Dual-Range Sense Amplifier for Neural Sensing Amid Stimulation Artifacts
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Solution Overview
Problem
Implantable neurostimulator devices face challenges in accurately sensing neural responses due to stimulation artifacts, which complicate the detection of small-amplitude neural signals riding on significant background voltages.
Innovation Solution
The implementation of a sense amplifier circuitry with low-voltage and high-voltage options, selectable based on input voltage magnitude, and DC offset compensation circuitry to enhance neural signal detection, allowing for improved sensing of neural responses amidst stimulation artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single voltage-level sense amplifier is used, then the device complexity is reduced, but the measurement precision deteriorates due to inability to accurately sense both small-amplitude neural signals and large stimulation artifacts
Solution Approach 1:
The system dynamically switches between a low-voltage sense amplifier and a high-voltage sense amplifier based on the amplitude of the input signal. The low-voltage amplifier is used for detecting small-amplitude neural signals with high precision, while the high-voltage amplifier is activated when large-amplitude stimulation artifacts are present, preventing saturation and maintaining measurement accuracy across varying signal conditions.
Solution Approach 2:
The invention changes the operating voltage parameter of the sense amplifier circuit by selecting between two distinct amplifier configurations. The low-voltage amplifier operates with a voltage range suitable for precise neural signal detection, while the high-voltage amplifier operates with an expanded voltage range to accommodate stimulation artifacts, thereby optimizing measurement precision for different signal amplitudes.
2Object-affected harmful factors
If high-voltage amplification is always used, then the ability to handle stimulation artifacts is improved, but the measurement precision of small neural signals deteriorates due to excessive gain and noise
Solution Approach 1:
The system dynamically adjusts the voltage operating range of the sense amplifier based on the detected signal amplitude. When stimulation artifacts are detected (large voltage swings), the high-voltage amplifier is activated to prevent saturation and handle the harmful interference. When only small neural signals are present, the low-voltage amplifier is used to maintain high measurement precision and minimize noise, thereby adaptively managing the harmful factors without sacrificing accuracy.
3Adaptability or versatility
If dual sense amplifier circuitry is implemented, then the adaptability to different signal conditions is improved, but the device complexity increases
Solution Approach 1:
The sense amplifier functionality is segmented into two distinct amplifier circuits: a low-voltage sense amplifier optimized for small-amplitude neural signals and a high-voltage sense amplifier optimized for large-amplitude stimulation artifacts. This segmentation allows each amplifier to be independently optimized for its specific operating range, improving overall adaptability while maintaining manageable complexity through functional division.
Solution Approach 2:
The system performs preliminary assessment of the input signal amplitude to determine which amplifier should be activated. By evaluating the signal characteristics before full amplification, the system can pre-select the appropriate amplifier configuration, ensuring optimal performance for the detected signal conditions and simplifying the control logic through proactive decision-making.
Data Source
AI summary
Sense amplifier (amp) circuitry for an implantable stimulator device is disclosed useful for sensing neural responses or other voltages in a patient's tissue. The sense amp circuitry comprises a low-voltage and a high-voltage sense amp circuit, either of which may be selected based on an assessment of the magnitude of the voltage at either or both of the inputs connected to selected sensing electrodes. The assessed magnitude, as determined by monitoring circuitry, can be processed by an algorithm to select use of one of the sense amp circuits, selecting the low-voltage sense amp circuit when the magnitude(s) are lower, and the high-voltage sense amp circuit when the magnitude(s) are higher. Furthermore, DC offset compensation circuitry is disclosed to equate the DC levels of the inputs, which may only operate when the high-voltage sense amp is selected.