Minimum on time, dual supply class D amplifiers with ground speaker returns and methods of class D amplification

摘要

Class D amplifiers and methods of amplification wherein a load is periodically coupled to a positive power supply connection through a first switch or a negative power supply connection through a second switch for a period responsive to an input signal. A third switch couples the load to a circuit ground connection during times when the load is not coupled to either the positive or the negative power supply connection. This provides a load current recirculation path through the ground connection, which together with the inductance of the load, tends to maintain the load current when both the first and second switches are open. Loads such as speakers may be directly connected to the amplifier output, or may be coupled to the amplifier output through a filter. Various exemplary control methods, including use of feedback, are disclosed.