An Integrated Mid Power Class D Audio Amplifier With Parametric Design Methodology

This invaluable textbook covers the theory and circuit design techniques to implement CMOS (Complementary Metal-Oxide Semiconductor) class-D audio amplifiers integrated circuits. The first part of the book introduces the motivation and fundamentals of audio amplification. The loudspeaker's operation and main audio performance metrics explains the limitations in the amplification process. The second part of this book presents the operating principle and design procedure of the class-D amplifier main architectures to provide the performance tradeoffs. The circuit design procedures involved in each block of the class-D amplifier architecture are highlighted. The third part of this book discusses several important design examples introducing state-of-the-art architectures and circuit design techniques to improve the audio performance, power consumption, and efficiency of standard class-D audio amplifiers.

Preface; Introduction and general survey; History, architecture and negative feedback; The general principles of power amplifiers; The small signal stages; The Class-B output stage; The output stage II; Compensation, slew-rate, and stability; Power supplies and PSRR; Class-A power amplifiers; Class D power amplifiers; Class-G power amplifiers; FET output stages; Thermal compensation and thermal dynamics; Amplifier and loudspeaker protection; Grounding and practical matters; Testing and safety; Index.

This book is essential for audio power amplifier designers and engineers for one simple reason...it enables you as a professional to develop reliable, high-performance circuits. The Author Douglas Self covers the major issues of distortion and linearity, power supplies, overload, DC-protection and reactive loading. He also tackles unusual forms of compensation and distortion produced by capacitors and fuses. This completely updated fifth edition includes four NEW chapters including one on The XD Principle, invented by the author, and used by Cambridge Audio. Crosstalk, power amplifier input systems, and microcontrollers in amplifiers are also now discussed in this fifth edition, making this book a must-have for audio power amplifier professionals and audiophiles.

The consumer's demand for state-of-the-art multimedia devices such as smart phones and tablet computers has forced manufacturers to provide more system features to compete for a larger portion of the market share. The added features increase the power consumption and heat dissipation of integrated circuits, depleting the battery charge faster. Therefore, low-power high-efficiency circuits, such as the class-D audio amplifier, are needed to reduce heat dissipation and extend battery life in mobile devices. This dissertation focuses on new design techniques to create high performance class-D audio amplifiers that have low power consumption and occupy less space. The first part of this dissertation introduces the research motivation and fundamentals of audio amplification. The loudspeaker's operation and main audio performance metrics are examined to explain the limitations in the amplification process. Moreover, the operating principle and design procedure of the main class-D amplifier architectures are reviewed to provide the performance tradeoffs involved. The second part of this dissertation presents two new circuit designs to improve the audio performance, power consumption, and efficiency of standard class-D audio amplifiers. The first work proposes a feed-forward power-supply noise cancellation technique for single-ended class-D amplifier architectures to improve the power-supply rejection ratio across the entire audio frequency range. The design methodology, implementation, and tradeoffs of the proposed technique are clearly delineated to demonstrate its simplicity and effectiveness. The second work introduces a new class-D output stage design for piezoelectric speakers. The proposed design uses stacked-cascode thick-oxide CMOS transistors at the output stage that makes possible to handle high voltages in a low voltage standard CMOS technology. The design tradeoffs in efficiency, linearity, and electromagnetic interference are discussed. Finally, the open problems in audio amplification for mobile devices are discussed to delineate the possible future work to improve the performance of class-D amplifiers. For all the presented works, proof-of-concept prototypes are fabricated, and the measured results are used to verify the correct operation of the proposed solutions. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/154970

Integrated Audio Amplifiers in BCD Technology is the first book to describe the design at Audio Amplifiers using a Bipolar CMOS DMOS (BCD) process. It shows how the combination of the 3 processes, made available by advances in process technology, gives rise to the design of more robust and powerful audio amplifiers which can be more easily implemented in digital and mixed-signal circuits. Integrated Audio Amplifiers in BCD Technology starts with an introduction to audio amplifiers which includes a comparison of amplifier classes, general design considerations and a list of specifications for integrated audio power amplifiers. This is followed by an extensive discussion of the properties of DMOS transistors which are the key components in BCD technologies. Then the theory and the design of chargepump circuits is considered. In most BCD technologies only n-type DMOS transistors are available. Therefore a boosted supply voltage is required to achieve rail-to-rail output capability which can be generated with a chargepump. The new solutions that are found can also be used for many applications where DC-DC conversion with low output ripple is needed. Finally the design of audio power amplifier in BCD technology is discussed. The design concentrates on a new quiescent control circuit with very high ratio between quiescent current and maximum output current and on the output stage topologies. The problem of controlling the DMOS output transistors over a wide range of currents either saturated or non saturated requires a completely new design of the driving circuits that utilize of the special properties of the DMOS transistor. Integrated Audio Amplifiers in BCD Technology is essential reading for practising analog design engineers and researchers in the field. It is also suitable as a text for an advanced course on the subject. With a foreword by Ed van Tuijl.

