Apparatus and methods for removing a large-signal voltage offset from a biomedical signal
Inventors
Drakulic, Budimir S. • FAKHAR, Sina • Foxall, Thomas G. • VLAJINIC, Branislav
Assignees
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Publication Number
US-11617530-B2
Publication Date
2023-04-04
Expiration Date
Abstract
Apparatus and methods remove a voltage offset from an electrical signal, specifically a biomedical signal. A signal is received at a first operational amplifier and is amplified by a gain. An amplitude of the signal is monitored, by a first pair of diode stages coupled to an output of the first operational amplifier, for the voltage offset. The amplitude of the signal is then attenuated by the first pair of diode stages and a plurality of timing banks. The attenuating includes limiting charging, by the first pair of diode stages, of the plurality of timing banks and setting a time constant based on the charging. The attenuating removes the voltage offset persisting at a threshold for a duration of at least the time constant. Saturation of the signal is limited to a saturation recovery time while the saturated signal is gradually pulled into monitoring range over the saturation recovery time.
Core Innovation
The disclosure relates to an EP acquisition/recording system that removes noise in electrocardiogram (ECG) and intracardiac (IC) signals by using a Wilson Central Terminal (WCT) circuit and a right-leg drive (RLD) circuit. The WCT circuit is coupled to two limb electrodes and operates as a reference for unipolar IC leads, and the RLD circuit is coupled to a third limb electrode to process signal reference and noise-related components.
The system includes a twin-T network coupled to the RLD circuit. The twin-T network comprises a first twin-T circuit coupled to a second twin-T circuit and an operational amplifier, where a node of the first twin-T circuit is coupled to a first input of the operational amplifier, the two limb electrodes are coupled to a second input of the operational amplifier, and an output of the operational amplifier is coupled to an input of the RLD circuit.
The node of the second twin-T circuit is coupled to the output of the operational amplifier, so the operational amplifier output drives the RLD while the twin-T network nodes shape the filtered behavior. In the described noise removal approach, the twin-T network enhances common-mode rejection at selected power-mains harmonic frequencies, including common-mode reference removal associated with the WCT/RLD architecture.
Claims Coverage
The independent claim defines an ECG/IC noise-removal system using a WCT reference for unipolar IC leads combined with an RLD circuit and a twin-T network processed through an operational amplifier. The claim set includes six dependent claims that refine the RLD behavior and the twin-T network’s harmonic/common-mode rejection filtering behavior.
Wilson Central Terminal reference with unipolar IC leads
A Wilson Central Terminal (WCT) circuit coupled to two limb electrodes, wherein the WCT circuit operates as a reference for unipolar IC leads.
Right-leg drive coupled to third limb electrode
A right-leg drive (RLD) circuit coupled to a third limb electrode.
Twin-T network with operational amplifier between twin-T nodes and RLD input
A twin-T network coupled to the RLD circuit, comprising a first twin-T circuit coupled to a second twin-T circuit and an operational amplifier, wherein a node of the first twin-T circuit is coupled to a first input of the operational amplifier, the two limb electrodes are coupled to a second input of the operational amplifier, and an output of the operational amplifier is coupled to an input of the RLD circuit; and wherein a node of the second twin-T circuit is coupled to the output of the operational amplifier.
Right-leg drive removing common-mode voltage
An RLD circuit configured to remove common mode voltage from an input signal to the RLD circuit.
Right-leg drive limiting current to third limb electrode
An RLD circuit configured to prevent current with an amplitude greater than one microampere from flowing to the third limb electrode.
Notch filter located in twin-T feedback path
A twin-T network having a notch filter located in its feedback path.
Enhanced common-mode rejection at power-mains harmonics
A twin-T network configured to enhance common-mode rejection at a first harmonic and a third harmonic of power mains.
Power-mains harmonic frequencies set to 60 Hz and 180 Hz
A first harmonic frequency of 60 Hz and a third harmonic frequency of 180 Hz.
Overall, the claim coverage centers on the combination of a WCT reference for unipolar IC leads, an RLD circuit coupled to a third limb electrode, and a twin-T network processed using an operational amplifier between twin-T nodes and the RLD input, with dependent features refining common-mode removal, current limiting, and twin-T notch/filtered enhancement at power-mains harmonics (including 60 Hz and 180 Hz).
Stated Advantages
Documented Applications
No documented applications found
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