(A) The BIS XP Digital Signal Converter (DSC), which converts between the analog EEG signals measured from the patient’s forehead and a digital transmission stream to the main device. The DSC also provides electrical isolation between the patient and the device.
(B) The DSC internal circuitry, which is constructed in a clamshell fashion with two circuit boards facing each other with three interconnection points between them. When assembled, this circuitry is wrapped in a flexible, conductive sheet which serves as a ground plane to block electrical interference. This sheet is removed in this image for visibility.
(C) Opening the clamshell reveals that the circuitry is divided into a device side comprised primarily of digital circuitry, and a patient side comprised primarily of analog circuitry. Precision amplifiers are notable on the analog patient side for capturing EEG signals.