It is meaningless to refer to a phase measurement unless it is relative to another signal or to the original phase. Repeatability, predictability, and adjustability of the phase of a signal all play an increasingly important role in modern communication and instrumentation applications.
However, with growing demand for efficiency, bandwidth, and performance, RF engineers have to devise new techniques to improve spectral and power efficiency. Until comparatively recently, little attention was paid to the behavior of phase in these circuits. While this property still has many applications, PLLs today are most commonly used in frequency synthesis, generally as local oscillators (LOs) in frequency up/downconverters, or clocks for high speed analog-to-digital converters (ADCs) or digital-to-analog converters (DACs).
Phase Alignment and Control on the ADF4356/ADF5356 DevicesĪs their name suggests, phase-locked loops (PLLs) use a phase detector to compare a feedback signal with a reference signal, locking the phases of both signals together.
