Define PLL capture range and lock range.
1 Answer
In the context of a Phase-Locked Loop (PLL), the terms "capture range" and "lock range" refer to specific operational regions that describe the behavior of the PLL as it acquires and maintains synchronization with an input signal. A PLL is a control system commonly used to synchronize the phase and frequency of an output signal with those of a reference input signal. Let's define these terms:
Capture Range:
The capture range of a PLL is the range of input frequencies over which the PLL can acquire and synchronize with the input signal. It is the span of frequencies within which the PLL's internal control loop is capable of aligning the phase and frequency of the output signal with the reference input signal. The capture range is often defined by the frequency difference between the input signal and the VCO (Voltage-Controlled Oscillator) frequency when the PLL begins its acquisition process. If the input frequency is within the capture range, the PLL will be able to lock onto and track the input signal's frequency and phase.
Lock Range:
The lock range of a PLL is the range of input frequencies over which the PLL can maintain synchronization and stay locked to the input signal. Once the PLL has captured the input signal and achieved synchronization, it can continue to operate within the lock range without losing lock. The lock range is determined by the bandwidth and characteristics of the PLL's control loop. If the input frequency deviates beyond the lock range, the PLL may lose synchronization, and its output signal might deviate from the desired phase and frequency alignment.
In summary, the capture range defines the frequency span over which a PLL can acquire synchronization with an input signal, while the lock range defines the frequency span over which the PLL can maintain synchronization once it has acquired lock. These ranges are essential parameters in the design and analysis of Phase-Locked Loops, particularly in applications where maintaining precise phase and frequency alignment is critical.
Capture Range:
The capture range of a PLL is the range of input frequencies over which the PLL can acquire and synchronize with the input signal. It is the span of frequencies within which the PLL's internal control loop is capable of aligning the phase and frequency of the output signal with the reference input signal. The capture range is often defined by the frequency difference between the input signal and the VCO (Voltage-Controlled Oscillator) frequency when the PLL begins its acquisition process. If the input frequency is within the capture range, the PLL will be able to lock onto and track the input signal's frequency and phase.
Lock Range:
The lock range of a PLL is the range of input frequencies over which the PLL can maintain synchronization and stay locked to the input signal. Once the PLL has captured the input signal and achieved synchronization, it can continue to operate within the lock range without losing lock. The lock range is determined by the bandwidth and characteristics of the PLL's control loop. If the input frequency deviates beyond the lock range, the PLL may lose synchronization, and its output signal might deviate from the desired phase and frequency alignment.
In summary, the capture range defines the frequency span over which a PLL can acquire synchronization with an input signal, while the lock range defines the frequency span over which the PLL can maintain synchronization once it has acquired lock. These ranges are essential parameters in the design and analysis of Phase-Locked Loops, particularly in applications where maintaining precise phase and frequency alignment is critical.