Compliance Voltage Detector Circuit for Implantable Stimulators
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Solution Overview
Problem
Implantable tissue stimulators face challenges in maintaining accurate current delivery due to varying impedance between electrodes, leading to potential overvoltage conditions and reduced battery life, as existing systems lack effective compliance voltage monitoring and adjustment mechanisms.
Innovation Solution
A compliance voltage monitoring apparatus and method that utilize threshold detectors and a coincidence indicator to detect non-compliance conditions by comparing electrode voltages to high-side and low-side threshold voltages, ensuring accurate current delivery and minimizing power consumption by adjusting the supply voltage accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If compliance voltage monitoring is implemented, then current delivery accuracy is improved, but device complexity increases
Solution Approach 1:
The compliance voltage monitoring function is segmented into separate high-side and low-side threshold detectors that operate independently. Each detector monitors specific voltage ranges, allowing the system to achieve comprehensive monitoring without requiring a single complex monitoring circuit. The segmentation enables modular design where each detector can be optimized for its specific voltage range.
Solution Approach 2:
The patent introduces compliance voltage detectors as intermediary components between the voltage generation circuitry and the load. These detectors act as mediators that monitor voltage levels and provide compliance information without directly interfering with the current delivery path. The coincidence indicator serves as another intermediary that integrates information from multiple detectors to determine overall system compliance.
2Measurement precision
If supply voltage is increased to maintain current delivery, then current delivery accuracy is improved, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the supply voltage based on real-time compliance monitoring. When voltage compliance is maintained, the system operates at optimal voltage levels for accurate current delivery. When compliance violations are detected, the system can adjust voltage levels to prevent overvoltage conditions. This dynamic adjustment allows the system to maintain current delivery accuracy while minimizing power consumption by avoiding unnecessarily high voltage operation.
Solution Approach 2:
The patent implements feedback through compliance voltage detectors that continuously monitor voltage levels and provide information back to the control system. This feedback mechanism enables the system to detect when voltage is approaching unsafe levels and adjust operation accordingly. The feedback loop allows the system to maintain accurate current delivery by adjusting voltage only when necessary, thereby reducing overall power consumption compared to continuous high-voltage operation.
3Reliability
If compliance monitoring is added, then reliability is improved, but device complexity increases
Solution Approach 1:
The reliability enhancement is achieved through segmentation of the monitoring function into separate high-side and low-side detectors. Each detector is dedicated to monitoring specific voltage conditions, which simplifies the design compared to a single comprehensive monitoring circuit. The segmentation allows for independent optimization of each detector and enables parallel operation, improving reliability without proportionally increasing overall complexity.
Solution Approach 2:
The system provides beforehand cushioning by continuously monitoring voltage compliance before dangerous overvoltage or undervoltage conditions can cause damage. The detectors are positioned to detect compliance violations early in the voltage swing, allowing preventive action to be taken. This prior cushioning approach improves reliability by preventing failures before they occur, rather than relying on complex protection circuits that only activate after damage has occurred.
Data Source
AI summary
A system, method, and circuit to monitor a compliance voltage in an implantable stimulator device. An implantable medical device with a compliance voltage detector to monitor the voltage used by an output current source/sink circuit to ensure proper circuit performance while limiting power use.