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How to connect two amplifiers used as voltage followers in parallel?

Latest Updated:10/01/2006

Question:

Is it OK to connect two operational amplifiers used as voltage followers in parallel?

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Answer:

When two operational amplifiers are connected in parallel, stable operation cannot be expected for the following reason, so such use should be avoided. If this method is used, a difference in potential may exist between output of the two voltage follower operational amplifiers due to the offset voltage (even if the input voltage to the two operational amplifiers is the same). (Different potentials between the two operational amplifiers are connected with a 0 Ω resistor.) Under these conditions, since one operational amplifier outputting higher voltage forces the voltage to rise and the other outputting lower voltage makes it fall, current flows between both outputs, and even if the input voltage changes, it is not tracked and the operation is unstable.
Suitable Products
Operational Amplifiers
USB2.0 Host/Peripheral Controller
UPD720150