Patent ID: 7760042

Claim:
A frequency modulator, comprising: a tuning circuit configured to determine a nominal gain characteristic of a digitally controlled oscillator (DCO) in an first mode by ascertaining an oscillator output frequency solely at two different oscillator control inputs operating points, wherein a first operating point is near a maximum end of a tuning range of the DCO and a second operating point is near a minimum end of the tuning range of the DCO, and calculating the nominal gain characteristic therefrom, and determine an actual gain characteristic of the DCO in a second mode using the nominal gain characteristic; and a modulation circuit comprising the DCO coupled to the tuning circuit, configured to modulate a frequency of a DCO output signal from the DCO with a modulation signal, and to scale the modulation signal based on the actual gain characteristic in the second mode to provide gain compensation and frequency modulation of the DCO.