An operational amplifier (op-amp) is an integrated direct-coupled differential voltage amplifier characterized by extremely high open-loop voltage gain, high input impedance, and low output impedance. In negative feedback configurations, the immense open-loop gain drives the differential input voltage to near zero (virtual ground condition V_+ ≈ V_-). As a consequence, the closed-loop transfer function is determined solely by external precision passive components rather than open-loop silicon parameters.