Now there are other things called complex zero’s that are only possible in digital. The Power Architect software allows the designer to pick a complex zero, which is a type of anti-double pole. In a switching regulator there will be an inductor and capacitor in the power stage, that will create double pole, that means two poles, with some Q which results in some fast phase shift. The example shown here on the left is actually a measurement taken and shows performance of a switching regulator, and it shows the fast phase shift at the double pole frequency. It could ideally be offset with a complex zero, which is a double zero at a given frequency in a very fast phase shift.