A current-mode buck converter with bandwidth reconfigurable for enhanced efficiency and improved load transient response

Abstract

Current-mode control is commonly used in buck converters. Many current-mode buck converters with variable-frequency controllers have been published for smaller inductance and maintaining efficiency via fast and slow frequency, respectively. However, bandwidth of the current-mode buck converter with fixed compensation coefficients is limited by the lowest switching frequency, thus decreases transient speed. This paper proposes a current-mode buck converter with reconfigurable compensation coefficients controlled by a switched-capacitor compensator and activated by a transient detector. Fabricated in 0.35μm CMOS process, this chip occupying 0.91mm2 achieves 96.3% peak efficiency. A 5μs settling time is measured with 75mV undershoot for 700mA load transition.