Transient Output-Current Regulator With Background Calibration Applied to a Buck Converter for Fast Load-Transient Response

A transient output-current regulator (TOCR) is presented and merged into a buck converter to achieve fast load-transient response for stepwise load-current I-load profiles, leading to small undershoot/overshoot voltage V-US/V-OS and short settling time t(S) in the output voltage V-O. The TOCR instantly detects an I-load transient and triggers a compensation current I-U/I-D. Moreover, background calibration of the I-U/I-D is proposed to ensure the sum of inductor current I-L and I-U/I-D accurately tracks I-load under PVT variations. The prototype chip, fabricated in a 0.18-mu m CMOS process, occupies 1.88 mm(2). Under 0.45-A and 1-A I-load transients, the measured V-O remains within 1% of its nominal 1.8 V, with V-US and V-OS both being less than 18 mV and a negligible t(S). Compared with other state of the arts, this letter achieves the fastest load-transient response with the smallest V-US/V-OS and shortest t(S).