INSTRUMENTATION OPERATIONAL AMPLIFIER Russian patent published in 1996 - IPC

FIELD: precision- measurement operational amplifiers for radio engineering and medical instruments (electrocardiographs, electroencephalographs, electromyographs). SUBSTANCE: amplifier has first, second, and third operational amplifiers. Noninverting inputs of first and second operational amplifiers functions as inputs of instrumentation operational amplifier. Inverting input and output of first operational amplifier are connected through first resistor to inverting input and output of second operational amplifier. Power leads of first and second current mirrors are connected, respectively, to positive and negative voltage buses. Input of second current mirror is connected to negative power lead of second operational amplifier; positive power lead of second operational amplifier is connected to positive voltage bus. Output of third operational amplifier functions as output of instrumentation operational amplifier. Variable resistor is inserted between negative voltage bus and output of first current mirror; output of second current mirror is connected to input of first current mirror, inverting input of third operational amplifier and, through second resistor, to output of third operational amplifier whose noninverting input is connected to ground. Negative power lead of first operational amplifier is connected to input of second current mirror; positive power lead of first operational amplifier is connected to positive voltage bus. EFFECT: reduced nonlinear distortions of amplified signals. 1 dwg