An Introduction to Mixed-Signal IC Test and Measurement

Transcription

1 An Introduction to Mixed-Signal IC Test and Measurement Mark Burns Texas Instruments, Incorporated Gordon W. Roberts McGill University New York Oxford OXFORD UNIVERSITY PRESS 2001

2 PREFACE xvii Chapter 1: Overview of Mixed-Signal Testing 1.1 MIXED-SIGNAL CIRCUITS Analog, Digital, or Mixed-Signal? Common Types of Analog and Mixed-Signal Circuits Applications of Mixed-Signal Circuits WHY TEST MIXED-SIGNAL DEVICES? The CMOS Fabrication Process Real-World Circuits What Is a Test Engineer? POST-SILICON PRODUCTION FLOW Test and Packaging Characterization versus Production Testing TEST AND DIAGNOSTIC EQUIPMENT Automated Test Equipment Wafer Probers Handlers E-Beam Probers Focused Ion Beam Equipment Forced-Temperature Systems NEW PRODUCT DEVELOPMENT Concurrent Engineering MIXED-SIGNAL TESTING CHALLENGES Time to Market Accuracy, Repeatability, and Correlation Electromechanical Fixturing Challenges Economics of Production Testing 19 Chapter 2: The Test Specification Process 2.1 DEVICE DATA SHEETS Purpose of a Data Sheet Structure of a Data Sheet Electrical Characteristics GENERATING THE TEST PLAN To Plan or Not to Plan 31

3 vi Contents Structure of a Test Plan Design Specifications versus Production Test Specifications Converting the Data Sheet into a Test Plan COMPONENTS OF A TEST PROGRAM Test Program Structure Test Code and Digital Patterns Binning Test Sequence Control Waveform Calculations and Other Initializations Focused Calibrations and DIB Checkers Characterization Code Simulation Code "Debuggability" SUMMARY 43 Chapter 3: DC and Parametric Measurements 3.1 CONTINUITY Purpose of Continuity Testing Continuity Test Technique Serial versus Parallel Continuity Testing LEAKAGE CURRENTS Purpose of Leakage Testing Leakage Test Technique Serial versus Parallel Leakage Testing POWER SUPPLY CURRENTS Importance of Supply Current Tests Test Techniques DC REFERENCES AND REGULATORS Voltage Regulators Voltage References Trimmable References IMPEDANCE MEASUREMENTS Input Impedance Output Impedance Differential Impedance Measurements DC OFFSET MEASUREMENTS VMID and Analog Ground DC Transfer Characteristics (Gain and Offset) Output Offset Voltage (Fo) Single-Ended, Differential, and Common-Mode Offsets Input Offset Voltage (V O s) DC GAIN MEASUREMENTS Closed-Loop Gain Open-Loop Gain DC POWER SUPPLY REJECTION RATIO DC Power Supply Sensitivity DC Power Supply Rejection Ratio 72

4 vii 3.9 DC COMMON-MODE REJECTION RATIO CMRRofOpAmps CMRR of Differential Gain Stages COMPARATOR DC TESTS Input Offset Voltage Threshold Voltage Hysteresis VOLTAGE SEARCH TECHNIQUES Binary Searches versus Step Searches Linear Searches DC TESTS FOR DIGITAL CIRCUITS I m /IiL V IH IV IL VOHIVOL IOHIIOL' IOSH and IOSL Short Circuit Current SUMMARY 83 Chapter 4: Measurement Accuracy 4.1 TERMINOLOGY Accuracy and Precision Systematic Errors Random Errors Resolution (Quantization Error) Repeatability Stability Correlation Reproducibility CALIBRATIONS AND CHECKERS Traceability to Standards Hardware Calibration Software Calibration System Calibrations and Checkers Focused Instrument Calibrations Focused DIB Circuit Calibrations DIB Checkers Tester Specifications DEALING WITH MEASUREMENT ERROR Filtering Averaging Guardbanding BASIC DATA ANALYSIS Datalogs Histograms Noise, Test Time, and Yield SUMMARY 120

