A New Digital Adaptive Voltage Positioning Technique with Dynamically Varying Voltage and Current References

A digital adaptive voltage positioning (Digital AVP) technique with fast transient response for voltage regulators (VRs) is proposed in this paper. In this proposed digital control architecture, two digital-to-analog converters (DACs) are used instead of analog-to-digital converters (ADCs), thus significantly reducing system complexity. Both the voltage and current references are changed dynamically at DAC clock frequency resulting in fast transient response. Different from other control methods (the output voltage tracks the voltage reference), the generated voltage reference is always trying to track the output voltage. A straightforward control law is used, which does not require compensator. Moreover, the proposed control technique automatically avoids the limit cycle by automatic dithering method. Further, it allows the use of non-linear control methods which significantly improve transient response speed. Finally, a two-phase 12V-to-1V, 40A, 250 kHz synchronous buck converter with the proposed digital controller was designed to verify the theoretical analysis by simulation and experimental results.