ECE-105 Chapter Notes - Chapter 14: Kirchhoff'S Circuit Laws, Phasor, Cutoff Frequency
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The operational amplifier is a differential amplifier having both inverting and noninverting input terminals: the input signals are denoted as, the input signal of a differential amplifier consists of a differential component and a common-mode component. The average of the input voltages or the common-mode signal is expressed as: The difference between the input voltages or the differential signal is. An ideal operational amplifier has the following characteristics: expressed as: Infinite gain for the differential input signal: zero gain for the common-mode input signal, zero output impedance. Op amps are generally used with feedback networks that return part of the output signal to the input. Thus, a loop is created in which signals flow through the amplifier to the output and back through the feedback network to the input. The open-loop gain is the gain of the op amp without a feedback network expressed as:
