Designing Audio Power Amplifiers

<p>This comprehensive book on audio power amplifier design will appeal to members of the professional audio engineering community as well as the student and enthusiast. <em>Designing Audio Power Amplifiers</em> begins with power amplifier design basics that a novice can understand and moves all the way through to in-depth design techniques for very sophisticated audiophiles and professional audio power amplifiers. This book is the single best source of knowledge for anyone who wishes to design audio power amplifiers. It also provides a detailed introduction to nearly all aspects of analog circuit design, making it an effective educational text. </p><p>Develop and hone your audio amplifier design skills with in-depth coverage of these and other topics:</p><ul> <p> </p> <li>Basic and advanced audio power amplifier design</li> <p> </p> <li>Low-noise amplifier design</li> <p> </p> <li>Static and dynamic crossover distortion demystified</li> <p> </p> <li>Understanding negative feedback and the controversy surrounding it</li> <p> </p> <li>Advanced NFB compensation techniques, including TPC and TMC</li> <p> </p> <li>Sophisticated DC servo design</li> <p> </p> <li>MOSFET power amplifiers and error correction</li> <p> </p> <li>Audio measurements and instrumentation</li> <p> </p> <li>Overlooked sources of distortion</li> <p> </p> <li>SPICE simulation for audio amplifiers, including a tutorial on LTspice</li> <p> </p> <li>SPICE transistor modeling, including the VDMOS model for power MOSFETs</li> <p> </p> <li>Thermal design and the use of ThermalTrak™ transistors</li> <p> </p> <li>Four chapters on class D amplifiers, including measurement techniques</li> <p> </p> <li>Professional power amplifiers</li> <p> </p> <li>Switch-mode power supplies (SMPS).</li> </ul> <p> <b>Part 1: Audio Power Amplifier Basics</b></p><p>1. Introduction</p><p>1.1 Organization of the Book</p><p>1.2 The Role of the Power Amplifier</p><p>1.3 Basic Performance Specifications</p><p>1.4 Additional Performance Specifications</p><p>1.5 Output Voltage and Current</p><p>1.6 Basic Amplifier Topology</p><p>1.7 Summary</p><p>2. Power Amplifier Basics</p><p>2.1 BJT Transistors</p><p>2.2 JFETs</p><p>2.3 Power MOSFETs</p><p>2.4 Basic Amplifier Stages</p><p>2.5 Current Mirrors</p><p>2.6 Current Sources and Voltage References</p><p>2.7 Complementary Feedback Pair (CFP)</p><p>2.8 <i>Vbe</i> Multiplier</p><p>2.9 Operational Amplifiers</p><p>2.10 Amplifier Design Analysis</p><p>3. Power Amplifier Design Evolution</p><p>3.1 About Simulation</p><p>3.2 The Basic Power Amplifier</p><p>3.3 Adding Input Stage Degeneration</p><p>3.4 Adding a Darlington VAS</p><p>3.5 Input Stage Current Mirror Load</p><p>3.6 The Output Triple</p><p>3.7 Cascoded VAS</p><p>3.8 Paralleling Output Transistors</p><p>3.9 Higher Power Amplifiers</p><p>3.10 Crossover Distortion</p><p>3.11 Performance Summary</p><p>3.12 Completing an Amplifier</p><p>3.13 Summary</p><p>4. Building an Amplifier</p><p>4.1 The Basic Design </p><p>4.2 The Front-End: IPS, VAS and Pre-Drivers</p><p>4.3 Output Stage: Drivers and