Small signal modeling of digital V2 control for buck converter with pulse frequency modulation

Pulse frequency modulation (PFM) includes constant on-time (COT) modulation and constant off-time (CFT) modulation. Digital V² control technique includes digital peak voltage (DPV) control and digital valley voltage (DVV) control. In this paper, DVV controlled buck converter with COT modulation and DPV controlled buck converter with CFT modulation are studied. Their control algorithms are introduced in detail. Based on which, small-signal models of digital PFM V² controlled buck converter are derived. Small-signal analysis is subsequently performed and compared between these two control methods.