Implantable cardiac stimulator with automatic gain control.

摘要

An implantable cardiac stimulator for detecting and treating bradycardias includes a sense amplifier (25) responsive to sensed cardiac signals for detecting cardiac activity. The sense amplifier includes an automatic gain control amplifier (60), a filter (70) and quad comparator (80) having a pair of signal channels to establish sensing thresholds, margins and signal gain. The sense amplifier has a feedback loop containing a microprocessor (68) which implements preselected algorithms in conjunction with the outputs of the quad comparator to variably adjust the amplifier gain and to programmably control the sensing margin.