Analog Test and Measurement

Introduction

Analog test and measurement encompasses the techniques, equipment, and methodologies used to characterize, validate, and verify analog and mixed-signal electronic circuits. Unlike digital testing where signals are either high or low, analog measurements must accurately capture continuous quantities with their associated noise, distortion, and frequency-dependent behavior. This demands sophisticated instrumentation and deep understanding of measurement uncertainty.

From laboratory characterization that explores a design's full capabilities to high-volume production testing that must balance thoroughness with economics, analog test and measurement forms a critical bridge between design intent and manufacturing reality. Mastering these techniques ensures that electronic products meet their specifications while maintaining cost-effective production yields.

Articles

Analog Test Equipment and Techniques

Master specialized test instrumentation. Topics include mixed-signal ATE systems, source-measure units (SMUs), arbitrary waveform generators, digitizers and waveform capture, spectrum and network analyzers, time-domain reflectometry, jitter and phase noise measurement, and load-pull systems.

Built-In Self-Test for Analog

Embed test capabilities in analog circuits. This section addresses on-chip test signal generation, response analyzers, signature analysis, oscillation-based test, current monitoring techniques, process monitors, degradation detection, and self-calibration methods.

Characterization and Debugging

Diagnose and resolve analog circuit issues. Coverage encompasses probing techniques for high-impedance nodes, differential probing methods, current probing techniques, thermal imaging and analysis, noise source identification, EMI debugging, failure analysis techniques, and design validation procedures.

Production Test Strategies

Ensure manufactured devices meet specifications. Coverage includes wafer-level testing, final test methodologies, test time reduction techniques, multi-site testing, adaptive test methods, statistical post-processing, outlier detection, burn-in strategies, and reliability screening.

Key Concepts

Analog test and measurement builds upon several fundamental principles:

Measurement Uncertainty: Every measurement has associated uncertainty from instrument accuracy, environmental conditions, and measurement technique
Signal Integrity: Ensuring the measured signal accurately represents the device output without corruption from the measurement system
Traceability: Establishing an unbroken chain of calibration back to national standards
Repeatability and Reproducibility: Consistent results across multiple measurements, operators, and equipment
Test Coverage: Ensuring tests detect all relevant failure modes while minimizing test time

Testing Stages

Electronic products undergo testing at multiple stages throughout their lifecycle:

Design Verification: Confirming that prototypes meet design requirements under all specified conditions
Characterization: Fully exploring device performance to establish production test limits and application guidelines
Qualification: Demonstrating reliability through accelerated stress testing
Production Testing: Efficient verification that each manufactured unit meets specifications
Incoming Inspection: Verifying purchased components meet specifications
Failure Analysis: Investigating failed devices to determine root causes

Measurement Domains

Analog measurements span multiple domains, each requiring specialized techniques:

DC Measurements: Voltage, current, and resistance measurements at steady state
AC Measurements: Frequency response, gain, phase, and bandwidth characterization
Time Domain: Transient response, settling time, and timing measurements
Frequency Domain: Spectral analysis, distortion, and noise measurements
Statistical Analysis: Distribution analysis, process capability, and outlier detection