Pacer sense amplifier

Claim 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.