What is the function of a phase-locked loop (PLL) in electronics?

• A. To amplify signals for better transmission
• B. To synchronize the output signal's phase with a reference signal
• C. To convert signals from analog to digital
• D. To create a feedback loop in power systems

Answer: (B)

A phase-locked loop (PLL) is a control system that generates an output signal whose phase is related to the phase of an input or reference signal. Its primary function is to synchronize the output signal's phase with that of the reference signal. This synchronization is achieved through the use of a feedback mechanism that adjusts the output signal in response to any differences between the input signal and the output signal. This process is essential in various applications, such as in communication systems for frequency synthesis, demodulation, and in clock recovery circuits.

PLLs are fundamental in ensuring that signals remain aligned even in the presence of noise or variations in frequency. The ability to precisely maintain phase alignment makes them invaluable in scenarios where timing and synchronization are critical, such as in data transmission and radio frequency applications.