Method and apparatus for producing a pulse width modulated signal

摘要

A method and apparatus to produce a pulse width modulated (PWM) signal from pulse code modulated (PCM) data. In one embodiment, a crossing point of an analog signal with the ramp portion of a sawtooth waveform is approximated by first extrapolating, or projecting, a line between two adjacent sample points across other sample points to produce an estimate of the crossing point. A magnitude difference between a crossing point of the extrapolated line and a sample point magnitude on each side of the crossing point is determined. The magnitude difference, multiplied by an empirically determined constant, is added to the estimate. A PWM signal is then produced using the estimate for the crossing point. <IMAGE>