A digital PID controller for controlling the operation of a switching power converter is disclosed. A data converter is provided for converting the analog sense voltage to a digital sense voltage. A difference circuit then determines the difference between the digital sense voltage and a reference voltage as a digital error voltage, which reference voltage represents a desired output DC voltage for the power converter. A digital compensator processes the digital error voltage. The digital compensator includes a PID compensation network for compensating the digital error signal with a discrete time PID control law and a postprocessing filter for processing the output of the PID compensation network, comprised of a sinc filter with variable parameters to define the operating characteristics thereof, such that a first notch associated therewith can be placed at a desired frequency. A switching control signal generator generates switching control signals for controlling the operation of the power converter, wherein the digital compensator and the switching control signal generator operate to minimize the digital error signal. A controller for controls the operation the digital compensator to define the operating characteristics of the sinc filter.