Electrical Engineering ⇒ Topic : Ideal operational amplifier

THE IDEAL OPERATIONAL AMPLIFIER

An operational amplifier is called ideal if the following characteristics are satisfied:

• Infinite voltage gain
• Zero output impedance

This type of OP Amp is also called a voltage controlled voltage source (VCVS). Ideal OP Amps can be used to perform a large number of mathematical operations. It can also generate a number of circuit functions by applying passive feedback around the amplifier. The symbol of OP Amp is shown in Figure (a).

                                               figure (a)  Ideal operational amplifier

The ideal operational amplifiers have the following characteristics:

• The voltage gain A_v → ∞. The output voltage V₀, is finite.
• R_i  → ∞  (open-circuited). Therefore, no current enters the input terminals and I₁ = I₂ = O.
• R₀ = O.
• When V₁ = V₂, V_O, = O. This indicates zero offset.
• The bandwidth is infinite. So the amplifiers give response equally at all frequencies.