Fast frequency acquisition phase-frequency detector with zero blind zone in PLL

A simple phase-frequency detector (PFD) is described. This circuit only has 16 transistors. This PFD has linear range when the phase difference is in [0, pi], and saturates when the phase difference is in [pi, 2pi]. It completely eliminates the blind zone, speeds up the acquisition process and improves the maximum operating frequency of the PFD. Both simulation and post-simulation with HSPICE confirm these advantages.