Abstract: Non-linearities in the sweep output of a voltage controlled oscillator are automatically linearized by a scheme that compensates for changes in slope of the variation in frequency with time during a high accuracy calibration mode, prior to placing the VCO into real time operation. During the calibration mode the sweep rate of the VCO is slowed down as the operational frequency range of interest is divided into a prescribed number of subfrequency segments or windows. During each window, an input control code, obtained from a random access memory (RAM) and representative of the intended slope of the VCO frequency sweep (for that window of interest), is applied to a digital-to-analog converter (DAC) whose output is integrated and applied to the voltage control input of the VCO.