Outputs </p><p>4.4 Heat Sink and Thermal Management</p><p>4.5 Protection Circuits </p><p>4.6 Power Supply </p><p>4.7 Grounding </p><p>4.8 Building the Amplifier</p><p>4.9 Testing the Amplifier</p><p>4.10 Troubleshooting</p><p>4.11 Performance</p><p>4.12 Scaling</p><p>4.13 Upgrades</p><p>5. Noise</p><p>5.1. Signal-to-Noise Ratio</p><p>5.2. A-weighted Noise Specifications</p><p>5.3 Noise Power and Noise Voltage</p><p>5.4 Noise Bandwidth</p><p>5.5 Noise Voltage Density and Spectrum</p><p>5.6 Relating Input Noise Density to Signal-to-Noise Ratio</p><p>5.7 Amplifier Noise Sources</p><p>5.8 Thermal Noise</p><p>5.9 Shot Noise</p><p>5.10 Bipolar Transistor Noise</p><p>5.11 JFET Noise</p><p>5.12. Op Amp Noise</p><p>5.13 Noise Simulation</p><p>5.14 Amplifier Circuit Noise</p><p>5.15 Excess Resistor Noise</p><p>5.16 Zener and LED Noise</p><p>6. Negative Feedback Compensation and Slew Rate</p><p>6.1 How Negative Feedback Works</p><p>6.2 Input-referred Feedback Analysis</p><p>6.3 Feedback Compensation and Stability</p><p>6.4 Feedback Compensation Principles</p><p>6.5 Evaluating Loop Gain</p><p>6.6 Evaluating Stability</p><p>6.7 Compensation Loop Stability</p><p>6.8 Slew Rate</p><p>7. Amplifier Classes, Output Stages and Efficiency</p><p>7.1 Class A, AB and B Operation</p><p>7.2 The Complementary Emitter Follower Output Stage</p><p>7.3 Output Stage Efficiency</p><p>7.4 Complementary Feedback Pair Output Stages</p><p>7.5 Stacked Output Stages</p><p>7.6 Classes G and H</p><p>7.7 Class D</p><p>8. Summary of Amplifier Design Considerations</p><p>8.1 Power and Loads</p><p>8.2 Sizing the Power Supply</p><p>8.3 Sizing the Output Stage</p><p>8.4 Sizing the Heat Sink</p><p>8.5 Protecting the Amplifier and Loudspeaker</p><p>8.6 Power and Ground Distribution</p><p>8.7 Other Considerations</p><p>Part 2: Advanced Power Amplifier Design</p><p><b>9. Input and VAS Circuits</b></p><p>9.1 Single-Ended IPS-VAS</p><p>9.2 JFET Input Stages</p><p>9.3 Buffered Input Stages</p><p>9.4 CFP Input Stages</p><p>9.5 Complementary IPS and Push-Pull VAS</p><p>9.6 Unipolar Input Stage and Push-Pull VAS</p><p>9.7 Input Common Mode Distortion</p><p>9.8 Early Effect</p><p>9.9 Baker Clamps</p><p>9.10 Current Feedback Amplifiers</p><p>9.11 Example IPS/VAS</p><p>10. DC Servos</p><p>10.1 Origins and Consequences of DC Offset</p><p>10.2 DC Servo Basics</p><p>10.3 The Servo Is in the Signal Path</p><p>10.4 DC Offset Detection and Protection</p><p>10.5 DC Servo Example</p><p>10.6 Eliminating the Input Coupling Capacitor</p><p>10.7 DC Servo Design Issues and Nuances</p><p>11. Advanced Forms of Feedback Compensation</p><p>11.1 Understanding Stability Issues</p><p>11.2 Miller Compensation</p><p>11.3 Miller Input Compensation</p><p>11.4 Two-Pole Compensation</p><p>11.5 Transitional Miller Compensation</p><p>11.6 A Vertical MOSFET TMC Amplifier Example</p><p>11.7 Conclusion</p><p>12. Output Stage Design and Crossover Distortion</p><p>12.1 The Class AB Output Stage</p><p>12.2 Static Crossover Distortion</p><p>12.3 Optimum Bias and Bias Stability</p><p>12.4 Output Stage Driver Circuits</p><p>12.5 Output Transistor