Pulse Amplitude Modulation Transition Density Trigger in a Test and Measuring Device

The transition detection logic circuit in oscilloscopes addresses the limitations of conventional triggers by decoding PAM signals and ensuring equal representation of all transitions, improving signal integrity analysis in PAM systems.

DE102025130084A1Pending Publication Date: 2026-02-05TEKTRONIX INC
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Patent Information

Application Number
DE102025130084
Authority / Receiving Office
DE · DE
Patent Type
Applications
Current Assignee / Owner
Priority Date
2025-07-28
Filing Date
2025-07-30
Publication Date
2026-02-05

AI Technical Summary

Technical Problem

Conventional oscilloscope trigger systems struggle to provide a comprehensive visual representation of signal integrity for multi-stage pulse amplitude modulation (PAM) signals, as they often trigger on only one transition at a time, obscuring issues with other transitions and failing to display noise and jitter effectively.

Method used

Implementing a transition detection logic circuit that decodes PAM signals using clock and data recovery (CDR) techniques, combined with a round robin or random transition selection, and utilizing counters to ensure equal representation of all transitions, with configurable thresholds and peak tracking to trigger on significant transitions.

Benefits of technology

Enables a persistent display that overlays all transitions equally, providing a statistically significant analysis of signal integrity for PAM signals, enhancing the detection and visualization of signal quality in modern communication systems.

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Abstract

A test and measurement instrument comprises an input for receiving a pulse-amplitude modulated n-level signal (PAMn), an analog-to-digital converter (ADC) coupled to the input to digitize the PAMn signal, a capture memory coupled to the ADC and configured to store at least a portion of the digitized PAMn signal as a waveform, a trigger circuit coupled to the ADC and the capture memory to generate a trigger signal to cause the test and measurement instrument to initiate waveform acquisition, a PAMn clock and data recovery (CDR) circuit configured to decode bits from the PAMn signal, and a transition detection logic circuit coupled to the PAMn CDR circuit and the trigger circuit to detect symbol transitions based on the decoded bits and to initiate the trigger circuit.The trigger signal is designed to generate a response to the detection of a specific symbol transition.
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