DefinePK

Abstract

Integrated instrumentation amplifiers (INA) are more expensive than discreet op-amps and cost could be a concern for multi-channel biosignal acquisition application. Instrumentation amplifiers can be developed with op-amps at a lower cost. However this approach, although cost effective, is rarely adopted. In this experiment, an EMG amplifier consisting of a preamplifier and filter stage was developed with discreet op-amps (JRC4558) and low tolerance components. Actual fabrication and testing with muscle contraction was performed, and the output was compared with a circuit built with an INA. In general, the low cost variant achieve a CMRR lower than a circuit developed with the INA, however, in practice their noise performance is comparable. The filter specification is also unaffected by the component tolerance.