Matching Considerations</p><p>12.6 Dynamic Crossover Distortion</p><p>12.7 The Output Emitter Resistors</p><p>12.8 Output Networks</p><p>12.9 Output Stage Frequency Response and Stability </p><p>12.10 Sizing the Output Stage</p><p>12.11 Delivering High Current</p><p>12.12 Driving Paralleled Output Stages</p><p>12.13 Advanced Output Transistors</p><p>13. Output Stages II</p><p>13.1. VAS Output Impedance and Stability</p><p>13.2. Complementary Feedback Pair</p><p>13.3 Output Stages with Gain</p><p>13.4 Bryston Output Stage</p><p>13.5 ThermalTrak™ Output Stage</p><p>13.6 Class A Output Stage</p><p>13.7 Crossover Displacement (Class XD™)</p><p>13.8 Double Cross™ Output Stage</p><p>13.9 Sliding Bias and Non-switching Output Stages</p><p>13.10 LT1166 Output Stage</p><p>13.11 Measuring Output Stage Distortion</p><p>13.12 Setting the Bias</p><p>14. MOSFET Power Amplifiers</p><p>14.1 MOSFET Types and Characteristics</p><p>14.2 MOSFET Advantages and Disadvantages</p><p>14.3 Lateral vs. Vertical Power MOSFETs</p><p>14.4 Parasitic Oscillations</p><p>14.5 Biasing Power MOSFETs</p><p>14.6 Crossover Distortion</p><p>14.7 Driving Power MOSFETs</p><p>14.8 Paralleling and Matching MOSFETs</p><p>14.9 Simulating MOSFET Power Amplifiers</p><p>14.10 A Lateral MOSFET Power Amplifier Design</p><p>14.11 A Vertical MOSFET Power Amplifier Design</p><p>15. Error Correction</p><p>15.1 Feedforward Error Correction</p><p>15.2 Hawksford Error Correction</p><p>15.3 Error Correction for MOSFET Output Stages</p><p>15.4 Stability and Compensation</p><p>15.5 Performance and Design Issues</p><p>15.6 Circuit Refinements and Nuances</p><p>15.7 A MOSFET Power Amplifier with Error Correction</p><p>16. Other Sources of Distortion</p><p>16.1 Distortion Mechanisms</p><p>16.2 Early Effect Distortion</p><p>16.3 Junction Capacitance Distortion</p><p>16.4 Grounding Distortion</p><p>16.5 Power Rail Distortion</p><p>16.6 Input Common Mode Distortion </p><p>16.7 Resistor Distortion</p><p>16.8 Capacitor Distortion</p><p>16.9 Inductor and Magnetic Distortions</p><p>16.10 Magnetic Induction Distortion</p><p>16.11 Fuse, Relay and Connector Distortion</p><p>16.12 Load Induced Distortion</p><p>16.13 EMI-Induced Distortion</p><p>16.14 Thermally Induced Distortion (Memory Distortion)</p><p>Part 3: Real World Design Considerations</p><p>17. Output Stage Thermal Design and Stability</p><p>17.1 Power Dissipation vs. Power and Load</p><p>17.2 Thermal Design Concepts and Thermal Models</p><p>17.3 Transistor Power Ratings</p><p>17.4 Sizing the Heat Sink</p><p>17.5 The Bias Spreader and Temperature Compensation</p><p>17.6 Thermal Bias Stability</p><p>17.7 Thermal Lag Distortion</p><p>17.8 ThermalTrak™ Power Transistors</p><p>17.9 A ThermalTrak™ Power Amplifier</p><p>18. Safe Area and Short Circuit Protection</p><p>18.1 Power Transistor Safe Operating Area</p><p>18.2 Output Stage Safe Operating Area</p><p>18.3 Short Circuit Protection</p><p>18.4 Safe Area Limiting Circuits</p><p>18.5 Testing Safe Area Limiting Circuits</p><p>18.6 Protection Circuits for MOSFETs</p><p>18.7 Protecting the Driver Transistors</p><p>18.8 