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Publication Number
US-11517245-B2
Publication Date
2022-12-06
Expiration Date
Abstract
A system for monitoring includes: multiple EEG sensors spatially positioned on a layer of tissue for capturing EEG signals of a patient; multiple amplifiers coupled with the EEG sensors for amplifying the captured signals; and a low frequency oscillator for generating a synchronizing signal which is distributed to the amplifiers for synchronizing the digitization of the captured signals; wherein each amplifier includes: a voltage controlled oscillator for an adjustable frequency reference; an analog to digital converter for converting the amplified signal to a digital value; and a microcontroller for controlling the frequency of the voltage controlled oscillator and operation of the analog to digital converter by using the synchronizing signal.
Core Innovation
The disclosure relates to an EEG monitoring synchronization approach in which a first oscillator generates a synchronizing signal and the synchronizing signal is transmitted to a plurality of amplifiers. Each amplifier is coupled to one or more EEG sensors and amplifies the captured EEG signals, while using a second oscillator and an analog to digital converter (ADC) for digitization. A microcontroller controls the frequency of the second oscillator and the operation of the ADC based on the synchronizing signal transmitted from the first oscillator.
To avoid distributing a high-speed clock signal, the disclosed system distributes the synchronizing signal as a low-frequency synchronizing signal via cables to the amplifiers. Each amplifier measures the synchronizing signal period using an internal timer with microsecond resolution and uses this measurement to calibrate the second oscillator frequency. The microcontroller adjusts the VCO-based second oscillator frequency and derives an ADC clock and convert start signals from the calibrated oscillator.
The disclosure emphasizes that using low-frequency synchronization and local oscillator calibration mitigates electromagnetic interference and safety-related disturbance effects, including EMI, ESD, and EFT. It further states that calibration using the VCO improves synchronization accuracy beyond about 1 microsecond and avoids beat-frequency artifacts. The system-level implementation is described with examples of a multi-channel EEG amplifier system, and a flowchart is provided for distributing the low-frequency synchronizing signal, measuring its period, adjusting the VCO, generating ADC signals, and ensuring identical oscillator frequencies across amplifiers.
Claims Coverage
Independent claim 1 covers an EEG monitoring system architecture with a first oscillator providing a synchronizing signal and, within each amplifier, a second oscillator and an ADC whose operation is controlled by a microcontroller in response to the synchronizing signal. No other independent claims are present in the provided claim list; therefore only one independent claim is identified.
Eeg monitoring system with synchronizing signal from a first oscillator
A plurality of EEG sensors capture patient EEG signals, a plurality of amplifiers amplify the captured EEG signals, and a first oscillator generates a synchronizing signal for distribution to the amplifiers.
Amplifier synchronizes a second oscillator and ADC operation based on the synchronizing signal
Each amplifier receives the synchronizing signal transmitted from the first oscillator, includes a second oscillator and an ADC coupled with the second oscillator to digitize the captured EEG signals, and includes a microcontroller configured to control the frequency of the second oscillator and an operation of the ADC based on the synchronizing signal.
The provided independent claim coverage focuses on synchronizing distributed EEG amplifiers by transmitting a synchronizing signal from a first oscillator, and using a per-amplifier microcontroller to control a second oscillator that drives ADC digitization, with synchronization and ADC operation tied to the synchronizing signal.
Stated Advantages
Eliminating high-speed clock distribution to reduce cost and power and mitigate EMI/ESD/EFT interference [as described in the provided summary content].
Improved synchronization accuracy beyond about 1 microsecond [as described in the provided summary content].
Avoidance of beat-frequency noise [as described in the provided summary content].
Documented Applications
EEG monitoring with a multi-channel amplifier example, including a 128-channel EEG amplifier system [as described in the provided summary content].
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