Thursday, November 22, 2012
Clock Skew and jitter in digital
Jitter is nothing but the displacement of signal from its original position.This movement may lag or lead from its original or ideal position.As a speed increases, the edge deviation cause a significant problems like signal integrity,skew,race condition and other timing problems.
1. cycle-to-cycle jitter
Cycle-to-cycle jitter is the change in an output’s transition in time in relation to the transition during the previous cycle.
Period jitter is the maximum change in a signal transition from the ideal position in time. Phase jitter, also called long-term jitter, in the maximum change in an output signal transition from its ideal position over many cycles (typically 10 to 20 microseconds).
3.phase jitterPhase jitter may leads to the displacement of phase from one signal to another.
Skew deals with the propagation delay of the output signal.It is the variation of propagation delay differences between output signals.Excessive skew, especially for clock signals, can cause race conditions and other timing errors that result in system data faults. At the very least, poor skew will force a slower maximum system speed, and this, in turn, will limit system performance.
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