Physiological signal acquisition system and method with improved noise and common mode rejection performance and signal quality
Inventors
Assignees
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Publication Number
US-11444646-B1
Publication Date
2022-09-13
Expiration Date
Abstract
The present invention relates to the acquisition, processing, and monitoring of signals, and particularly to the acquisition, processing, and monitoring of electrophysiological signals. More particularly, the present invention relates to the acquisition, processing, and monitoring electroencephalography (EEG) signals representing cortical/brain activity. Further, the present invention relates to a method and apparatus for acquiring such signals in the presence of electrical interference and noise. More particularly, the present invention relates to systems and methods for filtering out and rejecting electrical interference and noise while maintaining or improving the quality of the underlying physiological signal and preventing perturbation or introduction of artifacts into the physiological signal.
Core Innovation
The invention relates to an EEG physiological signal acquisition system with analog front-end circuitry configured to reject electrical interference and noise, including power frequency interference, while preserving low-frequency EEG signal quality. It addresses unwanted common-mode components that reduce measurement fidelity and introduce artifacts into EEG signals.
The system uses at least two bootstrapped filters, each including a resistor, a first capacitor and a second capacitor, together with a unity gain buffer. The second capacitor is driven so that it has substantially the same upper and lower alternating current voltage as when the EEG physiological signal enters the input, and is driven by a common mode signal or a physiological signal potential.
Each bootstrapped filter is directly connected to a common node of at least two amplifiers of an instrumentation amplifier, with the bootstrap filter external to the instrumentation amplifier. The bootstrapped filters are adapted to remove common mode signal from the physiological signal prior to the signal entering the instrumentation amplifier, and the system is adapted to have a common mode rejection ratio of 95 dB or greater.
Claims Coverage
The independent claims cover an EEG analog front-end acquisition system using external bootstrapped filters to remove common-mode signal before amplification, with a common mode rejection ratio of 95 dB or greater. The inventive features center on the bootstrapped filter structure and drive arrangement, direct connection to a common node of the instrumentation amplifier, external placement, and scalability by adding channels.
External bootstrapped filters drive second capacitor to same AC voltage for common-mode removal before instrumentation amplification
At least two bootstrapped filters, each comprising a resistor, a first capacitor and a second capacitor, and a unity gain buffer, wherein the resistor and first capacitor form a low-pass filter and the second capacitor is driven to have substantially the same upper and lower alternating current voltage as when the EEG physiological signal enters the input, the second capacitor being driven by a common mode signal or a physiological signal potential; and each bootstrapped filter being external to the instrumentation amplifier and adapted to remove common mode signal from the physiological signal prior to the signal entering the instrumentation amplifier.
Common-node connection of external bootstrapped filters to multi-amplifier instrumentation amplifiers
At least one instrumentation amplifier comprising at least two amplifiers, wherein each of the two bootstrapped filters is directly connected to a common node of the at least two amplifiers of the instrumentation amplifier.
Common mode rejection ratio adapted to be 95 dB or greater
The system is adapted to have a common mode rejection ratio of 95 dB or greater.
Scalable additional channels by adding bootstrapped filters and using existing channel as reference
The system is adapted to allow additional channels to be added by adding an additional bootstrapped filter and using an existing channel as a reference.
All independent claims require external bootstrapped filters with a resistor, a first capacitor, a second capacitor, and a unity gain buffer, with the second capacitor driven to match substantially the same AC voltage characteristic as the incoming EEG input. The filters are directly connected to a common node of at least two amplifiers within an instrumentation amplifier, remove common-mode signal before entry into the instrumentation amplifier, and the system is adapted to achieve a common mode rejection ratio of 95 dB or greater.
Stated Advantages
Common mode signal removal prior to the signal entering the instrumentation amplifier.
Common mode rejection ratio of 95 dB or greater.
Additional channels can be added by adding an additional bootstrapped filter and using an existing channel as a reference.
Documented Applications
No documented applications found
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