Timing Noise Characterization of High-Speed Digital Bit Sequences Using Incoherent Subsampling and Algorithmic Clock Recovery

Abstract

In this paper, we exploit a software-based nonreal-time signal acquisition technique to enable high-precision jitter characterization of multi-Gb/s pseudorandom bit sequences (PRBSs) with minimal hardware support. For signal acquisition, incoherent subsampling is employed to increase the effective sampling rate of a digitizer and to simplify its signal acquisition architecture by removing the need for timing synchronization circuits. As a substitute for hardware synchronization circuits, the multiple stages of discrete frequency estimation algorithm, called algorithmic clock recovery (CR), are used. Using the frequency estimate obtained from the proposed algorithmic CR allows us to digitally reconstruct an incoherently subsampled PRBS into a single period of the signal in the discrete-time-domain. The proposed algorithmic CR is accurate and robust, especially in the presence of signal noise and multiple aliased distortions as compared with previously published approaches. In addition, the proposed all-digital jitter characterization technique (including self-reference signal extraction) enables data-dependent jitter separation without using the tail-fitting of a jitter histogram.