= Ideal operational amplifier
An <ideal operational amplifier> has infinite <open-loop gain> and <input impedance>, zero <output impedance>, unlimited response speed and zero <input offset voltage> and <input bias current>. Its input currents vanish. In a stable linear circuit with <negative feedback> and a finite output, its differential input voltage tends to zero as the <open-loop gain> tends to infinity. Thus $i_+=i_-=0$ and $v_+=v_-$ are the familiar conditional circuit rules. The equality of the input voltages cannot be imposed on an open-loop, unstable or saturated circuit.
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