ADC Threshold Background Calibration for Continuous Signal Conversion
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Solution Overview
Problem
Flash Analog to Digital Converters (ADCs) face challenges in maintaining linearly spaced thresholds due to offset variations over time, which degrade ADC performance and require frequent disruptions for calibration, disrupting normal signal processing.
Innovation Solution
A method for background calibration of threshold errors in ADCs using sampler statistics from foreground calibration as a reference, allowing continuous adjustment of comparator thresholds during normal operation without disrupting signal flow, ensuring linear spacing and minimizing offset variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If foreground calibration is performed to remove comparator offsets, then threshold linearity is improved, but normal signal processing is disrupted
Solution Approach 1:
The patent performs foreground calibration as a preliminary action during manufacturing or initialization to establish accurate threshold values. This preliminary calibration sets the baseline threshold linearity before normal operation begins, allowing the system to achieve high precision without continuous disruption of signal processing during operational phases.
Solution Approach 2:
The patent implements background calibration that operates continuously in the background during normal signal processing. This allows the useful action of signal conversion to continue uninterrupted while calibration adjustments are made simultaneously, resolving the contradiction between maintaining precision and ensuring continuous productivity.
2Reliability
If frequent calibration is performed to maintain threshold linearity, then ADC performance is improved, but system interruptions increase
Solution Approach 1:
The patent performs comprehensive calibration as a preliminary action during manufacturing or initialization, establishing accurate thresholds that remain valid for extended periods. This reduces the frequency of subsequent calibration interventions, minimizing system interruptions while maintaining ADC performance reliability.
Solution Approach 2:
The patent implements background calibration that operates continuously at low intensity during normal operation, rather than performing frequent discrete calibration interruptions. This continuous subtle adjustment maintains threshold linearity and ADC performance without causing significant system interruptions or time loss.
3Productivity
If comparator offsets are not calibrated, then signal processing continuity is maintained, but threshold spacing linearity degrades
Solution Approach 1:
The patent implements background calibration that operates continuously during normal signal processing, allowing both signal conversion and threshold calibration to proceed simultaneously. This ensures that threshold spacing linearity is maintained through continuous adjustment without interrupting the continuity of signal processing operations.
Solution Approach 2:
The patent enables the ADC system to perform self-calibration during normal operation through background calibration mechanisms. The system automatically adjusts comparator thresholds based on observed signal characteristics, maintaining precision without external intervention or disruption to signal processing continuity.
Data Source
AI summary
A method of background calibration of threshold errors in a data communication system is provided. In an implementation, the method uses sampler statistics just after foreground calibration as the reference signal in a control loop method to remove individual sampler offsets. In an implementation in which an analog to digital converter (ADC) includes a plurality of sub-ADCs, gain, offset, and individual threshold errors across parallel, time-interleaved sub-ADCs are minimized by establishing individual comparator statistics for the average sub-ADC after an initial foreground calibration, then forcing each individual comparator to maintain its statistics over time, in the background, by continuously adjusting its threshold.