Abstract: A sweep control circuit and method for maintaining a constant swept frequency range of a voltage-controlled oscillator when switching between linear and non-linear sweeping functions is provided. The sweep control circuit includes a linear amplifier and an antilogarithmic amplifier, each of which has an output voltage window that is matched to the linear dynamic range of the CVO. Independently selected start and stop voltages are adjustable over the entire linear range of the VCO to set the lower and upper frequency limits as desired for either a linear or a logarithmic sweep. Log converters are utilized to map the linear start and stop voltages to logarithmic counterparts so that the VCO frequency does not shift when switching from one function to the other. This permits a single start frequency control and a single stop frequency control to be employed. A ramp voltage, which is appropriately scaled for both the linear and logarithmic functions, is applied to sweep the VCO.