Microjitter

Microjitter is a term used in electronics and communications to describe small, rapid variations in the timing of a signal or event within a clock domain or data stream. It refers to short‑scale timing deviations, typically in the nanosecond to microsecond range, that can occur even when the overall average timing is stable. Microjitter is often considered a component of broader jitter phenomena and is especially relevant in high-speed digital interfaces and precision timing applications.

Measurement and characterization of microjitter rely on metrics such as peak‑to‑peak and RMS jitter, as well as short‑term measures like time deviation (TDEV) over small observation windows. In clock and data recovery contexts, microjitter is assessed at the input or output of serializers, deserializers, phase-locked loops, and clock distribution networks. High‑speed links and synchronous systems are particularly sensitive to microjitter, since brief timing fluctuations can translate into bit errors or sampling instabilities.

Common sources of microjitter include instability in reference clocks, power supply noise, crosstalk, thermal fluctuations, switching noise in nearby circuitry, and data‑dependent effects from encoding schemes. In digital systems, phase noise from voltage‑controlled oscillators can contribute to microjitter, as can imperfect clock distribution and PCB layout issues.

Mitigation strategies focus on improving clock purity and signal integrity. This can involve using higher‑quality oscillators, jitter attenuators, careful power regulation, shielding and layout optimization, and robust clock/data recovery techniques. In networking and multimedia, jitter buffers and appropriate QoS measures help absorb residual microjitter to preserve quality of service.