Design of low-power and high slew-rate error amplifier for fast transient CMOS buck converters

The voltage boosting control (VBC) is presented to achieve low-power and high slew-rate error amplifier for enhancing the load transient response of dc-dc converters. The VBC is employed to increase/decrease the gate voltages of the output-stage transistors of the error amplifier, leading to large current driving capability with simple circuitry during transient. In addition, the accelerative scheme of the error amplifier is switched off in steady state for power saving. A buck converter with the VBC method is designed with 0.35-µm 2P4M CMOS technology. Compared without the VBC, the experimental results show that the output voltage variation and recovery time of the buck converter with the VBC are enhanced by over two times and ten times, respectively, for load current change between 50 mA to 500 mA.