5 viii Contents Chapter 5: Tester Hardware 5.1 MIXED-SIGNAL TESTER OVERVIEW General-Purpose Testers versus Focused Bench Equipment Generic Tester Architecture DC RESOURCES General-Purpose Multimeters General-Purpose Voltage/Current Sources Precision Voltage References and User Supplies Calibration Source Relay Matrices Relay Control Lines DIGITAL SUBSYSTEM Digital Vectors Digital Signals Source Memory' Capture Memory Pin Card Electronics Timing and Formatting Electronics AC SOURCE AND MEASUREMENT AC Continuous Wave Source and AC Meter Arbitrary Waveform Generators Waveform Digitizers Clocking and Synchronization TIME MEASUREMENT SYSTEM Time Measurements Time Measurement Interconnects COMPUTING HARDWARE User Computer Tester Computer Array Processors and Distributed Digital Signal Processors Network Connectivity SUMMARY 144 Chapter 6: Sampling Theory 6.1 ANALOG MEASUREMENTS USING DSP Traditional versus DSP-Based Testing of AC Parameters SAMPLING AND RECONSTRUCTION Use of Sampling and Reconstruction in Mixed-Signal Testing Sampling: Continuous-Time and Discrete-Time Representation Reconstruction The Sampling Theorem and Aliasing Quantization Effects Sampling Jitter REPETITIVE SAMPLE SETS Finite and Infinite Sample Sets Coherent Signals and Noncoherent Signals 171

6 ix Peak-to-RMS Control in Coherent Multitones Spectral Bin Selection SYNCHRONIZATION OF SAMPLING SYSTEMS Simultaneous Testing of Multiple Sampling Systems ATE Clock Sources The Challenge of Synchronization SUMMARY 184 Chapter 7: DSP-Based Testing 7.1 ADVANTAGES OF DSP-BASED TESTING Reduced Test Time Separation of Signal Components Advanced Signal Manipulations DIGITAL SIGNAL PROCESSING DSP and Array Processing Fourier Analysis of Periodic Signals The Trigonometric Fourier Series The Discrete-Time Fourier Series Complete Frequency Spectrum Time and Frequency Denormalization Complex Form of the DTFS DISCRETE-TIME TRANSFORMS The Discrete Fourier Transform The Fast Fourier Transform Interpreting the FFT Output THE INVERSE FFT Equivalence of Time-and Frequency-Domain Information Parseval's Theorem Applications of the Inverse FFT Frequency-Domain Filtering Noise Weighting SUMMARY 240 APPENDIX A Chapter 8: Analog Channel Testing 8.1 OVERVIEW Types of Analog Channels Types of AC Parametric Tests Review of Logarithmic Operations GAIN AND LEVEL TESTS Absolute Voltage Levels Absolute Gain and Gain Error Gain Tracking Error PGA Gain Tests Frequency Response 265

7 8.3 PHASE TESTS Phase Response Group Delay and Group Delay Distortion DISTORTION TESTS Signal to Harmonic Distortion Intel-modulation Distortion SIGNAL REJECTION TESTS Common-Mode Rejection Ratio Power Supply Rejection and Power Supply Rejection Ratio Channel-to-Channel Crosstalk Clock and Data Feedthrough NOISE TESTS Noise Idle Channel Noise Signal to Noise, Signal to Noise and Distortion Spurious Free Dynamic Range Weighting Filters SIMULATION OF ANALOG CHANNEL TESTS MATLAB Model of an Analog Channel SUMMARY 308 Chapter 9: Sampled Channel Testing 9.1 OVERVIEW What Are Sampled Channels? Examples of Sampled Channels Types of Sampled Channels SAMPLING CONSIDERATIONS DUT Sampling Rate Constraints Digital Signal Source and Capture Simultaneous DAC and ADC Channel Testing Mismatched Fundamental Frequencies Undersampling Reconstruction Effects in AWGs, DACs, and Other Sampled-Data Circuits ENCODING AND DECODING Signal Creation and Analysis Data Formats Intrinsic Errors SAMPLED CHANNEL TESTS Similarity to Analog Channel Tests Absolute Level, Absolute Gain, Gain Error, and Gain Tracking Frequency Response Phase Response (Absolute Phase Shift) Group Delay and Group Delay Distortion Signal to Harmonic Distortion, Intennodulation Distortion Crosstalk CMRR 362

