| 摘要 |
<p>A calibration system for an asymmetrical ramp generator for a pulse width modulator includes a complementary clock circuit (152); a first symmetrical dual ramp generator (156) for generating first and second ramps; a comparator device (158, 160) for generating first and second asymmetrical drive signals; a second asymmetrical dual ramp generator (162, 164) for generating third and fourth asymmetrical overlapping ramps; a calibration circuit (304); a first current splitting circuit (176) for establishing a reference level; a second current splitting circuit (176) for providing slew rate currents to the first (156) and second (162, 164) ramp generators for controlling the slew rate of the ramps; a current stepping device (320) for varying the current to the second current splitting circuit; the calibration circuit (304) including means (332) for fixing the current provided by the current stepping device (320) to the first and second ramps, simultaneously calibrating the third and fourth ramps, stopping the calibration, and returning the reference level to within the predetermined voltage range.</p> |
