Switching/Linear Hybrid Audio Power Amplifiers for Domestic Applications, Part 2: The Class-B+D Amplifier
The analysis and design of a series switching/linear hybrid audio power amplifier rated at 100 W into 8 O are presented. A high-fidelity linear stage controls the output, while the floating mid-point of the power supply for this linear stage is driven by a switching stage. This keeps the voltage across the linear stage output transistors low, enhancing efficiency. Analysis shows that the frequency responses of the linear and switching stages must be tightly matched to avoid saturation of the linear stage output transistors. The switching stage employs separate DC and AC feedback loops in order to minimize the adverse effects of the floating-supply reservoir capacitors, through which the switching stage output current must flow.
This paper costs $33 for non-members and is temporarily free for AES members.