Phase Frequency Detector With Minimal Blind Zone for Fast Frequency Acquisition

Blind zone in a phase-frequency detector (PFD) reduces the input detection range and aggravates cycle slips. This brief analyzes the blind zone in latch-based PFDs and proposes a technique that removes the blind zone caused by the precharge time of the internal nodes. With the proposed technique, the PFD achieves a small blind zone close to the limit imposed by process-voltage-temperature variations. The comparison between the proposed design and previous works is presented. Fabricated in a 130-nm CMOS technology, the measured blind zone is 61 ps, which is smaller than that of the existing topologies by almost 100 ps.