An 84.7% Ef ficiency 100-MHz Package Bondwire-Based Fully Integrated Buck Converter With Precise DCM Operation and Enhanced Light-Load Efficiency Cheng Huang, Student Member , IEEE, and Philip K. T. Mok , Senior Member , IEEE

Abstract

A 100-MHz PWM fully integrated buck converter utilizing standard package bondwire as power inductor with en- hanced light-load ef ficiency which occupies 2.25 mm² in 0.13-µm CMOS is presented. Standard package bondwire instead of on-chip spiral metal or special s piral bondwire is implemented as power inductor to minimize the cost and the conduction loss of an integrated inductor. The accu racy requirement of bondwire inductance is relaxed by an extra di scontinuous-conduction-mode (DCM) calibration loop, which solves the precise DCM op eration issue of fully integrated conver ters and eliminates the reverse current-related loss, thus enab ling the use of standard package bondwire inductor with various packaging technique s. Optimiza- tions of the power transistors, the input decoupling capacitor (C ), and the controller are also presented to achieve an ef ficient and robust high-frequency design. With all three major power losses, conduction loss, switching loss, and reverse current related loss, optimized or eliminated, the ef ficiency is signi ficantly improved. An ef ficiency of 74.8% is maintained at 10 mA, and a peak ef- ficiency of 84.7% is measured at nominal operating conditions with a voltage conversion of 1.2 to 0.9 V. Converters with various bondwire inductances from 3 to 8.5 nH are m easured to verify the reliability and compatibility of different packaging techniques.