= Virtual ground
A circuit node held close to zero <electric potential> by active feedback, without being directly connected to the reference conductor. In an ideal linear <operational amplifier> with its non-inverting input grounded and stable negative feedback, $V_-=V_+=0$ while neither input draws <electric current>. External branch currents meeting the inverting node therefore obey <Kirchhoff's current law> without flowing into the amplifier input. Equality of the input potentials fails when the output saturates or the feedback ceases to enforce linear operation.
Back to article page
