30.7 An 8b Injection-Locked Phase Rotator with Dynamic Multiphase Injection for 28/56/112Gb/s Serdes Application

Growing traffic in data centers imposes multiple challenges on serial link design with higher speed and stringent power requirements. Clocking is one major challenge due to the significant portion of total power that clock distribution consumes in a serial link. Recent publications [1-4] deploy either a delay-locked loop (DLL), or an Injection-locked ring oscillator (ILRO) combined with phase interpolators (PIs) to generate multiphase clocks. For example, a 28Gb/s quarter-rate NRZ receiver requires an 8-phase 7GHz clock while a 56/112Gb/s DSP-based PAM-4 receiver requires a 4/8-phase 7GHz clock. In this work, the proposed injection-locked phase rotator (ILPR) can provide multiphase clocks without multiple PIs or a multiphase input clock.