Disclosed is a method of producing a switching power converter which is implemented by providing a ring oscillator made up of a plurality of series-connected inverters. A feedback loop from the output of the last inverter in the series to an input lead of the first inverter in the series is provided. A selection circuit is provided which has a plurality of inputs and one or more outputs. An output of each of the inverters is connected to an associated input of the selection circuit. An exclusive OR gate is provided which has first and second inputs. The selection circuit is configured to selectively provide to the first input of the exclusive OR gate an output signal from an inverter in the string of series connected inverters, and further the selection circuit is configured to provide to the second input of the exclusive OR gate an output signal from an output lead of another inverter in the string of inverters.