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 Iload 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 Iload 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 Iload under PVT variations. The prototype chip, fabricated in a 0.18-μm CMOS process, occupies 1.88 mm2. 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
.