Evoked Signal Sensing With Adjustable DC Offset Compensation
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Solution Overview
Problem
Existing electrical stimulation systems face challenges in accurately sensing evoked signals due to saturation of sense amplifiers caused by strong stimulation signals, leading to reduced signal-to-noise ratio and limited information retrieval from evoked signals.
Innovation Solution
Implementing a DC offset compensation circuit that dynamically adjusts its compensation current magnitude during stimulation and sensing windows, reducing or halting compensation during sensing windows to prevent amplifier saturation and enhance signal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DC offset compensation is provided at high magnitude during stimulation, then amplifier saturation is prevented, but signal-to-noise ratio deteriorates during sensing window
Solution Approach 1:
The DC offset compensation circuit dynamically adjusts its compensation current magnitude based on the operational phase. During stimulation, high magnitude compensation prevents amplifier saturation. During sensing windows, the compensation magnitude is reduced to no more than one-third of the stimulation level, optimizing signal-to-noise ratio while maintaining adequate offset compensation.
Solution Approach 2:
The system changes the compensation current parameter based on time phase. The processing system directs the DC offset compensation circuit to provide compensation at a first magnitude during stimulation and at a second magnitude (no more than one-third of the first) during sensing windows, thereby adapting the parameter to operational requirements.
2Measurement precision
If DC offset compensation is reduced during sensing window, then signal-to-noise ratio improves, but amplifier saturation risk increases
Solution Approach 1:
The system dynamically adjusts DC offset compensation based on operational phase. During sensing windows, compensation is reduced to no more than one-third of the stimulation level to optimize signal-to-noise ratio, while the processing system monitors conditions to prevent saturation.
Solution Approach 2:
The processing system monitors the operational state and directs the DC offset compensation circuit accordingly. During sensing windows, the system provides feedback to reduce compensation magnitude to optimize signal quality, while maintaining sufficient compensation to prevent saturation through continuous monitoring.
3Reliability
If continuous DC offset compensation is provided, then amplifier saturation is consistently prevented, but evoked signal detection accuracy deteriorates
Solution Approach 1:
The system implements periodic adjustment of DC offset compensation based on the stimulation-sensing cycle. During stimulation, high magnitude compensation prevents saturation. During sensing windows, compensation is reduced to no more than one-third of the stimulation level to enhance evoked signal detection accuracy, creating a periodic pattern that optimizes both saturation prevention and signal quality.
Data Source
AI summary
A stimulation system includes a stimulation generation system to provide stimulation; an evoked signal sensing system to receive an evoked signal from the tissue in response to the stimulation; and a processing system. The evoked signal sensing system includes a sense amplifier circuit and a DC offset compensation circuit configured to provide DC offset compensation at an input of the sense amplified circuit. The processing system is configured to, during the providing of the stimulation, direct the DC offset compensation circuit to provide, DC offset compensation at a first magnitude; and, after the providing of the stimulation and during a sensing window for the evoked signal, either a) direct the DC offset compensation circuit to provide DC offset compensation at a second magnitude that is no more than one-third of the first magnitude or b) direct the DC offset compensation circuit to provide no DC offset compensation.