An example controller for use in a power supply in accordance with the present teachings includes a drive signal generator, a jitter signal generator and a compensator signal generator. The drive signal generator is coupled to output a drive signal having a switching period and a duty ratio to control switching of a switch that is to be coupled to the controller. The jitter signal generator is coupled to provide a jitter signal, where the switching period of the drive signal varies in response to the jitter signal. The compensator signal generator is coupled to provide a compensator signal responsive to the jitter signal, where the duty ratio of the drive signal is varied in response to the compensator signal.