A hybrid amplifier for electrophysiological signal recording

A portable analog signal processing unit suitable for ambulatory electrophysiological signal recording is described. The system includes miniature preamplifiers mounted 2cm from the recording electrodes and a multichannel post-amplifier unit. The preamplifier consists of an instrumentation amplifier with a gain of 100 and single pole high pass and low pass filters. Each channel of the post-amplifier module consists of an isolation amplifier, variable gain amplifier, low and high pass switched capacitor filters and a driving amplifier. This module provides additional gain, optical isolation, and antialiasing. With this new system environmental and biological recording artifacts are significantly reduced and high signal to noise ration is achieved.