A 10 Bit Phase-Interpolator-Based Digital-to-Phase Converter for Accurate Time Synchronization in Ethernet Applications

This work presents a 10 Bit digital-to-phase converter (DPC), for usage within an accurate time synchronization via Ethernet with a nominal frequency of 125 MHz. It is based on a 16-phase ring oscillator, stabilized by a phase-locked loop (PLL), followed by a 6 Bit phase-interpolator (PI). The DPC generates 1024 clock phases with a nominal resolution of 0.35°, covering a full 360° phase span. A prototype of the DPC is fabricated in a 180 nm technology from TSMC and achieves a differential and integral nonlinearity (DNL and INL) of 0.47° and 2.33^o, respectively, while the power consumption is only 4.0 mW. As the DPC is based on a built-in PLL, it requires only a low frequency reference clock, which makes it very well suited for easy integration in complex systems (e.g. time synchronization via Ethernet transceivers).