Monolithic Phase-Locked Loop MCQ [Free PDF] - Objective Question Answer for Monolithic Phase-Locked Loop Quiz

1. What is the conversion ratio of the phase detector in 565 PLL?

A. 0.14
B. 0.35
C. 0.4458
D. 0.7

Answer: C

The conversion ratio of the phase detector of

565 PLL (Monolithic PLL) K_φ = 1.4/π = 0.4458.

2. Given f_o = 1.2kHz and V = 13v, find the lock-in range of the monolithic Phase-Locked Loop.

A. ±575Hz
B. ±720Hz
C. ±150Hz
D. ±1kHz

Answer: B

The lock-in range of monolithic PLL,

△f_L = ±(7.8×f_o)/V = ±(7.8×1.2kHz)/13 = ±720Hz.

3. A monolithic phase detector is preferred for critical applications as it is:

A. Independent of variation in amplitude
B. Independent of variation in the duty cycle of the input waveform
C. Independent of variation in response time
D. Both 1 and 2

Answer: D

Monolithic phase detectors are not sensitive to harmonics of the input signal and changes in the duty cycle of input and output frequency.

4. Determine the capture range of IC PLL 565 for a lock-in range of ± 1kHz.

A. △FC = ±31.453Hz
B. △f_c = ±66.505Hz
C. △f_c = ±87.653Hz
D. None of the mentioned

Answer: B

The capture range is

△f_c = ±[△f_L/ (2π×3.6×10³×C]^0.5

= ±[1kHz/(2π×3.6×kΩ×10µF)]^0.5

= ±[1kHz/226.08×^-6]^0.5 = [4423]^0.5 = ±66.505Hz.

5. Find the lock-in range of the monolithic Phase-Locked Loop from the given diagram.

A. -f_o-△f_L to f_o-△f_L
B. -f_o-△f_L to -f_o-△f_C
C. f_o-△f_L to f_o-△f_C
D. -f_o-△f_C to f_o-△f_C

Answer: A

Lock-in range of monolithic PLL is from -f_o-△f_L to f_o-△f_L.

6. At what range the PLL can maintain the lock in the circuit?

A. Lock in range
B. Input range
C. Feedback loop range
D. None of the mentioned

Answer: A

The change in frequency of the incoming signal can be tracked when the PLL is locked. So, the range of frequencies over which PLL maintains the lock with the incoming signal is called the lock-in range.

7. At which state the phase-locked loop tracks any change in input frequency?

A. Free running state
B. Capture state
C. Phase-locked state
D. All of the mentioned

Answer: C

In the phase-locked, the output frequency is the same as the input signal frequency. So the circuit tracks any change in the input frequency through its repetitive action.

8. Output current in general-purpose op-amp can be increased using

A. Power comparator
B. Power amplifier
C. Power resistor
D. Power booster

Answer: D

A simple method of increasing the output current of a general-purpose op-amp is to connect a power booster in series with the op-amp.

9. Which type of power transistor is chosen for a discrete power booster?

A. Collector follower stage
B. Emitter follower stage
C. Base follower stage
D. None of the mentioned

Answer: B

A discrete power booster is formed by an emitter follower stage using a power transistor. Because of unity gain, the emitter follower helps to retain the voltage gain characteristics of the general-purpose op-amp.

10. What is the power dissipation of the power transistor?

A. ≅ 0.5W
B. ≤ 0.5W
C. > 0.5W
D. ≠ 0.5W

Answer: C

Transistors with power dissipation larger than 1/2 (0.5)W are called power transistors.

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