| Technology Challenges Motivating Adaptive Techniques | p. 1 |
| Introduction | p. 1 |
| Motivation for Adaptive Techniques | p. 2 |
| Components of Power | p. 2 |
| Relation Between Frequency and Voltage | p. 2 |
| Control Loop Implementation | p. 4 |
| Practical Considerations | p. 4 |
| Impact of Temperature and Supply Voltage Variations | p. 7 |
| Technology Issues Relating to Performance-Enhancing Techniques | p. 9 |
| Threshold Voltage Variation | p. 9 |
| Random Dopant Fluctuations | p. 11 |
| Design in the Presence of Threshold Voltage Variation | p. 13 |
| Technology Issues Associated with Leakage Reduction Techniques | p. 14 |
| Practical Considerations | p. 15 |
| Sources of Leakage Current | p. 16 |
| Transistor Design for Low Leakage | p. 20 |
| Conclusion | p. 21 |
| References | p. 21 |
| Technological Boundaries of Voltage and Frequency Scaling for Power Performance Tuning | p. 25 |
| Adaptive Power Performance Tuning of ICs | p. 25 |
| AVS- and ABB-Scaling Operations | p. 28 |
| Frequency Scaling and Tuning | p. 31 |
| Power and Frequency Tuning | p. 33 |
| Leakage Power Control | p. 37 |
| Performance Compensation | p. 40 |
| Conclusion | p. 44 |
| References | p. 46 |
| Adaptive Circuit Technique for Managing Power Consumption | p. 49 |
| Introduction | p. 49 |
| Adaptive VDD Control | p. 50 |
| Dynamic Voltage Scaling | p. 50 |
| Frequency and Voltage Hopping | p. 51 |
| Adaptive VTH Control | p. 55 |
| Reverse Body Bias (VTCMOS) | p. 55 |
| Self-Adjusting Threshold Voltage (SAT) Scheme | p. 55 |
| Leakage Current Monitor | p. 56 |
| VTH Controllability | p. 57 |
| Device Perspective | p. 59 |
| Forward Body Bias | p. 60 |
| Control Method and Granularity | p. 61 |
| VTH Control Under Variations | p. 64 |
| VTH Control vs. VDD Control | p. 66 |
| Hardware and Software Cooperative Control | p. 68 |
| Cooperation Between Hardware and Application Software | p. 68 |
| Cooperation Between Hardware and Operating System | p. 70 |
| Conclusion | p. 71 |
| References | p. 71 |
| Dynamic Adaptation Using Body Bias, Supply Voltage, and Frequency | p. 75 |
| Introduction | p. 75 |
| Static Compensation with Body Bias and Supply Voltage | p. 76 |
| Adaptive Body Bias | p. 77 |
| Adaptive Supply Voltage | p. 82 |
| Dynamic Variation Compensation | p. 84 |
| Dynamic Body Bias | p. 84 |
| Dynamic Supply Voltage, Body Bias, and Frequency | p. 87 |
| Design Details | p. 87 |
| Measurement Results | p. 89 |
| Conclusion | p. 92 |
| References | p. 92 |
| Adaptive Supply Voltage Delivery for Ultra-Dynamic Voltage Scaled Systems | p. 95 |
| Logic Design for U-DVS Systems | p. 97 |
| Device Sizing | p. 98 |
| Timing Analysis | p. 100 |
| SRAM Design for Ultra Scalable Supply Voltages | p. 101 |
| Low-Voltage Bit-Cell Design | p. 104 |
| Periphery Design | p. 105 |
| Intelligent Power Delivery | p. 107 |
| Deriving VDD for Given Speed Requirement | p. 107 |
| DC-DC Converter Topologies for U-DVS | p. 109 |
| Linear Regulators | p. 109 |
| Inductor Based DC-DC Converter | p. 109 |
| Switched Capacitor Based DC-DC Converter | p. 110 |
| DC-DC Converter Design and Reference Voltage Selection for Highly Energy-Constrained Applications | p. 112 |
| Minimum Energy Tracking Loop | p. 113 |
| Conclusion | p. 119 |
| References | p. 120 |
| Dynamic Voltage Scaling with the XScale Embedded Microprocessor | p. 123 |
| The XScale Microprocessor | p. 123 |
| Chapter Overview | p. 124 |
| XScale Micro-Architecture Overview | p. 125 |
| Dynamic Voltage Scaling | p. 126 |
| The Performance Measurement Unit | p. 127 |
| Dynamic Voltage Scaling on the XScale Microprocessor | p. 129 |
| Running DVS | p. 130 |
| Impact of DVS on Memory Blocks | p. 134 |
| Guaranteeing SRAM Stability with DVS | p. 134 |
| PLL and Clock Generation Considerations | p. 138 |
| Clock Generation for DVS on the 180 nm 80200 XScale Microprocessor | p. 138 |
| Clock Generation 90 nm XScale Microprocessor | p. 139 |
| Conclusion | p. 142 |
| References | p. 142 |
| Sensors for Critical Path Monitoring | p. 145 |
| Variability and its Impact on Timing | p. 145 |
| What Is a Critical Path | p. 147 |
| Sources of Path Delay Variability | p. 148 |
| Process Variation | p. 149 |
| Environmental Variation | p. 149 |
| Timing Sensitivity of Path Delay | p. 151 |
| Critical Path Monitors | p. 158 |
| Synchronizer | p. 158 |
