What is the definition of a Class D amplifier?

What is the definition of a Class D amplifier?

Note: For clarity, signal periods are not shown to scale. A class-D amplifier or switching amplifier is an electronic amplifier in which the amplifying devices (transistors, usually MOSFETs) operate as electronic switches, and not as linear gain devices as in other amplifiers.

What is the structure of a Class D Power Stage?

The structure of a class-D power stage is somewhat comparable to that of a synchronously rectified buck converter (a type of non-isolated switched-mode power supply (SMPS) ), but works backwards.

How is a Class D amplifier different from a buck converter?

Whereas buck converters usually function as voltage regulators, delivering a constant DC voltage into a variable load and can only source current (one-quadrant operation), a class-D amplifier delivers a constantly changing voltage into a fixed load, where current and voltage can independently change sign (four-quadrant operation).

How does a half bridge Class D amplifier work?

A half-bridge Class D amplifier however is different, as the energy flow can be bi-directional, which leads to the “Bus pumping” phenomena, which causes the bus capacitors to be charged up by the energy flow from the load back to the supply. This occurs mainly at the low audio frequencies i.e. below 100Hz.

What is the PSRR of a Class D amplifier?

This means that the power supply rejection ratio (PSRR) of a Class D amplifier is 0dB, whereas the PSRR of a linear amplifier is very good. It is common in Class D amplifiers to use feedback to compensate for the bus voltage variations.

What’s the difference between SMPS and Class D amplifier?

Unlike a SMPS, the amplifier has a much more critical job to do, to keep unwanted artifacts out of the output. Feedback is almost always used, for the same reasons as in traditional analog amplifiers, to reduce noise and distortion. Theoretical power efficiency of class-D amplifiers is 100%.