Abstract: 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.

Abstract: An amplifier which outputs a nonlinear function in response to a linear input. The nonlinear response is a piece-wise linear approximation. The circuit includes an op amp which outputs a ramping voltage and a series of stages which change the scope of the ramping voltage. As the output of the op amp reaches a particular breakpoint, an additional stage of the circuit is activated so as to change the slope of the output. The new line segment has a new slope such that the combination of all these stages approximates a nonlinear response.