8 xi PSRandPSRR Signal-to-Noise Ratio and ENOB Idle Channel Noise SUMMARY 364 Chapter 10: Focused Calibrations 10.1 OVERVIEW Traceability to National Standards Why Are Focused Calibrations Needed? Types of Focused Calibrations Mechanics of Focused Calibration Program Structure DC CALIBRATIONS DC Offset Calibration DC Gain and Offset Calibrations Cascading DC Offset and Gain Calibrations AC AMPLITUDE CALIBRATIONS Calibrating AWGs and Digitizers Low-Level AWG and Digitizer Amplitude Calibrations Amplitude Calibrations for ADC and DAC Tests OTHER AC CALIBRATIONS Phase Shifts Digitizer and AWG Synchronization DAC and ADC Phase Shifts Distortion Tests Noise Tests ERROR CANCELLATION TECHNIQUES Avoiding Absolute Calibration Gain and Phase Matching Differential Gain and Differential Phase SUMMARY 400 Chapter 11: DAC Testing 11.1 BASICS OF CONVERTER TESTING Intrinsic Parameters versus Transmission Parameters Comparison of DACs and ADCs DAC Failure Mechanisms BASIC DC TESTS Code-Specific Parameters Full-Scale Range DC Gain, Gain Error, Offset, and Offset Error LSB Step Size DCPSS TRANSFER CURVE TESTS Absolute Error Monotonicity 412

9 xii Contents Differential Nonlinearity Integral Nonlinearity Partial Transfer Curves Major Carrier Testing Other Selected-Code Techniques DYNAMIC DAC TESTS Conversion Time (Settling Time) Overshoot and Undershoot Rise Time and Fall Time DAC-to-DAC Skew Glitch Energy (Glitch Impulse) Clock and Data Feedthrough DAC ARCHITECTURES 428 1L5.1 Resistive Divider DACs Binary-Weighted DACs PWMDACs Sigma-Delta DACs Companded DACs Hybrid DAC Architectures TESTS FOR COMMON DAC APPLICATIONS DC References Audio Reconstruction Data Modulation Video Signal Generators SUMMARY 437 APPENDIX A Chapter 12: ADC Testing 12.1 ADC TESTING VERSUS DAC TESTING Comparison of DACs and ADCs Statistical Behavior of ADCs ADC CODE EDGE MEASUREMENTS Edge Code Testing versus Center Code Testing Step Search and Binary Search Methods Servo Method Linear Ramp Histogram Method Conversion from Histograms to Code Edge Transfer Curves Accuracy Limitations of Histogram Testing Rising Ramps versus Falling Ramps Sinusoidal Histogram Method DC TESTS AND TRANSFER CURVE TESTS DC Gain and Offset MLandDNL Monotonicity and Missing Codes DYNAMIC ADC TESTS Conversion Time, Recovery Time, and Sampling Frequency Aperture Jitter Sparkling 472

10 xiii 12.5 ADC ARCHITECTURES Successive Approximation Architectures Integrating ADCs (Dual-Slope and Single-Slope) Flash ADCs Semiflash ADCs PDM (Sigma-Delta) ADCs TESTS FOR COMMON ADC APPLICATIONS DC Measurements Audio Digitization Data Transmission Video Digitization SUMMARY 480 Chapter 13: DIB Design 13.1 DIB BASICS Purpose of a Device Interface Board DIB Configurations Importance of Good DIB Design PRINTED CIRCUIT BOARDS Prototype DIBs versus PCB DIBs PCB CAD Tools Multilayer PCBs PCB Materials DIB TRACES, SHIELDS, AND GUARDS Trace Parasitics Trace Resistance Trace Inductance Trace Capacitance Shielding Driven Guards TRANSMISSION LINES Lumped-and Distributed-Element Models Transmission Line Termination Parasitic Lumped Elements GROUNDING AND POWER DISTRIBUTION Grounding Power Distribution Power and Ground Planes Ground Loops DIB COMPONENTS DUT Sockets and Contactor Assemblies Contact Pads, Pogo Pins, and Socket Pins Electromechanical Relays Socket Pins Resistors Capacitors Inductors and Ferrite Beads Transformers and Power Splitters 528

