Stability analysis and large signal behavior of a high performance voltage regulator with non-linear multi-mode digital control

Abstract

A novel digital adaptive voltage positioning (digital AVP) technique was proposed in [11]. Good transient performance had been achieved without using complicated control. In this paper, a small signal model is proposed for this mixed-signal digital controller. It is revealed by this small signal model that the inner current loop is in analog and the voltage loop is in digital, thus the controller can benefit from both: having valuable features of digital control but without limitations such as limit cycle. On the other hand, dynamic behavior of the voltage regulator with this digital AVP controller under large load transient is analyzed. With optimized bandwidth designed for switching stability, the VR with the digital AVP controller exhibits very excellent dynamic performance because of non-linear multi-mode control.