A MOS current-mode buck DC-DC converter with a 240-kHz loop bandwidth and unaltered frequency characteristics using a quadratic and input-voltage- dependent compensation slope

Abstract

In this study, we verified that a quadratic slope was the best-fit compensation slope for the current feedback loop of a current-mode DC-DC converter by considering the stability of the inductor current when the current disturbance was applied. We also verified that the introduction of the input voltage dependency to the quadratic slope enabled the frequency characteristics of the current feedback loop to remain completely constant without depending on the input and output voltage change of a DC-DC converter. The test chip of a MOS current-mode buck DC-DC converter using a 0.35-μm CMOS process and a 5-MHz clock realized two loop frequency bandwidths of 130 kHz and 240 kHz and was operated in two different input and output voltage settings for each frequency bandwidth. As a result, the unaltered gain and phase frequency characteristics were obtained for two different settings in each frequency bandwidth. © 2009 IEEE.