Spur-Free Switch-Mode Power Supplies

This paper describes spur-free switch-mode power supplies. Spur-free switching is a technique that eliminates the inherent spurious switching noise from the spectrum of all voltages and currents in switching power supplies. The elimination of spurious noise allows these supplies to directly power noise-sensitive loads (IoT, RF, or SoC applications) or be integrated with them on the same die without degrading their performance, which leads to significant improvement in the system's overall power efficiency. The paper highlights spur-free switching within PWM, PFM, and hysteretic controllers, as well as a universal spur-free switching scheme that can be incorporated within any type of controller. Adopting spur-free switching in dual-frequency SIMO power supplies with on-chip outputs will also be discussed.