Linear or switching amplifier at PHIL

Linear amplifiers operate in the linear region of semiconductor components. These amplifiers normally have a good frequency response above 10kHz. A disadvantage of these amplifiers is that they are often less efficient and large in size. This must be taken into account in high-power applications.

Switching amplifiers operate in the saturation region of the switching element. By design, they are much more efficient (> 90%) and better suited for absorbing energy, and they typically have higher power in a more compact package compared to linear amplifiers. A disadvantage is that they generally have a lower bandwidth depending on the PWM frequency and filtering. New designs of switching amplifiers can now achieve a bandwidth of 5 kHz and higher using faster switching elements such as the newer SiC and GaN transistors.

The safe operating range of linear and switching power supplies can be quite different, especially when it comes to current overload. Some amplifiers, usually the linear ones, consume extra power which then translates into a lot of heat dissipation. Others can deliver extra power to the grid. These high-quality regenerative amplifiers are much more efficient because less power is lost to heat.

Selecting the source and sink capabilities of an amplifier therefore depends largely on the application. Once these have been chosen, the next logical step is to select the appropriate bandwidth.