Range-Adaptive A/D Conversion for Low-Power Medical Signal Sensing
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Solution Overview
Problem
Implantable medical devices face challenges in reducing power consumption of analog-to-digital converters, which is crucial for device size reduction and battery longevity, as they require significant power for continuous monitoring of physiological signals.
Innovation Solution
A self-adjusting analog-to-digital converter that dynamically adjusts the number of bits used during conversion cycles, reducing the number of comparisons and thereby minimizing power consumption and conversion time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a full-scale A/D converter with total number of bits is used for continuous monitoring, then measurement precision is maintained, but power consumption increases significantly
Solution Approach 1:
The patent applies dynamics by making the number of bits used in A/D conversion variable rather than fixed. The system dynamically adjusts the number of comparisons based on the actual signal range detected, using fewer bits when the signal occupies a limited portion of the full scale range, and switching to more bits when the signal approaches the full range. This dynamic adaptation resolves the contradiction by maintaining measurement precision only when necessary while reducing power consumption during normal operation.
Solution Approach 2:
The system changes the parameter of bit resolution based on signal characteristics. By monitoring the signal range and adjusting the number of bits used in conversion, the system optimizes the balance between precision and power consumption. When the signal remains within a limited range, fewer bits suffice; when the signal expands to utilize the full scale, the system increases bit resolution accordingly.
2Use of energy by moving object
If the number of bits is reduced to lower power consumption, then energy efficiency improves, but measurement precision deteriorates
Solution Approach 1:
The system dynamically changes the bit resolution parameter based on the actual signal range. When the signal occupies only a portion of the full scale range, the system uses fewer bits for conversion, reducing power consumption while maintaining sufficient precision for the current signal level. This parameter adaptation ensures that precision is optimized for the actual measurement needs rather than always using maximum bits.
Solution Approach 2:
The patent implements dynamic adjustment of conversion precision. The system continuously monitors the signal range and adapts the number of bits used in each conversion cycle, making the precision level dynamic rather than static. This allows the system to use lower precision (fewer bits) when appropriate, conserving energy while maintaining adequate measurement accuracy.
3Device complexity
If a fixed number of bits is used for all conversion cycles, then device complexity is reduced, but adaptability to different signal ranges deteriorates
Solution Approach 1:
The A/D converter system performs self-service by automatically monitoring its own signal input and autonomously determining the appropriate number of bits to use for conversion. The system includes circuitry that detects the signal range and self-adjusts the conversion parameters without external intervention, enabling adaptability while keeping the control mechanism relatively simple through self-regulation.
Solution Approach 2:
The system employs feedback mechanisms where the output of the signal range detection is fed back to control the number of bits used in conversion. This feedback loop enables the system to adapt to different signal ranges automatically, improving versatility while maintaining manageable complexity through a closed-loop control structure.
Data Source
AI summary
A medical device and associated method convert an analog signal using an adaptable number of comparisons between the analog signal and a reference signal. The medical device includes an analog-to-digital (A/D) converter for receiving an analog signal. The A/D converter has a full scale range and a total number of bits spanning the full scale range. The A/D converter converts the analog signal to a digital signal over conversion cycles using an adaptable number of comparisons. For at least one of the conversion cycles, the adaptable number of comparisons is less than the total number of comparisons required to convert the analog signal over the full scale range of the A/D converter.