Low power A/D converter
First Claim
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1. A method of cardiac signal analysis comprising:
- capturing an electrical signal between implanted electrodes;
receiving the electrical signal on a first chip carrying substantially all analog components of a subcutaneous implantable cardioverter defibrillator (SICD);
sampling the electrical signal to create a first sample and storing the first sample on the first chip;
generating an output from the first chip by comparing the first sample to a stored sample also stored on the first chip using a comparator located on the first chip;
receiving the output from the first chip on a second chip carrying substantially all digital components of the SICD;
generating a digital signal on the second chip indicative of the amplitude of the captured electrical signal; and
wherein the output from the first chip is the output from the comparator.
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Abstract
A comparator is arranged to compare a series of analog voltage signal samples on a first capacitor with a voltage on a second capacitor which is linearly increased or decreased to equal the sample value. The comparator'"'"'s single output freezes the count of the counter at counts which are proportional to the voltage of the respective samples. In this manner, analog to digital conversion can be accomplished using a single line between the analog and digital sides of a circuit, thereby reducing parasitic capacitance.
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Citations
13 Claims
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1. A method of cardiac signal analysis comprising:
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capturing an electrical signal between implanted electrodes; receiving the electrical signal on a first chip carrying substantially all analog components of a subcutaneous implantable cardioverter defibrillator (SICD); sampling the electrical signal to create a first sample and storing the first sample on the first chip; generating an output from the first chip by comparing the first sample to a stored sample also stored on the first chip using a comparator located on the first chip; receiving the output from the first chip on a second chip carrying substantially all digital components of the SICD; generating a digital signal on the second chip indicative of the amplitude of the captured electrical signal; and wherein the output from the first chip is the output from the comparator. - View Dependent Claims (2, 3, 4, 5)
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6. An implantable medical device comprising at least first and second implantable electrodes and operational circuitry including a first chip carrying substantially all analog components of a subcutaneous implantable cardioverter defibrillator (SICD) and a second chip carrying substantially all digital components of the SICD, the operational circuitry configured to perform cardiac signal analysis comprising:
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capturing an electrical signal between the implantable electrodes; receiving the electrical signal on the first chip; sampling the electrical signal to create a first sample and storing the first sample on the first chip; generating an output from the first chip by comparing the first sample to a stored sample also stored on the first chip using a comparator located on the first chip; receiving the output from the first chip on the second chip; generating a digital signal on the second chip indicative of the amplitude of the captured electrical signal; and wherein the operational circuitry is configured such that the output from the first chip is the output from the comparator. - View Dependent Claims (7, 8, 9, 10)
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11. A method of cardiac signal analysis comprising:
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capturing a cardiac signal from electrodes implanted in a patient; sampling a first sample related to a magnitude of the captured signal; generating an output having a duration and a sign, the duration indicative of a magnitude of difference between the first sample and a previous sample and the sign indicative of a direction of difference between the first sample and a previous sample; receiving the output at a counter and generating a digital output indicative of the magnitude of the first sample; wherein the output is generated from analog circuitry on a first chip carrying substantially all analog components of a subcutaneous implantable cardioverter defibrillator (SICD) and the counter is disposed on a second chip carrying substantially all digital components of the SICD, the method further comprising conveying the output from the first chip to the second chip; the output generated from the analog circuitry on the first chip is the output from a comparator. - View Dependent Claims (12, 13)
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Specification