Investigating Phase Detectors: Advances in Mature and Emerging Phase-Frequency and Time-to-Digital Detectors in Phase-Locked Looped Systems

Detectors play an important role in many communication systems such as delay locked loops, alias-locked loops, digital-microwave radio, clock-data recovery and phase-locked loops (PLLs). A phase frequency detector (PFD) is one of the mature detector circuit designs used to detect phase and frequency differences of input signals. Time-to-digital converter (TDC) blocks are a modern and emerging technique used to quantify these phase and frequency differences precisely. This article presents the advances in mature and emerging phase-frequency and time-to-digital detectors in phase-locked loop systems.