High Performance Integrated Controller with Variable Frequency Control for Switching DC-DC Converters

Abstract

Development of digital core chips poses serious challenges to the power supply design. High performance switching DC-DC converter must meet requirements of high current, low voltage tolerance, fast transient response, high power efficiency, small profile and low cost. The conventional PWM control with constant switching frequency has limitation to improve both transient response and power efficiency because there is a conflicting requirement on switching frequency. The control scheme with variable frequency has promising features to achieve better overall performance, but the issues in the reported design approaches limit their usefulness in the practical applications. This dissertation reviews and summarizes the issues and the design considerations in the high current switching DC-DC converters. To improve the system performance, novel control architecture with variable switching frequency and novel implementation of the integrated controller are proposed in this dissertation. The proposed control architecture is modeled and analyzed. Fully differential circuits are designed to implement the control core functions. The design methodology and the design considerations are discussed. The control concept and the proposed circuits are verified by the prototype controller chip.