Explanation: Before the input is applied, the PLL is in a free running state. Once the input frequency is applied, the VCO frequency start to change & PLL is said to be in capture mode. When the VCO frequency continues to change until it is equal to the input frequency, the PLL is said to be in phase locked state. 5. What is the function of low pass filter in phase-locked loop?
A. Improves low frequency noise
B. Removes high frequency noise
C. Tracks the voltage changes
D. Changes the input frequency
Answer:A
Explanation: Before the input is applied, the PLL is in a free running state. Once the input frequency is applied, the VCO frequency start to change & PLL is said to be in capture mode. When the VCO frequency continues to change until it is equal to the input frequency, the PLL is said to be in phase locked state. 5. What is the function of low pass filter in phase-locked loop?
A. Improves low frequency noise B. Removes high frequency noise C. Tracks the voltage changes D. Changes the input frequency
Explanation: The output voltage of a phase detector is a dc voltage and is often referred to as error voltage. This output is applied to the low pass filter which removes the high frequency noise and produces a dc level. 6. What is the need to generate corrective control voltage?