Abstract: A phase-locked loop frequency synthesizer apparatus for providing an output signal whose frequency jumps from one value to another, at regular intervals of time. Coarse tuning circuitry couples a prescribed signal to the apparatus' voltage-controlled oscillator (VCO), to drive the VCO immediately to the correct frequency each time a new frequency is selected, thereby substantially reducing the apparatus' settling time. In addition, adaptive coarse tuning circuitry continuously updates the values of stored coarse tuning information for each possible frequency, to correct for any drifts in the VCO's voltage/frequency characteristic. A VCO gain normalizer circuit amplifies the error signal coupled to the VCO by an amount that varies with the selected frequency, so as to correct for any non-uniformities in the apparatus' various elements, particularly the VCO, and to thereby provide a uniform loop gain.