| Delay Path Configuration | p. 159 |
| Time-to-Digital Conversion | p. 163 |
| Sensitivity | p. 167 |
| Control and Calibration | p. 168 |
| Conclusion | p. 169 |
| Acknowledgements | p. 171 |
| References | p. 171 |
| Architectural Techniques for Adaptive Computing | p. 175 |
| Introduction | p. 175 |
| Spatial Reach | p. 177 |
| Temporal Rate of Change | p. 177 |
| "Always Correct" Techniques | p. 179 |
| Look-up Table-Based Approach | p. 179 |
| Canary Circuits-Based Approach | p. 180 |
| In situ Triple-Latch Monitor | p. 181 |
| Micro-architectural Techniques | p. 182 |
| Error Detection and Correction Approaches | p. 183 |
| Techniques for Communication and Signal Processing | p. 184 |
| Techniques for General-Purpose Computing | p. 186 |
| Introduction to Razor | p. 187 |
| Razor Error Detection and Recovery Scheme | p. 188 |
| Micro-architectural Recovery | p. 190 |
| Recovery Using Clock-Gating | p. 190 |
| Recovery Using Counter-Flow Pipelining | p. 191 |
| Short-Path Constraints | p. 192 |
| Circuit-Level Implementation Issues | p. 192 |
| Silicon Implementation and Evaluation of Razor | p. 195 |
| Measurement Results | p. 196 |
| Total Energy Savings with Razor | p. 197 |
| Razor Voltage Control Response | p. 199 |
| Ongoing Razor Research | p. 200 |
| Conclusion | p. 202 |
| References | p. 203 |
| Variability-Aware Frequency Scaling in Multi-Clock Processors | p. 207 |
| Introduction | p. 207 |
| Addressing Process Variability | p. 209 |
| Approach | p. 209 |
| Combinational Logic Variability Modeling | p. 212 |
| Array Structure Variability Modeling | p. 213 |
| Application to the Frequency Island Processor | p. 215 |
| Addressing Thermal Variability | p. 217 |
| Experimental Setup | p. 218 |
| Baseline Simulator | p. 218 |
| Frequency Island Simulator | p. 219 |
| Benchmarks Simulated | p. 219 |
| Results | p. 220 |
| Frequency Island Baseline | p. 220 |
| Frequency Island with Critical Path Information | p. 221 |
| Frequency Island with Thermally Aware Frequency Scaling | p. 222 |
| Frequency Island with Critical Path Information and Thermally Aware Frequency Scaling | p. 224 |
| Conclusion | p. 225 |
| Acknowledgements | p. 225 |
| References | p. 225 |
| Temporal Adaptation - Asynchronicity in Processor Design | p. 229 |
| Introduction | p. 229 |
| Asynchronous Design Styles | p. 230 |
| Asynchronous Adaptation to Workload | p. 232 |
| Data Dependent Timing | p. 234 |
| Architectural Variation in Asynchronous Systems | p. 237 |
| Adapting the Latch Style | p. 237 |
| Controlling the Pipeline Occupancy | p. 240 |
| Reconfiguring the Microarchitecture | p. 241 |
| Benefits of Asynchronous Design | p. 244 |
| Conclusion | p. 245 |
| References | p. 245 |
| Dynamic and Adaptive Techniques in SRAM Design | p. 249 |
| Introduction | p. 249 |
| Read and Write Margins | p. 250 |
| Voltage Optimization Techniques | p. 251 |
| Column Voltage Optimization | p. 252 |
| Row Voltage Optimization | p. 255 |
| Timing Control | p. 257 |
| Array Power Reduction | p. 259 |
| Sleep Types | p. 259 |
| Active Sleep | p. 260 |
| Passive Sleep | p. 261 |
| P Versus N Sleep | p. 263 |
| Entering and Exiting Sleep | p. 264 |
| Dynamic Cache Power Down | p. 266 |
| Data Bus Encoding | p. 266 |
| Reliability | p. 267 |
| Soft Errors | p. 267 |
| Hard Errors | p. 267 |
| Cache Line Disable | p. 268 |
| Cache Line Remap | p. 268 |
| Defect Correction | p. 268 |
| Conclusion | p. 269 |
| References | p. 270 |
| The Challenges of Testing Adaptive Designs | p. 273 |
| The Adaptive Features of the Itanium 2 9000 Series | p. 273 |
| Active De-skew | p. 273 |
| Cache Safe Technology | p. 277 |
| Foxton Technology | p. 278 |
| The Path to Production | p. 281 |
| Fundamentals of Testing with Automated Test Equipment (ATE) | p. 281 |
| Manufacturing Test | p. 281 |
| Class or Package Testing | p. 283 |
| System Testing | p. 285 |
| The Impact of Adaptive Techniques on Determinism and Repeatability | p. 286 |
| Validation of Active De-skew | p. 287 |
| Testing of Active De-skew | p. 290 |
| Testing of Power Measurement | p. 291 |
| Power Measurement Impacts on Other Testing | p. 294 |
| Test Limitations and Guard-Banding | p. 296 |
| Guard-Band Concerns of Adaptive Power Management | p. 297 |
| Conclusion | p. 300 |
| References | p. 300 |
| Index | p. 303 |
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