Design and Analysis of a Redundant, Low-Jitter Clocking System for White Rabbit Synchronization Switches

This work presents the design and validation of a redundant, low-jitter clock architecture for White Rabbit (WR) Switches, developed to meet the growing demand for sub-nanosecond synchronization in distributed scientific and industrial systems. WR relies on two high-purity clock signals (125 MHz and 124.992 MHz) to perform picosecond-resolution phase measurements using the DDMTD method; therefore, clock quality directly determines synchronization accuracy. The proposed architecture introduces a dual-path oscillator subsystem combining two independent low-phase-noise crystal oscillators with a secondary VCXO-based synthesizer, enabling deterministic automatic failover and eliminating the PLL-based frequency-generation stage used in legacy designs. Advanced signal- and power-integrity simulations were employed to optimize impedance control, PDN performance, and crosstalk behavior across the multilayer PCB. Measurements on the prototype demonstrate a reduction in integrated jitter from approximately 300 ps in previous implementations to 35–55 ps in the primary path, while failover events exhibit a worst-case switchover time of 10 µs and a maximum phase hit below 150 ps. These results confirm that the redesigned architecture significantly enhances synchronization robustness and clock stability, providing a reliable foundation for large-scale deployments in high-energy physics, telecommunications, industrial automation, and other domains requiring ultra-precise timing.