Dynamic ADC Range Selection for High-Resolution Low-Power Conversion
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Solution Overview
Problem
Traditional analog to digital converters face challenges in increasing resolution without incurring excessive power and area consumption, and suffer from imperfections in thermometer codes due to noise and process differences, leading to increased complexity and costs.
Innovation Solution
The implementation of dynamic analog to digital converters with a comparator bank and a range selection filter that adjusts reference thresholds based on prior outputs and inter-symbol interference values, using either virtual or physical reference level shifting, and incorporating a Decision Feedback Equalization (DFE) circuit to mitigate noise and improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of comparators is increased to provide higher resolution, then the resolution is improved, but the power consumption and area consumption increase
Solution Approach 1:
The patent applies dynamic reference threshold adjustment where the reference thresholds are not fixed but are dynamically modified based on prior comparator outputs and inter-symbol interference values. This allows a single comparator to effectively perform multiple comparison levels over time, achieving high resolution without requiring multiple static comparators. The dynamic adjustment compensates for what would otherwise require numerous fixed comparators, thereby reducing power consumption while maintaining high resolution.
Solution Approach 2:
The patent introduces a temporal dimension to the comparison process by using past outputs to adjust current reference thresholds. Instead of using multiple comparators in parallel (spatial dimension), the system uses a single comparator across multiple time steps with dynamically adjusted references. This transforms the resolution achievement from a spatial parallel structure to a temporal sequential process, reducing the number of physical comparators needed.
2Measurement precision
If the number of comparators is increased to provide higher resolution, then the resolution is improved, but the area consumption increases
Solution Approach 1:
The system dynamically adjusts reference thresholds based on previous outputs and interference values, allowing a single comparator to achieve the resolution that would traditionally require multiple static comparators. This dynamic approach consolidates the functionality of multiple comparators into one, significantly reducing the chip area required for the comparator bank while maintaining high resolution through temporal processing.
Solution Approach 2:
The patent transitions from a spatial arrangement of multiple comparators to a temporal sequence of comparisons with a single comparator. By utilizing the time dimension and feedback from previous outputs, the system achieves high resolution without the area overhead of a large comparator bank, effectively trading spatial complexity for temporal processing.
3Measurement precision
If the difference between successive reference voltages is reduced to increase resolution, then the resolution is improved, but the thermometer code becomes imperfect due to noise and process differences
Solution Approach 1:
The patent implements feedback by using prior comparator outputs to adjust the current reference threshold. This feedback mechanism allows the system to adapt to noise and process variations dynamically. When noise or process differences cause imperfect thermometer codes, the feedback from previous correct comparisons helps correct the reference threshold for the current comparison, thereby maintaining code quality even with small voltage differences between successive references.
Solution Approach 2:
The system performs preliminary adjustment of the reference threshold based on prior outputs before performing the current comparison. By anticipating potential issues from noise or process variations and pre-adjusting the reference based on previous results, the system prevents thermometer code imperfections before they occur, ensuring higher reliability in the digital output.
4Measurement precision
If the difference between successive reference voltages is reduced to increase resolution, then the resolution is improved, but the encoder complexity increases substantially
Solution Approach 1:
The feedback mechanism using prior outputs to adjust reference thresholds simplifies the encoding process. Instead of requiring a complex encoder to handle imperfect thermometer codes from multiple comparators, the feedback-based single-comparator approach produces more reliable outputs directly, reducing the encoding complexity while maintaining high resolution.
Data Source
AI summary
Various embodiments of the present invention provide systems and methods for analog to digital conversion. For example, an analog to digital converter is disclosed that includes an analog input that is provided to a comparator bank. The comparator bank receives a reference indicator, and is operable to provide a current output based at least in part on a comparison of the analog input with a reference threshold corresponding to the reference indicator. The analog to digital converter further includes a range selection filter that is operable to receive the current output and to generate the reference indicator based at least in part on a prior output of the comparator bank.