For a system to work, as oscillator the total phase shift of the loop gain must

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Question
For a system to work, as oscillator the total phase shift of the loop gain must be equal to
Options
A. 90�
B. 45�
C. 270�
D. 360�

Correct Answer

360�

Explanation

Gain of system with + ve feedback =

For a system to work, as oscillator the total phase shift of the loop gain must be equal to 90� 45�

for oscillation

but V₀ ? 0

so, that 1 - AB = 0 ⟹ AB = 1 ?0� or 360�.

Analog Electronics problems

Search Results

1. If the input to the ideal comparator shown in the figure is a sinusoidal signal of 8 V (peak to peak) without any DC component, then the output of the comparator has a duty cycle of
Options
A. 1/2
B. 1/3
C. 1/6
D. 1/12

2. The transistor of following figure in Si diode with a base current of 40 ?A and I_CBO = 0, if V_BB = 6V, R_E = 2 k? and ? = 90, I_BQ = 20 ?A then R_B =
Options
A. 200 k?
B. 265 k?
C. 150 k?
D. 100 k?

3. The efficiency of a full wave rectifier using centre tapped transformer is twice that in full wave bridge rectifier.
Options
A. True
B. False

4. A half wave diode rectifier has a capacitance input filter. If input voltage is V_m sin ?t, PIV is
Options
A. V_m
B. 2 V_m
C. 3 V_m
D. 4 V_m

6. The input impedance of op-amp circuit of figure is
Options
A. 120 k ohm
B. 110 k ohm
C. infinity
D. 10 k ohm

7. An RC coupled amplifier has an open loop gain of 200 and a lower cutoff frequency of 50 Hz. If negative feedback with ? = 0.1 is used, the lower cut off frequency will be
Options
A. about 50 Hz
B. about 5 Hz
C. about 2.38 Hz
D. about 70.5 Hz

8. For a base current of 10 ?A, what is the value of collector current in common emitter if ?_dc = 100
Options
A. 10 ?A
B. 100 ?A
C. 1 mA
D. 10 mA

9. Assertion (A): CE amplifier is the most widely used BJT amplifier
Reason (R): CE amplifier has zero phase difference between input and output
Options
A. Both A and R are correct and R is correct explanation for A
B. Both A and R are correct but R is not correct explanation for A
C. A is correct R is wrong
D. A is wrong R is correct

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