A system and method capable of injection locking the phases of a peak-valley multiphase regulator includes comparing an output voltage error signal with a ramp control signal and providing a corresponding slope reset signal, using transitions of the slope reset signal to develop a equally spaced high side ramp signals and equally spaced low side ramp signals, and injecting a corresponding one of the high side signals and a corresponding one of the low side ramp signals into each of the phases which correspondingly develop equally spaced pulse control signals for multiphase operation. Such injection locking allows the additional phases to operate out of phase with the first phase and allows operation at high duty cycles.