Instrumentation amp and DRL PUBLIC

Instrumentation amplifier and driven-right-leg feedback circuit for biosignal recording.

Simulation of an instrumentation amplifier measuring a biosignal (simulated as a 200 Hz differential voltage) with an underlying common-mode signal due to capacitive coupling from the mains (at 50 Hz). Voltage divider effect is simulated by mismatching the electrode lead resistances, albeit with exaggerated large lead capacitances (at 5 nF). The instrumentation amplifier is balanced and so CMRR is ideal (infinite). A switch is put in to disconnect the driven-right-leg (DRL) feedback circuit if desired.