A diode emulator for a DC--DC buck converter employs a variable current
ramp-based circuit that monitors the state of the phase voltage at the
common node between two power switching devices. Incrementally with each
pulse width modulation cycle, the diode emulator adjusts the time of
turn-off of the lower power switching device, until the monitored phase
voltage indicates that the emulator is effectively tracking the negative
going, zero-crossing of the ripple current through an output inductor.
