ADC Sampler Timing Alignment Using Bubble-Derivative Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-speed analog to digital converters (ADCs) face challenges in maintaining accurate aperture timing due to sampler offsets, leading to errors such as 'bubbles' or 'sparkle codes' in the output, which disrupt data conversion and reduce the effective resolution of ADCs.
Innovation Solution
A method for background calibration of aperture center errors is introduced, where a signal derivative is calculated at the time of detected low sampler outputs between high outputs, and the timing of selected samplers is adjusted to compensate for timing errors, effectively removing 'bubbles' without disrupting normal signal flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If foreground calibration is performed to correct aperture timing errors, then measurement precision is improved, but productivity deteriorates due to disruption of normal signal flow
Solution Approach 1:
The patent applies preliminary action by performing aperture timing calibration in the background without disrupting normal ADC operation. The calibration process is initiated and executed while the ADC continues to convert data, allowing timing errors to be corrected before they significantly impact performance, thus maintaining both measurement precision and productivity
Solution Approach 2:
The patent implements continuity of useful action by enabling the ADC to simultaneously perform normal data conversion and aperture timing calibration. The calibration process operates in the background without interrupting the forward flow of data through the ADC, ensuring continuous productive operation while progressively correcting timing errors
2Productivity
If background calibration is performed to maintain continuous operation, then productivity is maintained, but measurement precision deteriorates due to ongoing timing errors
Solution Approach 1:
The patent applies feedback by continuously monitoring the ADC output for bubble patterns that indicate aperture timing errors. The system uses this feedback information to iteratively adjust and correct the timing of individual samplers, progressively improving measurement precision while maintaining continuous operation and productivity
Solution Approach 2:
The patent implements self-service by enabling the ADC to automatically detect and correct its own aperture timing errors through background calibration. The system monitors its own output for error patterns and autonomously adjusts sampler timing without external intervention, maintaining both productivity and improving precision over time
3Productivity
If multiple samplers are used to increase conversion speed, then productivity is improved, but measurement precision deteriorates due to differential aperture errors between samplers
Solution Approach 1:
The patent applies local quality by individually calibrating each sampler's timing based on its specific aperture error characteristics. Instead of treating all samplers uniformly, the system identifies and corrects timing errors for each individual sampler, ensuring that local timing variations do not degrade overall measurement precision while maintaining high conversion speed
Data Source
AI summary
A method of background calibration of aperture center errors in a data communication system is provided. In an implementation, in response to detection of a low sampler output (“0”) in between two high sampler outputs (“1”), the method includes: calculating a signal derivative of an ADC output signal at the time of the detected low output; and adjusting timing at a selected sampler based on the calculated signal derivative. In an example implementation, the method includes watching for bubbles in the thermometer code output, and estimating the first derivative of the signal at the time of the bubble, then estimating the sign of the errors. In an example implementation, the errors are used in a control loop to reduce the aperture center error.