HELP 21

Question

Answer 1

(5.2)

Internal gain of the operational amplifier is the open loop gain of the amplifier.

This gain can be controlled or changed by providing feedback in the amplifier.

Advantages of feedback :

     1) Circuit characteristics such as the systems gain and response can be precisely controlled.

     2) Circuit characteristics can be made independent of operating conditions such as supply voltages or temperature variations.

     3) Signal distortion due to the non-linear nature of the components used can be greatly reduced.

     4) The frequency response, gain and bandwidth of a circuit or system can be easily controlled to within tight limits.

Answer 2

(5.4)

Step 1:

Input voltage of operational amplifier is .

Feedback resistance is .

Input resistance is .

Since the output voltage is 180° out of phase with the input voltage, the op-amp acts as an inverting amplifier.

Gain of an inverting amplifier is

Substitute corresponding values in above formula.

Voltage gain of the amplifier is .

Step 2:

Expression for input voltage of non inverting amplifier is

Substitute corresponding values in above formula.

Expected output voltage is  V.

Note : Negative sign indicates that the output voltage is 180° out of phase with the input voltage.

Solution :

Voltage gain of the amplifier is .

Expected output voltage is V.