Switching amplifiers

A controller for controlling an output stage of a switching amplifier to drive a load connected between first and second output nodes with a differential drive signal based on an input signal, wherein:

• the controller is configured to be operable to control the output stage to modulate each of first and second output nodes between respective selected switching voltages of a set of at least three switching voltages in switching cycles to generate the differential drive signal;
• and
• the controller is configured to control the modulation of the first and second output nodes so to dynamically vary a common-mode voltage applied to the first and second output nodes with input signal amplitude over at least a first range of input signal amplitude.

A controller for controlling an output stage of a switching amplifier to drive a load connected between first and second output nodes with a differential drive signal based on an input signal, wherein:

• the controller is configured to be operable to control the output stage to modulate each of first and second output nodes between respective selected switching voltages of a set of at least three switching voltages in switching cycles to generate the differential drive signal;
• and
• the controller is configured to control the modulation of the first and second output nodes so to dynamically vary a common-mode voltage applied to the first and second output nodes based on a power budget for power draw from a first power supply for providing one of the switching voltages of the set of at least three switching voltages.

A controller for controlling a multichannel driver having a plurality of channels, each channel comprising a respective switching amplifier for driving a respective load connected between respective first and second output nodes with a respective differential drive signal based on a respective input signal, wherein:

• the controller is configured to be operable to control each switching amplifier to modulate each of first and second output nodes between respective selected switching voltages of a set of at least three switching voltages in switching cycles to generate the differential drive signal;
• and
• the controller is configured to control at least one of the switching amplifiers so to dynamically vary a common-mode voltage applied to the respective first and second output nodes to control an overall power draw from a first power supply for providing one of the switching voltages of the set of at least three switching voltages from all of the switching amplifiers.