Improved V2 COT Control with State Plane Trajectory Control

Virginia Li: Voltage regulator (VR) for smartphone CPU and GPU applications need to meet fast dynamic voltage scaling (DVS) and load transient requirements. Constant On-Time Control (COT) is a popular variable-frequency control in VR applications due to high light-load efficiency and high-bandwidth design to achieve fast transient. In addition, the V2 variation of COT is able to achieve fast DVS tracking capability and simple to implement. For fast load transient, it is possible for COT to lose control for a period of time. As a result, the output voltage not only have a large undershoot but also a ring-back before control is regained. The best transient response is a single-cycle response. Prior arts to realize single-cycle response involves complicated algorithm which need to be digitally implemented. In this paper, an improved method to improve V2 COT using state-trajectory control is proposed with analog implementation.