Ripple Suppression of On-Chip Switched-Inductor Power Supplies

Emerging applications demand compact, battery-powered, and highly functional microsystems that require on-chip integration, low average power, and high peak-to-average power ratios. Switched inductors are popular power supplies because they are power efficient. Switching a power inductor, however, generates a nonlinear current ripple that is often difficult to tolerate and manage. The problem is more severe with on-chip nH inductors and pF capacitors. This paper explores how switching power supplies can manage and reduce this ripple. Although multiphase and filter suppressors help, analog cancellation can be 38× to 77× more effective, but also less power efficient and 23× to 55× more sensitive to mismatch from drift.