Compliance voltage monitoring and adjustment in an implantable medical device using low side sensing
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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 optimal voltage levels for reliable and efficient stimulation therapy without wasting power.
Innovation Solution
Implementing a system for compliance voltage monitoring and adjustment that includes a translator circuit to convert electrode node voltages to a common reference, allowing for precise assessment and adjustment of compliance voltage based on measured voltage drops across digital-to-analog converter circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compliance voltage is increased to ensure reliable stimulation therapy delivery, then therapy reliability is improved, but power consumption increases causing energy wastage
Solution Approach 1:
The patent implements dynamic compliance voltage adjustment where the voltage level is continuously modified based on real-time pulse amplitude changes. The system transitions from static voltage levels to dynamic adaptation, allowing the compliance voltage to increase when pulse amplitudes increase and decrease when pulse amplitudes decrease, thereby maintaining reliability while minimizing energy wastage.
Solution Approach 2:
The patent employs feedback mechanisms where voltage drops across the digital-to-analog converter circuits are measured and used to assess compliance voltage levels. This feedback loop enables the system to automatically adjust compliance voltage based on actual circuit performance, ensuring optimal voltage levels are maintained without excessive power consumption.
2Loss of energy
If compliance voltage is continuously monitored and adjusted to match pulse amplitude changes, then power efficiency is improved, but device complexity increases
Solution Approach 1:
The patent merges the compliance voltage monitoring function with the existing digital-to-analog converter circuitry by using the same voltage drop measurement mechanism for both purposes. This integration eliminates the need for separate monitoring circuits, reducing overall device complexity while maintaining power efficiency.
Solution Approach 2:
The voltage drop measurement mechanism serves multiple functions: it assesses compliance voltage levels for power management and simultaneously provides information about pulse amplitude changes. This multi-functionality reduces the need for additional dedicated circuits, thereby limiting the increase in device complexity.
3Measurement precision
If translator circuitry is added to convert electrode node voltages to common reference, then voltage measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces translator circuitry as an intermediary component that converts electrode node voltages to a common reference frame. This intermediary mechanism enables precise voltage measurements across different circuit nodes without requiring complex direct measurement arrangements, thereby improving measurement precision with manageable complexity.
Data Source
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.