A 10-30 MHz Voltage-Mode Buck Converter With Linear Comparator-Free V2D controller

This brief proposes a voltage-mode pulse-width modulation (PWM) buck converter that can operate from 10 MHz to 30 MHz with a linear comparator-free voltage-to-duty-cycle (V2D) controller. The V2D controller replaces main comparator with an inverter and uses a comparator-free ramp generator with negative feedback, to enlarge the switching frequency and the tunable duty cycle range which are limited by the delay of comparators in conventional design. A high-slew-rate buffer used for ramp generator with variable starting point is presented. The buck converter was fabricated in a
$0.18~\mu \text{m}$
CMOS process. The output voltage ranges from 0.2 V to 3 V with 3.3 V input at both 10 MHz and 30 MHz, corresponding to a wide tunable duty cycle range of 0.85. The peak efficiency is 90.6% measured at 30 MHz with 2.7 V output and 300 mA load current, and the maximum load current is 1 A.