Implantable Pulse Generator Low-Side Sensing for Compliance Voltage Control
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Solution Overview
Problem
Managing compliance voltage in implantable pulse generators is challenging due to rapid and significant alterations in stimulation pulse amplitudes, making it difficult to ensure reliable and efficient power usage without wasting battery power.
Innovation Solution
Implementing a system for specifying which stimulation pulses are relevant for compliance voltage monitoring and adjustment by setting a compliance monitor bit in the program, allowing for efficient and timely adjustments to the compliance voltage based on measured voltage drops across the PDAC and NDAC circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compliance voltage is continuously monitored and adjusted to ensure reliable pulse formation, then therapy delivery reliability is improved, but device complexity and power consumption increase
Solution Approach 1:
The system performs preliminary action by measuring compliance voltage during specific pulse phases (particularly during the ramp-up phase of bipolar pulses) before potential problems occur. The compliance monitor bit is set in advance to trigger measurements at critical moments, allowing the system to proactively adjust voltage levels rather than reactively responding to failures.
Solution Approach 2:
The system implements feedback by continuously monitoring compliance voltage through detector circuitry that feeds voltage information back to the controller. When voltage drops below thresholds during stimulation pulses, the controller receives feedback signals and automatically adjusts the compliance voltage generator to maintain reliable pulse delivery, creating a closed-loop control system.
2Loss of energy
If compliance voltage is adjusted frequently to match changing stimulation requirements, then power efficiency is improved, but loss of time for monitoring and adjustment increases
Solution Approach 1:
The system applies periodic action by monitoring compliance voltage at specific intervals during pulse delivery rather than continuously. The compliance monitor bit triggers measurements at key moments in the pulse cycle (such as during the active stimulation phase), allowing the system to adjust voltage periodically rather than constantly, reducing both power consumption and adjustment time while maintaining efficiency.
Solution Approach 2:
The system implements dynamics by making the compliance voltage adjustable and adaptive rather than fixed. The controller dynamically modifies voltage levels based on real-time pulse characteristics and tissue response, allowing the system to optimize power efficiency for each specific stimulation condition while responding quickly enough to maintain therapy delivery reliability.
3Use of energy by stationary object
If compliance voltage monitoring is performed during all stimulation pulses, then power usage efficiency is improved, but device complexity increases
Solution Approach 1:
The system applies segmentation by dividing the monitoring function into discrete, manageable components: a compliance monitor bit in the pulse program, detector circuitry with threshold comparators, and a controller that processes measurements. This segmented approach allows monitoring during specific pulse types without requiring a monolithic complex system, reducing overall device complexity while maintaining power efficiency.
Solution Approach 2:
The system implements self-service by using the stimulation pulse itself as the trigger for compliance voltage measurement. The pulse delivery circuitry naturally provides the timing signal needed to activate monitoring, eliminating the need for separate monitoring triggers or additional complex control logic. The system uses its own operational signals to initiate monitoring functions.
Data Source
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AI summary
An architecture is disclosed for an Implantable Pulse Generator having improved compliance voltage monitoring and adjustment software and hardware. Software specifies which stimulation pulses are to be measured as relevant to monitoring and adjusting the compliance voltage. During compliance voltage monitoring, "high-side" anode electrode node voltages referenced to the compliance voltage are considered as are "low-side" cathode electrode node voltages referenced to ground. Translation stages are used to convert only the anode electrode node voltages to ground as low-side signals. This allows compliance voltage monitoring and adjustment to occur using only low-side signals, which eases sensing and reduces design complexity.