A signal generator comprises (i) a first set of capacitors at least partially switchably connectable for adjusting a frequency of an oscillator as part of a phase-locked loop and (ii) a second set of capacitors comprised in one or more oscillator control subsystems. A method of controlling the signal generator comprises: (i) acquiring a frequency lock in the phase-locked loop, (ii) calculating, in conjunction with the acquiring of the frequency lock, a systematic capacitance error of the first set of capacitors due to process, voltage, and temperature variations based on the frequency of the oscillator and a switching state of the first set of capacitors, and (iii) calibrating the one or more oscillator control subsystems using the systematic capacitance error, thereby compensating for process, voltage, and temperature variations common between the first set of capacitors and the second set of capacitors.