Multiphase low lc buck regulator

Abstract

A buck power converter creates a desired output voltage from a greater input voltage with higher efficiency than linear regulators or charge pumps. For compact-size and cost sensitive products, the use of the buck power converter is hindered mainly because of lack of physical space and increases in the cost of the passive components like the inductor and capacitor. Techniques are presented to reduce the sizes of the passive components so that they can be integrated on-chip or in-package or on board. A signal converter in the buck power converter determines the duty cycle of a switching control signal. The switching control signal would ordinarily have driven a power switching circuit that provides current to the inductor in the buck power converter. The signal converter outputs a modified (multiphase) switching control signal that includes multiple separated on-periods that taken together approximate the duty cycle of the switching control signal while maintaining the same control loop frequency. The multiphase switching signal drives the power switching circuit to provide current to the inductor during each of the multiple separated on-periods so that the output voltage ripple decreases by a factor of the number of phases in the modified switching signal. In this way, if the ripple amplitude is kept same, the sizes of the passive components can be reduced by the factor of the number of phases in the modified switching control signal.