Multiple pulse width modulation (PWM) generators each have a separate phase offset counter creating a phase shift. The phase shifting process is separated from the duty cycle generation process, thereby easing the task of preserving the duty cycle and phase relationships among the various PWM channels following an asynchronous external synchronization event. A master time base generates a PWM cycle start signal that resets the phase offset counters in each of the PWM generator circuits. The phase offset counter continues counting until it matches the respective phase offset value. Then, the associated duty cycle counter is reset and restarted. The duty cycle continues until its count matches the specified value at which time the duty cycle counter stops until reset by the terminal count from the phase offset counter. The output of the duty cycle comparators provide the output PWM signals as a repetitive series of single cycle PWM signals.