Understanding ENOB (Effective Number of Bits) in Test and Measurement Equipment

Leading-edge electronic systems are becoming faster, denser, and more complex.

Leading-edge electronic systems are becoming faster, denser, and more complex. Engineers working on next-generation wireless, automotive radar, medical imaging, and high-speed computing are all pushing the boundaries of performance. As a result, testing these systems isn’t easy – signals are higher in frequency, denser in modulation, and more sensitive to errors. That makes the accuracy, precision and sensitivity of your test instruments more important than ever.

Most test and measurement instruments—from oscilloscopes to digitizers to spectrum analyzers—rely on analog-to-digital converters (ADCs) to capture real-world signals. These ADCs convert analog waveforms into the digital domain for measurement, analysis, and storage. However, there is a caveat: converting from analog to digital is never perfect. Every ADC introduces some level of error, and different errors add up in complex ways.

Instrument datasheets often run dozens of pages listing specifications for noise, distortion, linearity, jitter, resolution, and more. For engineers, who sometimes have varying experience levels in test engineering on its own, trying to translate all of these into a single understanding of “How good is this instrument?” can be overwhelming. That’s why the IEEE developed the concept of Effective Number of Bits (ENOB)—a single, powerful figure of merit that captures the real-world performance of a digitizer or oscilloscope. Read the full article on our website.