Active deskew in injection-locked clocking

This paper presents an injection-locked clock (ILC) distribution system with a new active deskew mechanism based on the built-in phase tuning of injection-locked oscillators (ILO). The proposed technique removes the required deskew delay lines and associated power dissipation, clock latency and jitter accumulation in conventional active deskew schemes. A test chip was fabricated in a standard 0.18 mum digital CMOS process to demonstrate this new technique. Working at 3.5 GHz clock frequency, the ILOs in the ILC achieved 40 ps deskew range with a step size of 1.25 ps. The deskew loop successfully achieved a skew reduction from the preset value of 16 ps to 2 ps. The cycle-to-cycle jitter degradation from clock input to clock output is measured only 0.04 ps.