THE IDEAL OPERATIONAL AMPLIFIER

Although the characteristics of an ideal operational amplifier are unattainable, modern integrated circuit types can provide an extremely close approximation.

The ideal characteristics are:

* A very large open loop gain, near infinite,

* Output unaffected by signal frequency, no signal phase shift with change in frequency,

* A very large (infinite) input impedance so that the amplifier takes negligible current,

* A very small output impedance so that the output of the amplifier is unaffected by loading,

* Output voltage is zero for zero input voltage (offset zero applied).

Naturally, no practical operational amplifier will be this perfect, which means of course that there will be small operational errors with such devices. Therefore, the closer to the ideal properties the amplifier is made, the smaller will be these errors.