Design and Analysis of a Buck–Boost DC–DC Converter with Delta-Sigma Modulator Controller

Abstract

This paper presents a low-ripple and high-efficiency buck–boost DC–DC converter with delta-sigma modulator controller that converts 1.8 V to 1.2 V and 3.3 V. A current and voltage closed-loop controller has been designed to achieve better performance simultaneously such as lower settling-time, steady-state error and over shoot and under shoot. The converter is started in the current controller mode initially, when the output voltage approaches the desired value, the power stage is controlled with the voltage controller mode. PI compensator and a third-order delta-sigma modulator are utilized in the voltage mode. Also, the closed-loop stability of the designed converter has been analyzed with Lyapunov method using converter nonlinear model. This work has been simulated in MATLAB-SIMULINK environment. The performance results show that the maximum efficiency of the closed-loop DC–DC converter is 90% at 5[Formula: see text]MHz switching frequency, and the output voltage ripple is 0.5% and 0.6% for the buck and boost modes, respectively. Also, the simulation results demonstrate the closed-loop stability of the converter in the presence of 10% load variation.