Loudspeaker Protection Circuits</p><p>19. Power Supplies and Grounding</p><p>19.1 The Design of the Power Supply</p><p>19.2 Sizing the Transformer</p><p>19.3 Sizing the Rectifier</p><p>19.4 Sizing the Reservoir Capacitors</p><p>19.5 Rectifier Speed</p><p>19.6 Regulation and Active Smoothing of the Supply</p><p>19.7 SPICE Simulation of Power Supplies</p><p>19.8 Soft-Start Circuits</p><p>19.9 Grounding Architectures</p><p>19.10 Radiated Magnetic Fields</p><p>19.11 Safety Circuits</p><p>19.12 DC on the Mains</p><p>19.13 Switching Power Supplies</p><p>20. Switching Power Supplies</p><p>20.1 Line DC Supply</p><p>20.2 Isolated DC-DC Converter</p><p>20.3 Buck Converters</p><p>20.4 Synchronous Buck Converter</p><p>20.5 Boost Converters</p><p>20.6 Buck-Boost Converters</p><p>20.7 Boost-Buck Converters</p><p>20.8 Cuk Converters</p><p>20.9 Forward Converters</p><p>20.10 Flyback Converters</p><p>20.11 Half-bridge Converters</p><p>20.12 Full-bridge Converters</p><p>20.13 Control ICs for PWM Converters</p><p>20.14 Resonant Converters</p><p>20.15 Quasi-Resonant Converters</p><p>20.16 EMI Filtering and Suppression</p><p>20.17 Power Factor Correction</p><p>20.18 Auxiliary Supplies</p><p>20.19 Switching Supplies for Power Amplifiers</p><p>20.20 Switching Supplies for Class D Amplifiers</p><p>21. Clipping Control and Civilized Amplifier Behavior</p><p>21.1 The Incidence of Clipping</p><p>21.2 Clipping and Sticking</p><p>21.3 Negative Feedback and Clipping</p><p>21.4 Baker Clamps</p><p>21.5 Soft Clipping</p><p>21.6 Current Limiting</p><p>21.7 Parasitic Oscillation Bursts</p><p>21.8 Selectable Output Impedance</p><p>22. Interfacing the Real World</p><p>22.1 The Amplifier-Loudspeaker Interface</p><p>22.2 EMI Ingress – Antennas Everywhere</p><p>22.3 Input Filtering</p><p>22.4 Input Ground Loops</p><p>22.5 Mains Filtering</p><p>22.6 EMI Egress</p><p>22.7 EMI Susceptibility Testing</p><p>Part 4: Simulation and Measurement</p><p>23. SPICE Simulation</p><p>23.1 Linear Technologies LTspice®</p><p>23.2 Schematic Capture </p><p>23.3 DC, AC and Transient Simulation </p><p>23.4 Distortion Analysis</p><p>23.5 Noise Analysis</p><p>23.6 Controlled Voltage and Current Sources</p><p>23.7 Swept and Stepped Simulations</p><p>23.8 Plotting Results</p><p>23.9 Subcircuits</p><p>23.10 SPICE Models</p><p>23.11 Simulating a Power Amplifier</p><p>23.12 Middlebrook and Tian Probes</p><p>24. SPICE Models and Libraries</p><p>24.1 Verifying SPICE Models </p><p>24.2 Tweaking SPICE Models </p><p>24.3 Creating a SPICE Model </p><p>24.4 JFET Models </p><p>24.5 Vertical Power MOSFET Models </p><p>24.6 LTspice VDMOS Models </p><p>24.7 The EKV Model </p><p>24.8 Lateral Power MOSFETs</p><p>24.9 Installing Models </p><p>25. Audio Instrumentation</p><p>25.1 Basic Audio Test Instruments</p><p>25.2 Dummy Loads</p><p>25.3 Simulated Loudspeaker Loads</p><p>25.4 THD Analyzer</p><p>25.5 PC-Based Instruments</p><p>25.6 Purpose-Built Test Gear</p><p>26. Distortion and its Measurement</p><p>26.1 Nonlinearity and its Consequences</p><p>26.2 Total Harmonic Distortion</p><p>26.3 SMPTE IM</p><p>26.4 CCIF IM</p><p>26.5 