Area- and Power-Efficient Monolithic Buck Converters With Pseudo-Type III Compensation Patrick Y . Wu, Student Member , IEEE, Sam Y . S. Tsui, and Philip K. T. Mok , Senior Member , IEEE

Abstract

Monolithic PWM voltage-mode buck converters with a novel Pseudo-Type III (PT3) compensation are presented. The proposed compensation maintains the fast load transient response of the conventional Type III compensator; while the Type III compensator response is synthesized by adding a high-gain low-frequency path (via error amplifier) with a moderate-gain high-frequency path (via bandpass filter) at the inputs of PWM comparator. As such, smaller passive components and low-power active circuits can be used to generate two zeros required in a Type III compensator. Constant /71/109 /67biasing technique can also be adopted by PT3 to reduce the process variation of passive components, which is not possible in a conventional Type III design. Two prototype chips are fabricated in a 0.35- m CMOS process with constant /71/109 /67biasing technique being applied to one of the designs. Measurement result shows that converter output is settled within 7 s for a load current step of 500 mA. Peak efficiency of 97% is obtained at 360 mW output power , and high efficiency of 86% is measured for output power as low as 60 mW. The area and power consumption of proposed compensator is reduced by /55/53% in both designs, compared to an equivalent conventional Type III compensator.