In some embodiments, a threshold calibration system to provide a zero voltage switching signal is presented. The system includes a divider coupled to a switching node; a calibration ramp generator; a reference voltage generator; a comparator; a first multiplexer coupled to receive a divider output signal from the divider and a calibration ramp signal from the calibration ramp generator and provide a signal to the comparator based on a calibration enable signal; a second multiplexer coupled to receive reference voltages from the reference voltage generator, the second multiplexer provided a threshold signal to the comparator; and a digital feedback circuit receiving an output signal from the comparator and providing the zero voltage switching signal.