Patent attributes
Pulse-width-modulating class D amplifier with an H-bridge output stage, and method of operating the same. in which output stage dead-time is compensated. Offset logic circuitry detects various dead-time-related conditions at push-pull output drivers, and generates an offset signal applied to the amplified differential input signal, to adjust the time at which the voltage at differential signal lines crosses a ramp reference waveform. The offset signal can correspond to the duration of a disturbance (dead-time at one driver in combination with an active signal at the active driver), or the sum of that disturbance duration with a dead-time at the active driver. The offset signal is generated by charging a capacitor for the duration of this disturbance, or disturbance plus dead-time. According to another approach, error is reduced by charging a capacitor for each transition of the signal for a duration of the dead-time of the active driver. Total harmonic distortion is reduced without requiring increased circuit complexity and without shortening the dead-time to unsafe margins.
