Receiver Sampling Circuit Margining for IC Signal Characterization
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Solution Overview
Problem
Characterizing and testing data communications links in high-frequency integrated circuits is challenging due to difficulties in measuring signal characteristics at the integrated circuit pad, which limits the quantification of operating margins and provides insufficient information about electrical parameters, such as time margin at the receiver.
Innovation Solution
A method and apparatus that determine voltage and timing margins by periodically sampling signals with a receiver sampling circuit, incrementally varying signal parameters, and adjusting phase alignment of sample clock signals to generate sampled versions of signals, allowing for margin value determination based on sampled data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If system level characterization is performed at pins of integrated circuit, then measurement can be conducted, but measurement difficulty increases and useful information about signal characteristics at integrated circuit pad is not provided
Solution Approach 1:
The patent introduces an intermediary measurement approach by using the receiver sampling circuit as a probe to indirectly measure signal characteristics at the integrated circuit pad. Instead of directly probing the pad which is difficult, the system uses the receiver's existing sampling infrastructure to capture voltage and timing information, thereby obtaining useful signal characteristics without the measurement difficulties associated with direct pad probing.
2Reliability
If global voltage margin and global frequency margin are measured, then system level margin information is obtained, but direct information about electrical parameters of specific communications link is not provided
Solution Approach 1:
The patent applies local quality by transitioning from global margin measurements to link-specific margin measurements. The receiver sampling circuit is configured to measure voltage and timing parameters for individual communications links rather than providing only system-level global margins. This localized measurement approach preserves specific electrical parameter information for each link while still contributing to overall system reliability assessment.
3Measurement precision
If receiver sampling circuit periodically samples signal, then voltage margin and timing margin can be determined, but additional measurement complexity is introduced
Solution Approach 1:
The patent implements self-service by utilizing the receiver sampling circuit's existing functionality for its intended purpose while simultaneously extracting margin information. The receiver sampling circuit, already designed to sample incoming signals for data recovery, is leveraged to also perform voltage and timing margin measurements. This eliminates the need for separate dedicated measurement equipment, thereby reducing overall system complexity while achieving precise margin determination.
Data Source
AI summary
A technique for characterizing a communications interface includes determining a voltage margin and a timing margin of the interface based on data sampled by a sampling device of a receiver of the interface. In at least one embodiment of the invention, a method for determining margin associated with a receiver circuit of an integrated circuit includes periodically sampling a signal over a time period by a receiver sampling circuit of the receiver circuit to generate a sampled version of the signal. The method includes incrementally varying a value of the parameter associated with the signal. The varying of the parameter is through a range of values of the parameter over the time period. The method includes determining a margin value of the receiver circuit associated with the parameter based, at least in part, on the sampled version of the signal.