Implantable Device Clock Calibration via Telemetry Downlink
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Solution Overview
Problem
Implantable medical devices face challenges in maintaining high accuracy clocking signals while minimizing power consumption, as low-power oscillators suffer from inaccuracies due to poor long-term stability and environmental factors, which is crucial for accurate sensing and therapy delivery but consumes substantial current.
Innovation Solution
A calibration routine is periodically performed to adjust the low-power local clock within the implantable medical device using an accurate clock signal, allowing for continuous operation and reducing current drain by compensating for deviations and errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high accuracy oscillator is used to generate clocking signals, then clocking accuracy is improved, but power consumption increases substantially
Solution Approach 1:
The patent implements periodic calibration routines where the high accuracy oscillator is activated only intermittently to recalibrate the low-power oscillator, rather than running continuously. This allows the system to maintain accurate timing while minimizing power consumption by the high accuracy oscillator.
Solution Approach 2:
The patent introduces a low-power oscillator as an intermediary that runs continuously at low power consumption, while the high accuracy oscillator serves as a periodic reference source. The low-power oscillator mediates between the high accuracy reference and the continuous timing requirements, reducing overall power consumption while maintaining accuracy.
2Use of energy by moving object
If a low-power oscillator is used to minimize current drain, then power consumption is reduced, but clocking accuracy deteriorates due to poor long-term stability
Solution Approach 1:
The patent implements a feedback mechanism where the low-power oscillator's output is periodically compared against the high accuracy oscillator, and calibration factors are applied to correct drift. This feedback loop maintains clocking accuracy despite the low-power oscillator's inherent instability.
Solution Approach 2:
The patent dynamically adjusts parameters of the low-power oscillator based on calibration data, including frequency scaling factors and timing corrections. These parameter changes compensate for the oscillator's drift and instability, maintaining accurate clocking while operating at low power.
Data Source
AI summary
An implantable medical device includes a local clock generator for generating a system clock signal. The local clock generator is periodically calibrated to maintain accuracy of the generated system clock signal. A clocking circuit is coupled to the local clock generator to provide the calibration factor for calibrating the local clock generator. The implantable medical device receives an accurate clock signal that is transmitted from an external device and the accurate clock signal is provided to the clocking circuit. The system clock signal is also provided to the clocking circuit and a computation is performed to derive the calibration factor.