A non-linear multi-mode control method to improve the transient performance of voltage regulators

Digital adaptive voltage positioning (AVP) techniques with fast transient response for voltage regulator modules (VRMs) are proposed in this paper. An AVP control unit is used to achieve AVP, by generating dynamic voltage reference and dynamic current reference. Two digital-to-analog converters therefore can be used instead of analog-to-digital converters to reduce system complexity. A straightforward control law is implemented and no compensator is involved in the control loop, which greatly reduces the computation delay. And non-linear control, which reduces the transient-assertion-to-action delay and maximizes the inductor current slew rate, is used to improve the transient performance. Steady state analysis was performed to demonstrate the digital controller operation. At last, a two-phase 12 V-to-1 V/40 A 250 KHz synchronous buck converter with the proposed digital controller was designed to verify the theoretical analysis by simulations and experiments.