ECE

ELECTRONIC CIRCUIT PART -3

41. Define input offset voltage?

It is defined as the voltage that must be applied between the input terminals of an op-amp to nullify the output.

42. Define input offset current?

It is defined as the algebraic difference between the current entering the inverting and non-inverting terminal of an op-amp.

43. Define input bias current?

It is defined as the average of the currents entering into the input terminals of an op-amp.

44. What are the two compensating techniques used in frequency compensation?

Two types of compensating techniques are used, they are,
a. External compensation
b. Internal compensation

45. What is compensated op-amp?

Op-amp, which uses a capacitor internally for compensation, is called a compensated op-amp. This op-amp has a high gain stability and low bandwidth.

46. What are the methods used in external compensation technique?

a. Dominant-pole compensation
b. Pole-zero compensation

47. Define slew rate?

Slew rate can be defined as the maximum rate of change of output voltage of op-amp with respect to time.

48. How can the slew rate be made faster?

The slew rate can be made faster by having a high charging current or a small capacitance value.

49. What are the methods to improve slew rate?

a. The slew rate can be improved with higher closed-loop gain and dc supply voltage. But 

the slew rate also varies with temperature. i.e., slew rate decreases with increase in temperature.
b. Another method for improving slew rate is, the rate at which voltage across the capacitor increases is gain by,dVc/dt = I / C. where, I is the maximum current furnished by the op-amp to the capacitor C. From the equation it is clear that for a higher slew rate, op-amp should have either a higher current or a small value of capacitor.

50. What are the AC characteristics of an op-amp?

a. Frequency response
b. Slew rate

51. What are the DC characteristics of an op-amp?

a. input bias current
b. Input offset current
c .Input offset voltage
d. Thermal drift

52. What is the type of feedback employed in the inverting op-amp amplifier?

Negative feedback is employed in the inverting op-amp amplifier.

53. List the applications of instrumentation amplifier.
a. Temperature indicator
 b. Temperature controller 
c. Light intensity meters 
d. Water flow meter
c. Thermal conductivity meter 
f. Analog weight scale

54. What is the basic building block of an op-amp?

The basic building block of an op-amp is differential amplifier.

55. Define non-inverting amplifier?

The input is applied to the non-inverting input terminal and the inverting terminal connected to the ground.

56. What is meant by voltage follower?

If the output voltage of an op-amp follows the input i.e., if the output voltage is equal to the input voltage it is called as a voltage follower.

57. Define Common Mode Rejection Ratio.

It is defined as the ratio of differential gain to common mode gain.it gives the figure of merit for differential amplifier

58. What is a Multivibrator?

Multivibrator is a wave shaping circuit which gives symmetric or asymmetric square wave output. It has two states. They may be either stable or quasi stable depends upon the type of the Multivibrator.

59. What is Astable Multivibrator?

Astable Multivibrator is a square wave circuit. It has two quasi stable states. It is also referred as free running Multivibrator.

60. What is a monostable Multivibrator?

A monostable Multivibrator is a square wave shaping circuit having one stable state and another quasi stable state. It is often referred as single shot Multivibrator. It is also used as gating circuit and delay circuit.

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