Highly Linear Integrated Wideband Amplifiers: Design and Analysis Techniques for Frequencies from Audio to RF deals with the complicated issues involved in the design of high-linearity integrated wideband amplifiers for different operating frequencies. The book demonstrates these principles using a number of high-performance designs. New topologies for high linearity are presented, as well as a novel method for estimating the intermodulation distortion of a wideband signal. One of the most exciting results presented is an enhanced feedback configuration called feedback boosting that is capable of very low distortion. Also important is a statistical method for relating the intermodulation distortion of a wideband signal to the total harmonic distortion (THD) of a single tone. The THD, as opposed to the intermodulation distortion of the wideband signal, is easy to measure and use as a design parameter. Three different applications where high linearity is needed are identified, namely audio power amplifiers, wideband IF amplifiers and RF power amplifiers. For these applications high-performance integrated amplifier designs using novel topologies are presented together with measurement results. The audio amplifiers are built in CMOS and are capable of driving 8Omega loudspeaker loads directly without using any external components. One of the designs can operate on a supply voltage down to 1.5V. Both bipolar and CMOS wideband IF amplifiers are built; they are fully differential and have linearity from DC to 20 MHz. Finally, an RF power amplifier is built in CMOS, without using inductors, in order to investigate what performance can be achieved without them. Highly Linear Integrated Wideband Amplifiers: Design and Analysis Techniques for Frequencies from Audio to RF is an excellent reference for researchers and designers of integrated amplifiers, and may be used as a text for advanced courses on the topic.

This book introduces power amplifier design in 22nm FDSOI CMOS dedicated towards 5G applications at 28 GHz and presents 4 state-of-the-art power amplifier designs. The authors discuss power amplifier performance metrics, design trade-offs, and presents different power amplifier classes utilizing efficiency enhancement techniques at 28 GHz. The book presents the design process from theory, simulation, layout, and finally measurement results.

Audio amplifiers play an important role in every system that involves audible sound. General power amplifiers till recently have been very inefficient, bulky and unreliable. Though Class AB amplifiers have major market share in the audio industry because of their efficiency compared to previous classes of amplifiers such as Class A and Class B, recent demand for smaller devices with longer battery life has resulted in replacement of class AB amplifiers(linear amplifiers) with Class D(switching amplifiers). Class D amplifiers provide the balance between efficiency and distortion required by portable devices, hi-fi audio systems, as they utilize the switching operation where the transistors are either fully on or fully off resulting in amplification with zero power dissipation ideally. The main focus of this thesis is to analyze various design issues involved in implementation of class D amplifiers. As many designers in the future will be switching to Class D amplifiers because of the recent advances in switching amplifiers, an effort was made to develop the thesis so as to be able to serve as a basic reference guide which gives them a good understanding of existing architectures, challenges in efficient power amplifier design, modulation methods, power stage topologies and implementation of class D amplifiers. A detailed study of parameters and parasitics that affect the performance of class D amplifiers has been carried out with design, implementation, and simulation of various stages. Various component selection decisions and layout issues have been discussed for an efficient, EMI free, low distortion class D amplifier.

The modern wireless communication systems require modulated signals with wide modulation bandwidth. This, in turns, requires signals with very high dynamic range and peak-to-average power ratio (PAPR). This means that the amplifier in the base-station has to work at a power back-off as large as the dynamic range of the signal, so that the amplifier has a high linearity in this region. For the standard single-stage amplifiers, this large power back-off reduces the efficiency dramatically. In this work, a three-way Doherty power amplifier (DPA) aiming at high power efficiency within a dynamic range of 9.5 dB, is designed and fabricated using partitioning design approach. The partitioning design approach decomposes a complex design task into small-sized, well-controllable, and verifiable subcircuits. This advanced straight forward method has shown very promising results. Using this design approach, a three-way DPA has been designed to demonstrate the advantages of this reliable design technique as well. Based on the design of a single-stage power amplifier and proposing a novel output power combiner, a 6 W three-way DPA has been designed which allows the mandatory load modulation principle in three-way DPA structures to be realized with simpler elements, whereas the design of a standard Doherty combiner would have been very challenging and not practical due to the extremely small value of its characteristic line impedance. The proposed combiner is calculated for a three-way DPA with 2-mm AlGaN/GaN-HEMTs. The simulation result shows a very good load modulation for the amplifier, which confirms the theoretical expectation for a three-way DPA. The efficiency of the designed 6 W three-way DPA at large back-off shows very promising values compared to recently reported amplifiers. The measured IMD3 products confirm the good linearity of the amplifier as well. Accordingly, the proposed power combiner and the design strategy are recommended to be used as the preferred option for designing three-way DPA structures with very high output power.