Implantable signal amplifying circuit for electroneurographic recording
First Claim
1. An implantable amplifying circuit for recording electrical signals generated by a nerve and detected by a pair of electrode wires in contact with the nerve, the amplifying circuit comprising:
- a preamplifier having a pair of inputs for receiving signals from the pair of electrode wires, the preamplifier including a differential pair of input MOSFET transistors having a low input current that serves as a first protection circuit to limit current flow through the nerve and the electrode wires, a pair of bipolar transistors and a current mirror that are driven with differential outputs of the MOSFET input transistors and producing a single-ended nerve output signal;
a common signal line adapted to connect a body ground of a patient to a common voltage of the amplifying circuit;
a second protection circuit disposed in series with the common signal line including a parallel resistor/capacitor combination to limit current flow through the nerve and the common signal line.
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Accused Products
Abstract
An implantable microvolt-level signal amplifying circuit may be used for resolving electrical signals generated by nerves in the presence of larger amplitude signals generated by muscles, the heart, or external noise sources. The circuit has a low-noise, high Common Mode Rejection Ratio (CMRR) preamplifier, followed by a cascade of stages, which provide filtering and further amplification of the neural signal. The band-pass amplifying circuit can also present high Power Supply Rejection Ratio (PSRR). The output is offset-compensated by a DC restoration stage. Nerve protection circuitry minimizes or blocks DC current flow through the input terminals in the event of semiconductor failure in the preamplifier. The circuit may be incorporated onto a common monolithic circuit with follow-up circuitry for controlling Functional Electrical Stimulation (FES) devices.
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Citations
17 Claims
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1. An implantable amplifying circuit for recording electrical signals generated by a nerve and detected by a pair of electrode wires in contact with the nerve, the amplifying circuit comprising:
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a preamplifier having a pair of inputs for receiving signals from the pair of electrode wires, the preamplifier including a differential pair of input MOSFET transistors having a low input current that serves as a first protection circuit to limit current flow through the nerve and the electrode wires, a pair of bipolar transistors and a current mirror that are driven with differential outputs of the MOSFET input transistors and producing a single-ended nerve output signal; a common signal line adapted to connect a body ground of a patient to a common voltage of the amplifying circuit; a second protection circuit disposed in series with the common signal line including a parallel resistor/capacitor combination to limit current flow through the nerve and the common signal line. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An implantable amplifying circuit for recording electrical signals generated by a nerve and detected by a pair of electrode wires in contact with the nerve, the amplifying circuit comprising:
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a preamplifier having a pair of inputs for receiving signals from the pair of electrode wires, the preamplifier including a differential pair of input MOSFET transistors having a low input current that serves as a first protection circuit to limit current flow through the nerve and the electrode wires; a common signal line adapted to connect a body ground of a patient to a common voltage of the amplifying circuit; a second protection circuit disposed in series with the common signal line including a parallel resistor/capacitor combination to limit current flow through the nerve and the common signal line; at least one amplifier stage connected to an output at the preamplifier that produces an amplified nerve output signal; a DC restoration circuit having an input connected to an output of said amplifier stage.
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12. An implantable amplifying circuit for recording electrical signals generated by a nerve and detected by a pair of electrode wires in contact with the nerve, the amplifying circuit comprising:
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a preamplifier having a pair of inputs for receiving signals from the pair of electrode wires, the preamplifier including a differential pair of input MOSFET transistors having a low input current that serves as a first protection circuit to limit current flow through the nerve and the electrode wires; a common signal line adapted to connect a body ground of a patient to a common voltage of the amplifying circuit; a second protection circuit disposed in series with the common signal line including a parallel resistor/capacitor combination to limit current flow through the nerve and the common signal line; at least one band-pass amplifier connected to an output at the preamplifier that produces an amplified nerve output signal. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification