Adaptive SAR A/D Conversion for Low-Power Implantable Monitoring
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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 signal monitoring.
Innovation Solution
The implementation of an adaptive successive approximation register (ASAR) in A/D converters that adjusts the number of bits used for conversion based on previous results, allowing for reduced power consumption by using fewer bits during periods where signals remain within a smaller range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a full-bit A/D converter is used to maintain high measurement precision, then signal conversion accuracy is improved, but power consumption increases significantly
Solution Approach 1:
The patent applies dynamics by making the number of bits in the A/D converter adaptive rather than fixed. The converter dynamically adjusts its resolution based on the actual signal characteristics being measured. When signals exhibit low variability, the converter uses fewer bits to reduce power consumption, while maintaining full precision when signals require higher accuracy, thus resolving the contradiction between measurement precision and power consumption.
Solution Approach 2:
The patent changes the parameter of bit resolution from a static full-bit configuration to a variable parameter that adapts to signal conditions. By modifying the number of bits used in conversion based on measured signal characteristics, the system achieves both low power consumption during stable conditions and high precision when needed, directly addressing the contradiction between these two requirements.
2Use of energy by moving object
If the number of bits is reduced to lower power consumption, then energy usage decreases, but measurement precision deteriorates
Solution Approach 1:
The system dynamically changes the bit resolution parameter based on signal characteristics. When signals are stable and require less precision, fewer bits are used to reduce power consumption. When precision requirements increase, the system automatically adjusts to use more bits, thus maintaining measurement accuracy while optimizing energy usage across different operating conditions.
Solution Approach 2:
The A/D converter transitions from a static full-bit mode to a dynamic adaptive mode where the number of bits changes in response to signal variability. This dynamic adjustment allows the system to consume less power during periods of low signal change while preserving the capability to maintain high precision when signal accuracy becomes critical.
3Measurement precision
If full-bit conversion is performed continuously, then signal accuracy is maintained, but conversion cycle time increases
Solution Approach 1:
The patent implements dynamic adaptation of the conversion process by adjusting the number of bits based on signal characteristics. When signals are stable, the converter uses fewer bits and completes conversions more quickly, reducing the conversion cycle time. When signal variability increases, the system dynamically increases precision, thus balancing conversion speed and accuracy based on actual needs.
Solution Approach 2:
The system changes the conversion parameter (number of bits) from a constant full-bit value to a variable value that adapts to signal conditions. This parameter change enables faster conversion cycles during stable periods while maintaining the option to use full precision when signal accuracy becomes critical, thereby reducing overall conversion time without permanently sacrificing measurement precision.
Data Source
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AI summary
A medical device configured to convert an analog signal using an adaptable bit number. 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 bit number so that on at least a portion of the conversion cycles an adapted number of bits spanning a portion of the full scale range less than the total number of bits is used by the A/D converter to convert the analog signal.