MULTI-LEVEL CLASS-D POWER AMPLIFIER HAVING PULSE CODED DIGITAL INPUT SIGNAL AND USING TWO-LEVEL AMPLIFIER STAGE

摘要

PURPOSE: A multi-level class-D power amplifier having a pulse coded digital input signal and using a two-level amplifier stage is provided to maximize power efficiency by using multi-level pulse widths to reduce a pulse-sampling rate. CONSTITUTION: The device includes sigma delta modulator(31), pulse area translation and pulse width control function(32), push-pull driver(33). A signal conversion unit converts an input signal into a PDM(Pulse Density Modulated) signal. A generation unit generates an output of the PDM as a signal to represent desired multiple pulse area values. A determination unit determines a required length-ratio of positive and negative pulse parts within one sampling period, where the pulse length ratio represents the multiple pulse area values. A definition unit defines a set of output pulse area values. A control unit controls the time of pulse phase changes within one sampling period. A pulse generator is used for providing virtual multi-level output pulses to a power driver. A unit for a Class-D power driver drives voltage into an output load controlled by the power driver pulses, typically a Complementary-Pair-Driver or an equivalent circuit. A load unit is used for an output load as the amplifier's output target.