In conventional pulse width modulation systems a ramp is intersected by two variable references to accomplish dual edge modulation (DEM), by a fixed and a variable reference for trailing edge modulation (TEM), and by a variable and a fixed reference for leading edge modulation (LEM). Generally such systems operate satisfactorily but inaccuracies and unreliability can occur at the extremes: when zero width pulses and maximum width pulses are generated. For example, when maximum width pulses are requested the full width available from the ramp cannot be utilized because there must be some overshoot of the ramp to intersect the reference. When zero width pulses are requested it is likewise difficult to rely on the ramp instantaneously responding to the references to emit absolutely no pulse: some small spikes may get through. Attempts to address these problems have resulted in the use of additional external circuits to fill and blank the pulses.