An enhanced high-precision and time-saving jitter transfer measurement

As data rates increase and jitter margins decrease, the need to precisely attain the performance of a PLL block becomes increasingly important. A PLL block´s performance is reflected by its jitter transfer function, which is the ratio of output jitter to input jitter. A precise jitter transfer function requires a considerably large number of measurement points for the jitter transfer plot. The trade-off is an increase in measurement time. This paper presents a time-saving and cost effective jitter transfer measurement methodology that produces a precise jitter transfer function. This methodology extracts jitter transfer from the PLL output clock signal´s power spectrum variation. The power spectrum varies according to controlled noise injected into the PLL input clock signal. Jitter transfer experimental data show significant increase in precision and reduction in measurement time compared to the conventional methodology. This new methodology enables efficient characterization of PLL block behaviour across different loop parameters and consequently, improves time-to-market of a new device or electronic system introduction.