Level-Crossing ADC Threshold Prediction for Sparse-Signal Power Reduction
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Solution Overview
Problem
Analog-to-digital converters (ADCs), particularly level-crossing ADCs, consume significant power due to frequent comparisons with reference signals, which is inefficient, especially for sparse signals that spend most time near a common-mode value.
Innovation Solution
A predictive level-crossing ADC method and circuit that compares an input signal with either an upper or lower threshold level based on the previous sampling period's results, adjusting the threshold levels and reducing comparisons to minimize power consumption by determining which threshold level to use in subsequent sampling periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional level-crossing ADC compares input signal with both upper and lower threshold levels in every sampling period, then measurement precision is maintained, but power consumption increases significantly
Solution Approach 1:
The patent applies preliminary action by predicting the next threshold level to be compared based on the current input signal level and previous comparison results. The ADC circuit determines in advance which threshold (upper or lower) will be used in the next sampling period, avoiding unnecessary comparisons and reducing power consumption while maintaining measurement precision for sparse signals.
2Productivity
If Flash-ADC is used to achieve fast conversion speed, then productivity is improved, but power consumption increases significantly
Solution Approach 1:
The patent applies partial action by performing comparisons only when necessary - specifically, only comparing with the predicted threshold level when a level crossing is anticipated. For sparse signals that remain between threshold levels for extended periods, the ADC skips unnecessary comparisons, achieving significant power reduction while maintaining adequate conversion speed for the application.
3Use of energy by moving object
If the number of comparator operations is reduced for sparse signals, then power consumption decreases, but measurement precision may be compromised
Solution Approach 1:
The patent applies feedback by continuously monitoring the input signal level and using this information to dynamically adjust which threshold level will be compared in the next sampling period. The ADC circuit uses feedback from previous comparison results and current signal levels to intelligently predict future threshold selections, ensuring that measurements are taken at critical moments when level crossings occur, thus maintaining precision while reducing overall comparison count.
Data Source
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AI summary
A method for predictive level-crossing, LC, in an analog-to-digital converter, ADC, is provided. The method comprises the steps of comparing a first input signal sampled during a first sampling period with one of an upper threshold level and a lower threshold level to determine if a level crossing has occurred during said first sampling period. Which one of said two threshold levels that is compared with said first input signal is based on if a level crossing occurred during a prior sampling period directly prior to the first sampling period, and which one of the two threshold levels was compared to a prior input signal sampled during said prior sampling period.