On-chip short-time interval measurement for high-speed signal timing characterization

We present in this paper an on-chip approach to obtain timing characterization for the ever faster high-speed communication systems. In the proposed short time interval measurement circuit, we use a time-to-digital converter, which consists of a charge pump, a comparator with hysteresis, a 6-bit digital counter, and a capacitor. During the measurement, we control a current source and a current sink to charge or discharge a common capacitor, and record the time length ratio of the charging and discharging process. Using this method, we can easily calculate most of the time-domain parameters. Because the measurement process is independent of the absolute value of the capacitor and current amplitude, this method minimizes the impact of the process variations.