On-Chip Oscilloscope Clock Sweeping for Eye Pattern Correlation
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Solution Overview
Problem
Existing on-chip oscilloscopes for communication channels face challenges in accurately measuring eye patterns and error rates due to disruption of the receiver's normal function when sweeping voltage offsets and phase signals, and they often require expensive comparators or consume valuable area on integrated circuits.
Innovation Solution
An integrated circuit design that includes an on-chip oscilloscope with a phase rotator and offset circuit, allowing for simultaneous determination of eye patterns and error rates without disrupting the receiver's function, using two comparators to generate digital values based on varied voltage offsets and phase-synchronized clock signals, and control logic to sweep across ranges of values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple comparators are used in an on-chip ADC to obtain sufficient resolution, then measurement precision is improved, but device cost and area consumption increase
Solution Approach 1:
The patent uses a single comparator to generate digital values that are then processed through histogram analysis to create eye patterns. Instead of using multiple comparators to directly achieve high resolution, the system creates multiple measurements using a single comparator and synthesizes the high-resolution information through statistical processing of the histogram data, effectively copying the measurement function across multiple iterations with a single hardware component
Solution Approach 2:
The patent combines the oscilloscope functionality with the existing single comparator in the data path. By merging the eye pattern measurement function with the existing comparator resource, the system achieves sophisticated measurement capabilities without adding multiple expensive comparators, integrating multiple functions into a single hardware element
2Adaptability or versatility
If voltage offset and phase sweeping is performed to measure eye patterns, then measurement capability is improved, but receiver function is disrupted
Solution Approach 1:
The patent implements periodic sweeping of voltage offset and phase values to build up histogram data for eye pattern measurement. The control logic systematically varies these parameters over multiple measurement cycles, accumulating statistical information that forms the complete eye pattern, allowing comprehensive measurement through periodic parameter variation
Solution Approach 2:
The system performs preliminary histogram accumulation by collecting digital values across multiple voltage offset and phase combinations before final eye pattern generation. This preliminary data collection phase builds the statistical foundation needed for accurate eye pattern reconstruction without interrupting the overall receiver operation
3Device complexity
If the comparator is located after an equalizer in on-chip oscilloscopes, then signal processing is simplified, but diagnostic capability is reduced
Solution Approach 1:
The patent inverts the conventional approach by placing the comparator before the equalizer in the signal path. This reversal allows the comparator to measure the raw signal characteristics before equalization processing, providing diagnostic information about the channel conditions and signal quality that would otherwise be obscured by the equalizer's corrective actions
Data Source
AI summary
An integrated circuit that includes a receive data path is described. The receive data path: equalizes a received analog signal, converts the resulting equalized analog signal to digital data values based on a clock signal, and recovers the clock signal in the digital data values. The integrated circuit also includes an on-chip oscilloscope. The oscilloscope includes: two comparators, a phase rotator that outputs an oscilloscope clock signal whose phase can be varied relative to that of the recovered clock signal, and an offset circuit that outputs a voltage offset. Based on the voltage offset and the oscilloscope clock signal, the comparators output digital values which can be used to determine eye patterns that correspond to the analog signal before and after equalization. The eye patterns can then be correlated with an error rate associated with the received data.