PHYSIOLOGICAL SIGNAL AMPLIFIER WITH VOLTAGE PROTECTION AND FAST SIGNAL RECOVERY
First Claim
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1. A physiological sense amplifier configured for use in a medical device to sense a physiological electrical signal of a patient comprising:
- a high pass filter comprising a capacitor and a resistor coupled in series, wherein a voltage applied across the resistor is proportional to the physiological electrical signal;
an amplifier that amplifies an input voltage to generate an output voltage, wherein the input voltage is a function of the voltage applied to the resistor when the input voltage is less than a predetermined threshold value; and
a feedback network comprising a transistor coupled in parallel with the resistor,wherein the output voltage of the amplifier is coupled to a control terminal of the transistor to activate the transistor when the input voltage exceeds the predetermined threshold value, andwherein the transistor clamps the input voltage of the amplifier to a substantially constant value when the transistor is activated.
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Abstract
A physiological sense amplifier achieves fast recovery times following receipt of a large voltage, such as when a defibrillation pulse is delivered, without blanking. The recovery time may be less than one millisecond when polarization of surrounding tissue or the housing of the device is not present. The sense amplifier uses a feedback network to clamp the input voltage to a gain amplifier at a predetermined value when a predetermined threshold value is exceeded.
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Citations
27 Claims
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1. A physiological sense amplifier configured for use in a medical device to sense a physiological electrical signal of a patient comprising:
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a high pass filter comprising a capacitor and a resistor coupled in series, wherein a voltage applied across the resistor is proportional to the physiological electrical signal; an amplifier that amplifies an input voltage to generate an output voltage, wherein the input voltage is a function of the voltage applied to the resistor when the input voltage is less than a predetermined threshold value; and a feedback network comprising a transistor coupled in parallel with the resistor, wherein the output voltage of the amplifier is coupled to a control terminal of the transistor to activate the transistor when the input voltage exceeds the predetermined threshold value, and wherein the transistor clamps the input voltage of the amplifier to a substantially constant value when the transistor is activated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A medical device comprising:
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a sense amplifier that receives a differential voltage from first and second electrodes, outputs a voltage proportional to the differential voltage when the differential voltage is less than a predetermined threshold value, and outputs a substantially constant voltage when the differential voltage exceeds the predetermined threshold value; and a processor to process the output of the sense amplifier to sense a physiological signal of a patient, wherein the sense amplifier comprises; a high pass filter comprising a capacitor and a resistor coupled in series, wherein a voltage applied across the resistor is proportional to the physiological electrical signal; an amplifier that amplifies an input voltage to generate an output voltage, wherein the input voltage is a function of the voltage applied to the resistor when the input voltage is less than a predetermined threshold value; and a feedback network comprising a transistor coupled in parallel with the resistor, wherein the output voltage of the amplifier is coupled to a control terminal the transistor to activate the transistor when the input voltage exceeds the predetermined threshold value, and wherein the transistor clamps the input voltage of the amplifier to a substantially constant value when the transistor is activated. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A medical system comprising:
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a first medical device configured to deliver an electrical stimulation signal to a patient; a second medical device configured to sense a physiological electrical signal of the patient, the second medical device comprising; a sense amplifier that receives a differential voltage from first and second electrodes, outputs a voltage proportional to the differential voltage when the differential voltage is less than a predetermined threshold value, and outputs a substantially constant voltage when the differential voltage exceeds the predetermined threshold value, wherein the electrical stimulation signal delivered by the first medical device causes the differential voltage to exceed the predetermined threshold value; and a processor to process the output of the sense amplifier to sense a physiological signal of a patient, wherein the sense amplifier comprises; a high pass filter comprising a capacitor and a resistor coupled in series, wherein a voltage applied across the resistor is proportional to the physiological electrical signal; an amplifier that amplifies an input voltage to generate an output voltage, wherein the input voltage is a function of the voltage applied to the resistor when the input voltage is less than a predetermined threshold value; and a feedback network comprising a transistor coupled in parallel with the resistor, wherein the output voltage of the amplifier is coupled to a control terminal of the transistor to activate the transistor when the input voltage exceeds the predetermined threshold value, and wherein the transistor clamps the input voltage of the amplifier to a substantially constant value when the transistor is activated. - View Dependent Claims (24, 25, 26, 27)
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Specification