A novel digital adaptive voltage positioning (digital AVP) technique with dual-voltage-loop was proposed in. 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. Decoupling between bandwidth and large transient response with this novel digital AVP controller is verified.