An improved fast acquisition PFD with zero blind zone for the PLL application

An improved fast acquisition phase-frequency detector (PFD) for Phase-Locked Loop (PLL) is presented. The proposed PFD completely eliminates the blind zone, which is caused by the missing input edge during reset pulse. It has a linear output range and a saturated output when the phase error is in [0, π] and [π, 2π]. The simulation results with the SMIC 65nm CMOS technology file show that, comparing with the published works, the proposed nonlinear gain PFD has a faster lock process, and improves the maximum operating frequency to as higher as 1GHz.