AMPLIFIERS FOR BIOELECTRIC EVENTS - A DESIGN WITH A MINIMAL NUMBER OFPARTS

A design for an amplifier for bioelectric events is presented that has fewer parts than conventional designs. The design allows the construc tion of amplifiers of a high quality in terms of noise and common mode rejection, with reduced dimensions and with a lower power consumption . Gain, bandwidth and number of channels are easily adapted to a wide range of biomedical applications. An application example is given in t he form of a multichannel EEG amplifier (gain is 20 000), in which eac h channel consists of three operational amplifiers (one single and one dual), six resistors and two capacitors. The equivalent input noise v oltage and current are 0.15 mu V-rms and 1 pA(rms), respectively, in a bandwidth of 0.2-40 Hz, and a common mode rejection ratio of 136 dB i s achieved without trimming.