An 84.7% Efficiency 100-MHz Package Bondwire-Based Fully Integrated Buck Converter With Precise DCM Operation and Enhanced Light-Load Efficiency

A 100-MHz PWM fully integrated buck converter utilizing standard package bondwire as power inductor with enhanced light-load efficiency which occupies 2.25 mm2 in 0.13-μm CMOS is presented. Standard package bondwire instead of on-chip spiral metal or special spiral bondwire is implemented as power inductor to minimize the cost and the conduction loss of an integrated inductor. The accuracy requirement of bondwire inductance is relaxed by an extra discontinuous-conduction-mode (DCM) calibration loop, which solves the precise DCM operation issue of fully integrated converters and eliminates the reverse current-related loss, thus enabling the use of standard package bondwire inductor with various packaging techniques. Optimizations of the power transistors, the input decoupling capacitor (CI), and the controller are also presented to achieve an efficient and robust high-frequency design. With all three major power losses, conduction loss, switching loss, and reverse current related loss, optimized or eliminated, the efficiency is significantly improved. An efficiency of 74.8% is maintained at 10 mA, and a peak efficiency 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 measured to verify the reliability and compatibility of different packaging techniques.

[1]  T.Y. Man,et al.  A 0.9-V Input Discontinuous-Conduction-Mode Boost Converter With CMOS-Control Rectifier , 2008, IEEE Journal of Solid-State Circuits.

[2]  R. Harjani,et al.  A High-Efficiency DC–DC Converter Using 2 nH Integrated Inductors , 2008, IEEE Journal of Solid-State Circuits.

[3]  Ramesh Harjani,et al.  Fully integrated on-chip DC-DC converter with a 450x output range , 2010, IEEE Custom Integrated Circuits Conference 2010.

[4]  Michiel Steyaert,et al.  A fully-integrated 0.18μm CMOS DC-DC step-down converter, using a bondwire spiral inductor , 2008, 2008 IEEE Custom Integrated Circuits Conference.

[5]  Bill Liu,et al.  An 80% peak efficiency, 0.84mW sleep power consumption, fully-integrated DC-DC converter with buck/LDO mode control , 2011, 2011 IEEE Custom Integrated Circuits Conference (CICC).

[6]  Chi-Ying Tsui,et al.  A pseudo-CCM/DCM SIMO switching converter with freewheel switching , 2002, 2002 IEEE International Solid-State Circuits Conference. Digest of Technical Papers (Cat. No.02CH37315).

[7]  M. Steyaert,et al.  A fully-integrated 130nm CMOS DC-DC step-down converter, regulated by a constant on/off-time control system , 2008, ESSCIRC 2008 - 34th European Solid-State Circuits Conference.

[8]  Kai Strunz,et al.  A 20 mV Input Boost Converter With Efficient Digital Control for Thermoelectric Energy Harvesting , 2010, IEEE Journal of Solid-State Circuits.

[9]  K. T. Mok,et al.  A package bondwire based 80% efficiency 80MHz fully-integrated buck converter with precise DCM operation and enhanced light-load efficiency , 2012, 2012 IEEE Asian Solid State Circuits Conference (A-SSCC).

[10]  B. Bakkaloglu,et al.  A Multi-Stage Interleaved Synchronous Buck Converter with Integrated Output Filter in a 0.18/spl mu/ SiGe process , 2006, 2006 IEEE International Solid State Circuits Conference - Digest of Technical Papers.

[11]  R.B. Ridley,et al.  A new continuous-time model for current-mode control with constant frequency, constant on-time, and constant off-time, in CCM and DCM , 1990, 21st Annual IEEE Conference on Power Electronics Specialists.

[12]  Alessandro Piovaccari,et al.  A CMOS low-power, high-speed, asynchronous comparator for synchronous rectification applications , 2000, 2000 IEEE International Symposium on Circuits and Systems. Emerging Technologies for the 21st Century. Proceedings (IEEE Cat No.00CH36353).

[13]  Youngkook Ahn,et al.  A 50-MHz Fully Integrated Low-Swing Buck Converter Using Packaging Inductors , 2012, IEEE Transactions on Power Electronics.

[14]  Wing-Hung Ki,et al.  Ultra Fast Fixed-Frequency Hysteretic Buck Converter With Maximum Charging Current Control and Adaptive Delay Compensation for DVS Applications , 2008, IEEE Journal of Solid-State Circuits.

[15]  Gyu-Hyeong Cho,et al.  Robust and efficient synchronous buck converter with near-optimal dead-time control , 2011, 2011 IEEE International Solid-State Circuits Conference.