Area-efficient error amplifier with current-boosting module for fast-transient buck converters

摘要

The current boosting module (CBM) is proposed to be implemented in an error amplifier (EA) for improving the load transient of a dc-dc converter. To enhance the slew rate of the EA during transient, the CBM is adopted to raise/reduce the gate voltages of the output-stage transistors of the EA for enhancing its current driving capability with simple circuitry. Moreover, to save power consumption in steady state, the accelerative mechanism of the EA is turned off. A buck converter with CBM is implemented with 0.35 μm 2P4M complementary metal-oxide-semiconductor process. The experimental results demonstrate that the recovery time and transient ripple of the buck converter are improved by over ten times and two times, respectively, compared with those of the buck converter without CBM, for a 450 mA load current change. The maximum power conversion efficiency is 92.8% when the input and output voltages are 4 and 2.5 V, respectively. Hence, the buck converter with CBM can concurrently fulfil the functionalities of fixed switching frequency and fast load transient.