Pacer sense amplifier
First Claim
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1. A pacer sense amplifier circuit for generating a logic level signal in response to sensed intracardiac electrograms (EKG) comprising:
- a first electrode capable of being coupled to cardiac tissue, for receiving said EKG signals;
a second electrode capable of being coupled to cardiac tissue, for receiving said EKG signals;
an anti-aliasing filter coupled to said first electrode and said second electrode for defining the frequency domain response of said sense amplifier circuit;
a sampling capacity having first and second terminals;
a first pair of switches actuated in response to a first clock pulse for coupling said sampling capacitor to said anti-aliasing filter;
a buffer amplifier for presenting a high impedance load to said sampling capacitor and presenting a low impedance source to a waveform recovery circuit;
a second pair of switches actuated in response to a second clock pulse for coupling said sampling capacitor to said buffer amplifier;
a waveform recovery circuit coupled to said buffer amplifier for smoothing the sampled waveform to reconstruct the original EKG waveform;
a bandpass/level detector coupled to said waveform recovery circuit for generating a logic level signal whenever said recovered waveform generates sufficient energy within the passband of said detector, indicative of a cardiac depolarization.
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Abstract
A pacemaker sense amplifier circuit exhibiting a very high common mode rejection ratio for detecting intracardiac electrogram signals is disclosed. The circuit includes a sampling capacitor which is differentially charged by the intracardiac signal. The voltage stored on the sampling capacitor is periodically applied to a high input impedance differential voltage amplifier which is referenced to the battery ground. The signal is smoothed and reconstructed by a bandpass filter, and is applied to a comparator to generate a logic level pulse indicative of the occurrence of a cardiac depolarization.
21 Citations
1 Claim
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1. A pacer sense amplifier circuit for generating a logic level signal in response to sensed intracardiac electrograms (EKG) comprising:
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a first electrode capable of being coupled to cardiac tissue, for receiving said EKG signals; a second electrode capable of being coupled to cardiac tissue, for receiving said EKG signals; an anti-aliasing filter coupled to said first electrode and said second electrode for defining the frequency domain response of said sense amplifier circuit; a sampling capacity having first and second terminals; a first pair of switches actuated in response to a first clock pulse for coupling said sampling capacitor to said anti-aliasing filter; a buffer amplifier for presenting a high impedance load to said sampling capacitor and presenting a low impedance source to a waveform recovery circuit; a second pair of switches actuated in response to a second clock pulse for coupling said sampling capacitor to said buffer amplifier; a waveform recovery circuit coupled to said buffer amplifier for smoothing the sampled waveform to reconstruct the original EKG waveform; a bandpass/level detector coupled to said waveform recovery circuit for generating a logic level signal whenever said recovered waveform generates sufficient energy within the passband of said detector, indicative of a cardiac depolarization.
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Specification
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Current AssigneeMedtronic Incorporated (Medtronic Plc)
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Original AssigneeMedtronic Incorporated (Medtronic Plc)
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InventorsNelson, Gary E.
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Primary Examiner(s)NOT, DEFINED
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Assistant Examiner(s)Shein, Mitchell J.
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Application NumberUS06/730,417Time in Patent Office414 DaysField of Search128/419 PG, 128/902, 128/696, 128/708, 330/109US Class Current607/9CPC Class CodesA61N 1/3704 Circuits specially adapted ...Y10S 128/902 Biological signal amplifier
