Measuring clock jitter at 100 GHz from PM noise measurements

"Jitter" is the noise modulation due to random time shifts on an otherwise ideal, or perfectly on-time, signal transition. This paper presents ways of calculating timing jitter using phase-modulation (PM) and amplitude-modulation (AM) noise measurements of high-speed digital clocks. A 100 GHz case is used for illustration and based on actual measurements. In the absence of ultra-high speed jitter analyzers, spectrum analysis is an alternate noise measurement for timing jitter. A summary table is provided for mapping the results of these measurements in the Fourier frequency domain to jitter in the /spl tau/ domain for various random (specifically, power-law) noise types, spurs, vibration, and power-supply ripple. In general, one cannot unambiguously map back, that is, translate from jitter measurements to phase noise. Measurements of phase noise are typically much more sensitive to phase (or time) fluctuations than a jitter analyzer.