A Ripple-Based Constant On-Time Controlled DC-DC Buck Converter with Inductor Current Sensing Technique

This letter implements a ripple-based constant on-time (RBCOT) buck converter with a fast transient response fabricated in the TSMC
$0.18 \mu \mathrm{m}$
CMOS process. The steady-state measurement shows that this chip can regulate output voltage from 0.9V to 1.8V while the input voltage is set at 3.3V and the output load current varies from 0.1A to 1A. The load transient response shows that when the output voltage is 0.9V, the undershoot voltage is 78m V and the overshoot voltage is 126m V. The settling time is
$2.8\mu \mathrm{s}$
for a step-up load and
$2.5\mu \mathrm{s}$
for a step-down load. The chip area is 0.922 mm2, The maximum efficiency is 92.32%. This work improves the traditional inductor current ramp compensation technique. Here, we utilize an accurate transconductance amplifier to amplify the inductor current, increasing system stability and efficiency. By adopting negative inductor current feedback to improve the transient response. Through the V
²
controlled dual loop structures to eliminate the output dc voltage offset issues.