VERFAHREN UND EINRICHTUNG ZUR EINSPEISUNG DER VERRIEGELUNG VON SPANNUNGSGESTEUERTEN OSZILLATOREN MIT DIREKTER DIGITALER ABSTIMMUNG

摘要

The invention relates to the field of electronics and more particularly to the tuning and injection locking of voltage controlled oscillators (VCOs). An improved injection locking circuit is provided which allows the VCO to injection lock with a smaller reference signal and therefore a smaller locking bandwidth (LBW). In order to allow the VCO to injection lock with a lower power reference signal, this invention includes a pre-tuning algorithm to place the VCO frequency such that the desired frequency is in the LBW. Tuning of the VCO is achieved using direct digital tuning that does not require an input reference. Injection locking is performed using a low frequency clock harmonic as the reference signal. More specifically, tuning is accomplished by sub-sampling and digitizing the output signal of the VCO, determining the center frequency, and adjusting the VCO control voltage.