Influence of non dominant poles

Non-dominant poles are poles that do not contribute to the bandwidth of the servo function. They do not significantly change the dynamic response of the amplifier if their frequency is much larger than the bandwidth of the servo function. If not, extra measures have to be taken to reduce their influence. All high-frequency compensation techniques discussed in this chapter can be applied for this purpose.

Bandwidth limitation with phantom zeros

Although bandwidth limitation with the aid of phantom zeros is a powerful technique, care has to be taken while applying it. The increase of the loop gain and of the servo bandwidth established by the phantom zero may turn non-dominant poles (before compensation) into dominant ones. This may pose limits to the application of this technique.