REKLAB manual (EMG - preamplifiers M.M. & L.P. )
Preamplifier Module
Recorded EMGS are usually in the 0.1 to 1 mV range. They are amplified using a custom-made 3-stage differential preamplifier. The first stage is an instrumentation amplifier (Analog Devices AD625; Analog Devices, Norwood, MA) with user-selectable gains of 10 and 100. The moderate gains prevent saturation due to large common mode signals. The second stage is a single pole RC filter with a cutoff frequency of 1 Hz. The high pass filter removes low frequency artifacts due to electrode polarization and motion artifacts from the cables and electrodes. The third stage is an isolation amplifier (AD210 with a gain of 101). The overall amplifier gain can be chosen (by means of a switch on the preamplifier module) at about 1,000V/V or 10,000V/V. The amplified signals are filtered and rectified using a rectifier module.
PREAMP(AD625)
