A/D Converter Duty Control for Thermometer Code Bubble Reduction
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Solution Overview
Problem
Conventional A/D converters experience reduced conversion accuracy due to relative variations among comparators, leading to bubble errors in thermometer codes, which are often ignored, resulting in decreased accuracy and efficiency.
Innovation Solution
The A/D converter includes a duty adjustment circuit that detects bubbles in thermometer codes and adjusts the sampling and comparison times of comparators to minimize bubble generation by optimizing the duty ratio of the comparator control signal, ensuring accurate and efficient conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sampling time and comparison time are extended to improve accuracy, then the sampling and comparison accuracies improve, but the conversion speed decreases
Solution Approach 1:
The patent applies dynamics by making the duty ratio of the comparator control signal adjustable rather than fixed. The duty adjustment circuit dynamically modifies the duty ratio based on detected bubble errors, allowing the system to adapt the sampling and comparison time allocation to optimize both accuracy and speed under different operating conditions.
Solution Approach 2:
The patent changes the duty ratio parameter of the comparator control signal to resolve the contradiction. By adjusting this parameter, the system can allocate more time to sampling or comparison as needed, thereby improving accuracy without permanently sacrificing conversion speed. The duty ratio serves as a controllable parameter that balances the two competing requirements.
2Measurement precision
If the duty ratio of the comparator control signal is increased to extend sampling time, then sampling accuracy improves, but comparison time decreases leading to more bubbles
Solution Approach 1:
The patent implements feedback by detecting bubble errors in the thermometer codes and using this information to adjust the duty ratio. The bubble detection mechanism provides feedback about comparison accuracy, and the duty adjustment circuit uses this feedback to modify the duty ratio, creating a closed-loop system that automatically corrects accuracy issues.
Solution Approach 2:
The patent applies preliminary action by adjusting the duty ratio in advance based on predicted or detected bubble tendencies. Rather than waiting for bubbles to occur and then correcting them, the system proactively modifies the duty ratio to prevent bubble formation, thereby maintaining reliability before errors occur.
3Device complexity
If the duty ratio is fixed at 50% to simplify control, then the control circuit complexity is reduced, but the ability to optimize accuracy and speed is limited
Solution Approach 1:
The patent applies self-service by enabling the control circuit to automatically adjust its own duty ratio based on bubble detection feedback. The duty adjustment circuit monitors the thermometer codes for bubbles and autonomously modifies the duty ratio without requiring external intervention or complex manual control, allowing the system to self-optimize its performance.
Data Source
AI summary
An A/D converter includes a plurality of comparators that performs sampling of a plurality of reference voltages and analog input signals during a sampling time, and compares each of the plurality of reference voltages with each of the plurality of analog signals during a comparison time. The A/D converter detects bubbles in thermometer codes obtained from output signals of the plurality of comparators and adjusts a ratio of the sampling time and the comparison time of the plurality of comparators so as to reduce the bubbles.