Question

What are the desired characteristics or values for the following parameters of an ideal amplifier?o Phase change as a function of the log of the frequency o Common Mode Rejection Ratioo Input Resistanceo Output Resistance

Answer 1

Answer and Explanation:

- Phase change as a function of the log of the frequency

The phase shift should be independent of the frequency of the input signal. It should have an Infinite bandwidth with zero phase shift

- Common Mode Rejection Ratio

An ideal amplifier has Infinite common-mode rejection ratio (CMRR). A perfect operational amplifier amplifies only the voltage difference between its two inputs, completely rejecting all voltages that are common to both.

- Input Resistance

Infinite input impedance and so, zero input current & Zero input offset voltage.

The differential input impedance of the operational amplifier is defined as the impedance between its two inputs; the common-mode input impedance is the impedance from each input to ground.

And the impedance between its inputs should be infinite.

- Output Resistance

Zero output impedance and Infinite output voltage range.

Output Resistance leads to voltage drop. Thee voltage drop across the output impedance effectively reduces the open loop gain. So, the optimal value for this should be zero.

N.B - For AC circuits such as this one being discussed, resistance is known as impedance.