Compensating method for a PLL circuit that functions according to the two-point principle, and PLL circuit provided with a compensating device

摘要

A PLL circuit is tuned to a first frequency by using a first digital modulation signal and subsequently tuned to a second frequency by using a second digital modulation signal. A differential signal, that is a function of the change in voltage of a VCO control signal generated by the modulation signals, is compared with a comparison signal, that is characteristic of the analog modulation amplitude. Based on the comparison the analog modulation amplitude is changed to minimize or substantially eliminate a deviation between the signals.