Signal Evaluation
Superimposed waveform displays generated by capturing multi-bit sequence transitions evaluate signal margin and timing jitter on high speed digital channels. High frequency board characterization relies on eye diagram screening during post-fabrication signal integrity testing to verify driver, channel and receiver performance. This technique excludes static direct current voltage verification on slow control traces.
Distortion Analysis
Oscilloscopes sweep consecutive bit patterns over a single symbol period, overlaying logic zero to logic one and logic one to logic zero transitions. When attenuation, crosstalk or dispersion degrades the high speed signal, eye diagram screening shows vertical closure of the voltage amplitude and horizontal closure of the timing window. Signal integrity engineers measure eye height to evaluate noise margin and eye width to measure deterministic jitter across differential nets.
Imperfect termination or impedance mismatches create reflection ripples that corrupt the clear opening within the center of the display frame. Equalization adjustments on transmitter pre-emphasis alter waveform transition edges to maximize the open area of the eye mask. Thermal variations during operation shift trace resistance, altering eye height during environmental stress testing.
Compliance Standard
Physical layer standards define minimum acceptable eye opening masks for high speed protocol compliance. Defective solder joints or excessive micro-via stubs close eye masks, signaling potential transmission errors. Compliance screening ensures reliable data recovery at target bit rates.
