Adaptive ADC Using Signal Prediction to Reduce Comparator Count
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Solution Overview
Problem
Existing high-speed analog-to-digital converters (ADCs) face challenges in power and size efficiency, particularly in high-speed applications requiring multiple bits, as they consume excessive power and chip area due to the need for numerous comparators, which degrades performance and is unsuitable for low-power applications.
Innovation Solution
The implementation of adjustable comparators with dynamically set reference voltages based on signal prediction, allowing for adaptive adjustment of comparator settings to match predicted voltage ranges, reducing the number of comparators required while maintaining resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional flash ADC with O(2^N) comparators is used to achieve N-bit precision, then measurement precision is improved, but device complexity and power consumption increase exponentially
Solution Approach 1:
The patent implements a dynamic comparator bank where comparators are selectively enabled or disabled based on the current conversion stage and signal characteristics. Instead of all O(2^N) comparators being active simultaneously, the system dynamically activates only the necessary subset of comparators for each conversion cycle, reducing power consumption and effective device complexity while maintaining N-bit precision capability
Solution Approach 2:
The comparator bank is segmented into multiple groups or stages, where each segment handles a specific portion of the conversion process. This segmentation allows the system to activate only relevant segments for each conversion operation, reducing the effective number of active comparators from O(2^N) to a manageable subset, thereby addressing both power consumption and device complexity concerns
2Measurement precision
If conventional flash ADC with O(2^N) comparators is used to achieve N-bit precision, then measurement precision is improved, but power consumption increases exponentially
Solution Approach 1:
The system employs dynamic power management for the comparator bank, where comparators are selectively powered on or off based on conversion requirements. This dynamic activation reduces the average power consumption from exponential O(2^N) to a linear or logarithmic relationship with respect to N-bit precision, as only necessary comparators consume power during each conversion operation
Solution Approach 2:
The comparator bank operates in periodic cycles where different subsets of comparators are activated in different time periods. This periodic activation pattern ensures that at any given moment, only a fraction of the total O(2^N) comparators are consuming power, while maintaining the capability to achieve N-bit precision when all comparators are needed, thus reducing overall power consumption
3Speed
If flash ADC is used for high-speed applications, then speed is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent implements a dynamic comparator activation mechanism that enables high-speed conversion by pre-enabling or pre-configuring the necessary comparators based on predicted or previously observed signal ranges. This dynamic preparation reduces the effective complexity during the critical conversion window while maintaining high-speed operation, as the system only needs to manage a subset of comparators at any given high-speed moment
Data Source
AI summary
Methods and apparatuses are described for performing adaptive analog-to-digital conversion and time-to-delay conversion by using signal prediction to adjust reference voltages of adjustable comparators.