Service manual

ECG Front End
3-12
Opto-Isolators
Opto-Isolators pass the digital sample data from the patient-connected circuitry to the rest
of the instrument, providing electrical isolation.
Integrated Front End Circuits/Oscillator
The Integrated Front End Circuits sample the patient leads at 4.096M samples per second
per lead. The data are then filtered to 12 bits at 5 µV/LSB and 2 msec per sample. The
circuits include protection circuitry, gain, A/D conversion, and Oscillator control. These
circuits have a master/slave arrangement, with the master driving the Oscillator and
communicating all data to the System Gate Array through the opto-isolators.
Calibration
This circuitry is used to set ECG gain for the Integrated Front End Circuits.
Defibrillator Protection
Defibrillation Protection is provided by resistors in the patient cable combined with
circuitry in the Integrated Front End Circuits.