11 13.7 COMMON DIB CIRCUITS Local Relay Connections Relay Multiplexers Selectable Loads Analog Buffers (Voltage Followers) Instrumentation Amplifiers V M i D Reference Adder Current-to-Voltage and Voltage-to-Current Conversions Power Supply Ripple Circuits COMMON DIB MISTAKES Poor Power Supply and Ground Layout Crosstalk Transmission Line Discontinuities Resistive Drops in Circuit Traces Tester Instrument Parasitics Oscillations in Active Circuits Poor DIB Component Placement and PCB Layout SUMMARY 543 APPENDIX A Chapter 14: Design for Test (DfT) 14.1 OVERVIEW What Is DfT? Built-in Self-Test Differences between Digital DfT and Analog DfT Why Should We Use DfT? ADVANTAGES OF DfT Lower Cost of Test Increased Fault Coverage and Improved Process Control Diagnostics and Characterization Ease of Test Program Development System-Level Diagnostics Economics of DfT DIGITAL SCAN Scan Basics IEEE Std Standard Test Access Port and Boundary Scan Full Scan and Partial Scan DIGITAL BIST Pseudorandom BILBO Circuits Memory BIST Microcode BIST DIGITAL DfT FOR MIXED-SIGNAL CIRCUITS Partitioning Digital Resets and Presets Device-Driven Timing Lengthy Preambles MIXED-SIGNAL BOUNDARY SCAN AND BIST Mixed-Signal Boundary Scan (IEEE Std ) 569

12 xv Analog and Mixed-Signal BIST AD HOC MIXED-SIGNAL DfT Common Concepts Accessibility of Analog Signals Analog Test Buses, T-Switches, and Bypass Modes Separation of Analog and Digital Blocks Loopback Modes Precharging Circuits and AC Coupling Shorts On-Chip Sampling Circuits PLL Testability Circuits DAC and ADC Converters Oscillation BIST Physical Test Pads SUBTLE FORMS OF ANALOG DfT Robust Circuits Design Margin as DfT Avoiding Overspecification Predictability of Failure Mechanisms Conversion of Analog Functions to Digital Reduced Tester Performance Requirements Avoidance of Trim Requirements I DDQ Digital I DDQ Analog and Mixed-Signal I DDQ SUMMARY 589 APPENDIX A Chapter 15: Data Analysis 15.1 INTRODUCTION TO DATA ANALYSIS The Role of Data Analysis in Test and Product Engineering Visualizing Test Results DATA VISUALIZATION TOOLS Datalogs (Data Lists) Lot Summaries Wafer Maps Shmoo Plots Histograms STATISTICAL ANALYSIS Mean (Average) and Standard Deviation (Variance) Probabilites and Probability Density Functions The Standard Gaussian Cumulative Distribution Function <t>(z) Non-Gaussian Distributions Guardbanding and Gaussian Statistics Effects of Measurement Variability on Test Yield Effects of Reproducibilty and Process Variation on Yield STATISTICAL PROCESS CONTROL Goals of SPC Six-Sigma Quality 628

13 xvi Contents Process Capability, C p, and C pk Gauge Repeatability and Reproducibility Pareto Charts Scatter Plots Control Charts SUMMARY 634 Chapter 16: Test Economics 16.1 PROFITABILITY FACTORS What Is Meant by Test Economics? Time to Market Testing Costs Yield Enhancement DIRECT TESTING COSTS Cost Models Cost of Test versus Cost of Tester Throughput DEBUGGING SKILLS Sources of Error The Scientific Method Practical Debugging Skills Importance of Bench Instrumentation Test Program Structure Common Bugs and Techniques to Find Them EMERGING TRENDS Test Language Standards Test Simulation Noncoherent Sampling Built-in Self-Test Defect-Oriented Testing SUMMARY 659 ANSWERS TO SELECTED PROBLEMS 663 INDEX 677