Cycle-borrow digital valley current control of buck DC-DC converter

The digital double loop current control become the promising technique for digital switching DC-DC converters. In this paper a novel current control technique, named cycle-borrow control is proposed and studied, which has faster loop transient response than the time delay control, and its requirement to loop processing speed can be relaxed as compared with the deadbeat current control. The cycle-borrow valley current control laws of buck DC-DC converters with four different pulse width modulations are derived, and their stabilities are analyzed. A simple digital slope compensation (DSC) method which doesn´t need any extra slope compensation circuit is proposed to eliminate the sub-harmonic oscillations of cycle-borrow control. The simulation results show that, the transient response performance of dual-edge modulations is better than that of single-edge modulations. The cycle-borrow control technique is especially benefit to high-frequency digitally controlled switching DC-DC converters.