Analog Electronic Circuits Laboratory Viva Questions 6

Theory_Questions:

1. If the emitter bias current increased in a differential amplifier then

1. Input impedance increases 2. CMRR increases 3. The gain of the circuit will increase

Which of the above statements are true

A) 1,2,3

B) 1,2

C) 2,3

D) 1 only

Answer: [C] 2,3

2. Which of the following is not the characterstic of the first stage of the op-amp

A) High CMRR

B) High common mode voltage swing

C) High input impedance

D) High gain

Answer: [D] High gain

3. In a diffrentail amplifier, given IE01 = 1μA, IE02 = 1/ e μA ( e is base of natural logarithm). The input offset voltage required to compensate the mismatch is

A) 0V

B) 1.5 mV

C) 1mV

D) Data insufficient

Answer: [D] Data insufficient

4.

p) VCVS 1. y parameter i) Voltage amplifier

q) CCCS 2. z parameter ii) Current amplifier

r) CCVS 3. h parameter iii) transresistance amplifier

s) VCCS 4. g parameter iV) transconductance amplifier

which of the following is not matched correctly

A) p - 4 – i

B) r - 2 – iii

C) s - 1- iV

D) p – 3 – ii

E) none of the above

F) All of the above

Answer: [D] p – 3 – ii

5.

P) Z and y feedbacks should be applied only with even number of stages

Q) Differential amplifier is only possible in integrated circuits

R) In the regard of handling number of stages, MOSFET current mirror is better

han BJT current mirror.

Which of the above statements are false?

A) P,Q,R

B) P only

C) Q only

D) P,Q

Answer: [B] P only

6. If the Non-inverting op-amp input is internally open, and it results in

(A) Amplifier acts as a voltage follower

(B) The op-amp is operating in open-loop

(C) The op-amp is operating in closed-loop

(D) Both (A) and (C)

(E) No signal output

(F) None of the above

Answer: [E] No signal output

7. Positive feedback occurs when

(A) The output signal is feedback to the input in-phase with the input signal

(B) The output signal is feedback to the input in-phase with the input signal

(C) The total phase shift through op-amp and feedback is 360◦

(D) Both (A) and (C)

Answer: [D] Both (A) and (C)

8. for a closed-loop op-amp circuit to be unstable

(A) There must be positive feedback

(B) The loop gain must be greater than 1

(C) The loop gain must be less than 1

(D) Both (A) and (B)

Answer: [D] Both (A) and (B)

9. Class C amplifiers are almost always

(A) Transformer coupled between the stages

(B) Operated at audio frequencies

(C) Tuned RF amplifiers

(D) Wideband

Answer: [C] Tuned RF amplifiers

10. Transistor dissipation in a class C amplifier decreases when the

(A) Resonant frequency increases

(B) Coil Q increases

(C) Load resistance decreases

(D) Capacitance increases

Answer: [B] Coil Q increases