Spread Glass Fabric Selection and Skew Mitigation in Printed Board Manufacturing
Selecting mechanically spread glass fabric and enforcing multi-ply laminate construction mitigates intra-pair differential skew without panel rotation costs.
Jitter Budget
Tolerance Distribution
High-speed channel constraints during the design phase allocate the maximum allowable time-domain variation of signal transitions among the various parts of a communication link. The compile of a jitter budget ensures that the combined timing errors of the transmitter, the transmission lines on the board and the receiver do not exceed the sampling window of the system. This allocation acts as a design guide for circuit board layout and component selection.
It applies to synchronous and asynchronous serial links, but becomes irrelevant if the transmission speed is low enough that the data period is much larger than any possible timing variation.
Component Allocation
Noise sources such as crosstalk, power supply ripple and inter-symbol interference contribute to the total timing deviation of the signal edges. Design teams calculate the individual contributions of these sources using both deterministic and random models. This step guarantees that the total combined timing error is well understood.
Verification Process
Channel simulations model the transmission path to verify that the jitter remains within the specified boundaries. If the simulation results exceed the limit, the layout must be adjusted to shorten traces or reduce crosstalk. The finalized budget is used as a baseline for physical measurements during the hardware validation phase.