Calibrating Fiber Propagation Delay Asymmetry and Switch Queue Noise in PTP Boundary Clock Topologies
Precision time accuracy demands fixed optical wavelength asymmetry offsets and sub-nanosecond egress timestamping at each boundary clock.
Loop Bandwidth
Meaning
Frequency range over which a phase-locked loop can track and respond to variations in the phase of the input signal defines the primary operational limit of a synchronization system. In electronic oscillators and clock recovery units, loop bandwidth determines both the speed of lock acquisition and the degree of high-frequency noise filtering. Designing this parameter involves a fundamental trade-off between the rapid tracking of input phase changes and the rejection of phase noise from the reference clock.
Tracking Capability
A narrow filter response limits the ability of the system to follow sudden phase changes in the input signal. This constraint reduces the tracking capability of the circuit when the reference frequency exhibits rapid wander or jitter.
Noise Rejection
A wider control band allows the system to lock onto the reference clock quickly and hold the lock under dynamic conditions. However, this wider response allows high-frequency noise from the input signal to pass through to the output oscillator, raising the jitter of the system. In contrast, limiting the band limits the jitter transfer from the input but increases the time required to achieve initial lock during startup or recovery.
Circuit Stability
Determining the optimal damping factor and frequency response ensures the circuit does not oscillate or become unstable under transient conditions. This stability preserves the long-term integrity of the clock distribution network.