an apparatus which outputs very low duty cycle pulses of a consistent width . it is common to use a pulse width modulator as part of a liquid crystal display dimming system to vary the brightness . in the typical pulse width modulating scheme for lamp dimming , certain noise irregularities may appear at the beginning of a ramping voltage . these irregularities result in pulse widths which vary greatly . in the present invention , the slope of the ramping voltage is greatly increased at the beginning of the period , thus making the comparison between the reference voltage and the ramping voltage more accurate .