A High Performance Switched Capacitor-Based DC-DC Buck Converter Suitable for Embedded Power Management Applications

Abstract

Here, we propose high performance buck converter architecture suitable for embedded applications. The proposed converter has high power efficiency, high power density, good driving capability, low output ripple, and good line and load regulation. The step down converter is constructed using a simple building block called cross coupled converter. As this block use low swing internal signals to control half of its switches, the required switching loss decreases and these internal control signals enable us to use thin oxide transistor for making switch smaller and reducing power further. In addition, converter uses all the good features of non-overlapping rotational interleaving switching scheme. Switching frequency of the converter is dynamically adjusted based on load current to maintain high power efficiency. Good transient performance is achieved by using dynamic leaker circuit with a marginal increase of static current. The converter is designed in 0.18- m CMOS process to get regulated 1.3-1.6 V output from 3.3 V input supply while output ripple is below 42 mV and provides 86% peak power. For 75% power efficiency, power density of the converter is 0.43 W/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> using total 490 pF capacitor.