Transient Intermodulation Distortion (TIM) and SID</p><p>26.6 Phase Intermodulation Distortion (PIM)</p><p>26.7 Interface Intermodulation Distortion (IIM)</p><p>26.8 Multi-Tone Intermodulation Distortion (MIM)</p><p>26.9 Highly Sensitive Distortion Measurement</p><p>26.10 Input-Referred Distortion Analysis</p><p>27. Other Amplifier Tests</p><p>27.1 Measuring Damping Factor</p><p>27.2 Sniffing Parasitic Oscillations</p><p>27.3 EMI Ingress Susceptibility</p><p>27.4 Burst Power and Peak Current</p><p>27.5 PSRR Tests</p><p>27.6 Low-frequency Tests</p><p>27.7 Back-Feeding Tests</p><p>Part 5: Topics in Amplifier Design</p><p>28. The Negative Feedback Controversy</p><p>28.1 How Negative Feedback Got its Bad Rap</p><p>28.2 Negative Feedback and Open-loop Bandwidth</p><p>28.3 Spectral Growth Distortion</p><p>28.4 Global Versus Local Feedback</p><p>28.5 Timeliness of Correction</p><p>28.6 EMI from the Speaker Cable</p><p>28.7 Stability and Burst Oscillations</p><p>28.8 Clipping Behavior</p><p>29. Amplifiers without Negative Feedback</p><p>29.1 Design Tradeoffs and Challenges</p><p>29.2 Additional Design Techniques</p><p>29.3 An Example Design with No Feedback</p><p>29.4 A Feedback Amplifier with Wide Open-loop Bandwidth</p><p>30. Balanced and Bridged Amplifiers</p><p>30.1 Balanced Input Amplifiers</p><p>30.2 Bridged Amplifiers</p><p>30.3 Balanced Amplifiers</p><p>31. Integrated Circuit Power Amplifiers and Drivers</p><p>31.1 IC Power Amplifiers</p><p>31.2 The Gain Clones</p><p>31.3 The Super Gain Clone</p><p>31.4 Integrated Circuit Drivers</p><p>31.5 Summary</p><p>32. Professional Power Amplifiers</p><p>32.1 Environment and Special Needs</p><p>32.2 Output Stages and Output Power</p><p>32.3 Power Supplies</p><p>32.4 Cooling and Heat Removal</p><p>32.5 Microcomputers</p><p>32.6 Networked Control and Monitoring</p><p>32.7 Digital Signal Processing</p><p>32.8 DSP-Based Protection and Monitoring</p><p>32.9 The DSP to Class D Interface</p><p>32.10 Programming</p><p>32.11 Audio Networking</p><p>Part 6: Class D Audio Amplifiers</p><p>33. Class D Audio Amplifiers</p><p>33.1 How Class D Amplifiers Work</p><p>33.2 Class D Output Stages</p><p>33.3 Bridge Tied Load Designs</p><p>33.4 Negative Feedback</p><p>33.5 Noise Shaping in PWM Modulators with Feedback</p><p>33.6 Summary</p><p>34. Class D Design Issues</p><p>34.1 The Output Filter and EMI</p><p>34.2 Spread Spectrum Class D</p><p>34.3 Filterless Class D Amplifiers</p><p>34.4 Buck Converters and Class D Amplifiers</p><p>34.5 Sources of Distortion</p><p>34.6 Bus Pumping</p><p>34.7 Power Supply Rejection</p><p>34.8 Power Supplies for Class D Amplifiers</p><p>34.9 Damping Factor and Load Invariance</p><p>34.10 Summary</p><p>35. Alternative Class D Modulators</p><p>35.1 Self-Oscillating Loops</p><p>35.2 Sigma-Delta Modulators</p><p>35.3 Digital Modulators</p><p>36. Class D Measurement, Efficiency and Designs</p><p>36.1 Hybrid Class D</p><p>36.2 Measuring Class D Amplifiers</p><p>36.3 Achievable Performance</p><p>36.4 Integrated Circuits for Class D Amplifiers</p><p>36.5 Example Class D Amplifiers and Measurements</p>