Ich kenne den Ausspruch: we have come full circle.

This phrase could give a sense of finality ("the cycle is complete"), but most likely it refers to circular logic (which is where you try to prove something merely by saying it in a different way) or just the logical discovery that your final conclusion is the same as your original idea.

@andalasur: The German sentence is a set phrase, which should be translated by a set phrase in English, too. "circle is complete" is no such phrase.