novel ultralow-power overcurrent protection circuit, which features 67% lower power dissipation compared to conventional overcurrent protection circuit without compromising the IC area. To further verify the advantages of the proposed overcurrent protection circuit, an ultralow-power bang-bang CDA is designed. We show that, by employing the proposed overcurrent protection circuit, the power efficiency of the bang-bang CDA is significantly improved from 10.5% to 23.7% for a 64-Ω load and from 1.8% to 4.7% for a 400-Ω load.
A new transient analysis simulator for digital class D amplifiers, which significantly reduces the simulation time (more than ten-fold), and which provides an accurate and robust audio performance analysis, is presented in this study. This simulator, called a hybrid simulator, is of special interest because it provides a better compromise between time and accuracy when compared with previous work. This simulator consists in keeping the most representative states of the transient simulation to process an optimal simulation. The results obtained by this new technique are compared with standard transient simulations (Eldo) and with experimental measurements. The circuit under test has been designed on 0.13 m CMOS technology and, an FPGA is used for digital modulator implementation.
Although power-supply noise, qualified by power- supply rejection ratio (PSRR), has been recognized as a potential drawback of Class-D amplifiers (CDAs) compared to linear amplifiers, the mechanisms of PSRR for CDAs are not well established. It is also not well recognized that the power-supply noise can intermodulate with the input signal, manifesting into power-supply induced intermodulation distortion (PS-IMD), and that the PS-IMD can be significantly larger than the output distortion component at supply noise frequency. Furthermore, techniques to improve PSRR and PS-IMD are largely unreported in literature. In this brief, by means of a linear model, the PSRR and PS-IMD of single-feedback and double-feedback CDAs are analyzed and analytical expressions derived. A simple method is proposed to improve PSRR and PS-IMD with very low hardware overheads, and the improvement is ~ 26 dB. Analytical expressions for PSRR and PS-IMD of the improved design are derived and the pertinent parameters thereof are investigated. The model and analyses provide practical insight to the mechanisms of PSRR and PS-IMD, and how various parameters may be varied to meet a given specification.
The mechanisms for the power supply noise in open-loop single-ended output and H-bridge output PWM class D amplifiers are investigated. Using Fourier series analyses, expressions for power supply rejection ratio (PSRR) and inter- modulation distortion (IMD) are derived. These expressions show that the former OL-CDA topology features a worse PSRR but a better IMD than the latter topology. The derived expressions provide insight to the design of class D amplifiers and the analysis herein can be extended to closed-loop class D amplifiers
Filterless Class D amplifiers are based on the tri-state modulation architecture. In this study, the authors show that it is possible to employ the conventional Class D amplifier (that requires an LC output filter) as a filterless amplifier (hence not requiring the LC filter) if certain circuit conditions are satisfied - specifically a sufficiently high carrier frequency and a loudspeaker with sufficient inductance. As the high-frequency (beyond the audio range) components of the tri-state modulation and of the conventional modulation are dissipated in the loudspeaker, the rating of the loudspeaker would need to accommodate not only the audio signal power but also the power, <i>P</i> <sub>sw</sub>, due to the attenuation of the high- frequency components. By means of double-Fourier series analysis, the authors derive expressions for <i>P</i> <sub>sw</sub> and for power-efficiency of filterless Class D amplifiers based on the tri-state modulation and on the conventional modulation. These derived expressions provide meaningful insight into the design and application of these amplifiers, including practical means to improve their power-efficiency and the associated implications thereof. To determine the dissipation of the high-frequency components in the loudspeaker, the authors extend the well established loudspeaker model in the audio range to a high-frequency model, and the required added power rating of the loudspeaker is determined. The authors show, somewhat serendipitously, that if certain conditions are satisfied, the power-efficiency of the tri-state and the conventional filterless amplifiers are nearly comparable. The analyses herein are verified by experimental measurements.
Open-Loop Pulse Width Modulation (PWM) Class D amplifiers are attractive for power critical applications including hearing aids due to their simple hardware and high power-efficiency. Nevertheless, a drawback of open-loop Class D amplifiers is their susceptibility to supply noise, quantified by power supply rejection ratio (PSRR) and power supply induced intermodulation distortion (PS-IMD). In this paper, PSRR and PS-IMD of a commonly-used carrier generation method are investigated and compared against other common carrier generation methods. The analyses are verified by means of HSPICE simulations. The analyses and comparisons provide designers useful insight to the design of power critical Class D amplifiers.
The paper investigates the parameters affecting THD and PSRR in a PWM class D amplifiers with feedback. From our mathematical analysis, the authors show that the THD and PSRR of a PWM class D Amplifiers with feedback can be improved by shaping the frequency response of the 2nd-order integrator. The paper also shows how the THD can be further improved by means of dual-loop feedback. Simulation shows that the THD of the single-loop and the dual-loop feedback class D amplifiers can be improved by as much as 3 times and 12 times respectively
Class-D amplifiers have become very popular for audio-frequency power amplifiers. Their efficiency makes them attractive for high power or battery operated applications. The disadvantages of class-D amplifiers are almost all related to the undesirable high frequency harmonics caused by the modulation process. Passive LC filters are typically used to reduce these high frequency distortions. Higher order types of these filters require many bulky and expensive inductors. In this paper, the effective order for the class-D output restoration filter is effectively increased by adding a feedforward network to reduce the unwanted high frequency harmonics in the amplifier's load. A class- AB current source in the feedforward path counteracts the high frequency carrier and its associated sidebands. Initially, an analytical solution is developed and then implemented with discrete component models in SPICE. A frequency domain analysis is presented for the feedforward compensation technique as well as optimization by parametric variation. SPICE simulations verify the performance of the system by demonstrating the reduction of total harmonic distortion
Class D amplifiers (CDAs) are increasingly ubiquitous as the audio power amplifier (loudspeaker driver) in audio devices due to their significantly higher power-efficiency compared to their linear counterparts. In this paper, a comprehensive review on the design of audio Class D amplifiers is provided, including a comparison of commonly used design architectures/modulation schemes. The key design parameters, including Total Harmonic Distortion, Power Supply Rejection Ratio, Intermodulation Distortion, are discussed and the design tradeoffs between these parameters delineated.
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