Multi-level class-D amplifier by means of 3 physical levels

A method to generate virtual multi-level output pulses for a Class-D Amplifier, where the time-voltage-area corresponds to a multiple of digital levels, comprising:

• providing means to convert the input signal into ideal PDM (Pulse Density Modulated) power driver control pulses, means to generate a “pulse polarity” and a digital “pulse length select” signal, means to define a set of output pulse area reference values, a length-of-pulse-integrator to determine the pulse stop time, a pulse generator providing the power driver control pulses using, means for a Class-D power driver to drive voltage into an output load and means for an output load;
• converting said input signal into ideal PDM control pulses;
• generating said “pulse polarity” and said digital “pulse length select” signal, where said pulse length select signal represents multiple pulse-area values;
• defining said set of output pulse area reference values, one for each step of said multi-level output;
• determining said pulse stop time, based on said pulse start time (clock), on said digital “pulse length select” signal and based on said output pulse area reference values;
• generating said multi-level output pulses using said pulse start and pulse stop signals;
• applying said power driver control pulses to said Class-D power driver;
• and
• driving said power driver's output voltage to the output load (typically a loudspeaker).