High-Efficiency Fully Integrated Switched-Capacitor Voltage Regulator for Battery-Connected Applications in Low-Breakdown Process Technologies

Conventional implementations of fully integrated, battery-connected, switched-capacitor voltage regulators (SCVRs) require either thick-oxide mosfets or stacked thin-oxide mosfets as power switches to sustain the voltage stress induced by a nominal 3.7-V Li-ion battery voltage. These approaches, however, exacerbate power loss, thus unable to achieve good power efficiency. Therefore, this paper proposes a solution to overcome the breakdown issue while improving the power efficiency by using only nonstacked, thin-oxide mosfets. This is realized by using a three-state, low-voltage-stress SCVR with a cross-phase-switching technique to decrease the output impedance and increase the total equivalent capacitance in a multiphase configuration. A prototype 3:1 SCVR is implemented fully on-chip in a standard 130-nm CMOS process. The chip is capable of delivering a maximum load current of 45 mA with an input voltage range from 3.2 to 4 V. Measurement results show 78–80% efficiency over a range of output power 4–28 mW, and a power density up to 38 mW/nF. The measured output ripple is 30–50 mV over a load range of 11–45 mA, and the measured voltage droop is 69 mV with 200-ns settling time under a 13-mA load step.

[1]  Michael D. Seeman,et al.  Analysis and Optimization of Switched-Capacitor DC–DC Converters , 2008 .

[2]  Nicolas Butzen,et al.  Design of Soft-Charging Switched-Capacitor DC–DC Converters Using Stage Outphasing and Multiphase Soft-Charging , 2017, IEEE Journal of Solid-State Circuits.

[3]  Dongsheng Ma,et al.  A 100-MHz Breakdown-Resilient Power Converter With Fully Monolithic Implementation on Nanoscale CMOS Process , 2015, IEEE Transactions on Industrial Electronics.

[4]  J. F. Dickson,et al.  On-chip high-voltage generation in MNOS integrated circuits using an improved voltage multiplier technique , 1976 .

[5]  Jason T. Stauth,et al.  A 3-Phase Resonant Switched Capacitor Converter Delivering 7.7 W at 85% Efficiency Using 1.1 nH PCB Trace Inductors , 2015, IEEE Journal of Solid-State Circuits.

[6]  Rongxiang Wu,et al.  High-Efficiency Silicon-Embedded Coreless Coupled Inductors for Power Supply on Chip Applications , 2012, IEEE Transactions on Power Electronics.

[7]  Jaydeep Kulkarni,et al.  A 0.45–1 V Fully-Integrated Distributed Switched Capacitor DC-DC Converter With High Density MIM Capacitor in 22 nm Tri-Gate CMOS , 2014, IEEE Journal of Solid-State Circuits.

[8]  Pavan Kumar Hanumolu,et al.  10.3 A 94.2%-peak-efficiency 1.53A direct-battery-hook-up hybrid Dickson switched-capacitor DC-DC converter with wide continuous conversion ratio in 65nm CMOS , 2017, 2017 IEEE International Solid-State Circuits Conference (ISSCC).

[9]  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.

[10]  John Crossley,et al.  A sub-ns response fully integrated battery-connected switched-capacitor voltage regulator delivering 0.19W/mm2 at 73% efficiency , 2013, 2013 IEEE International Solid-State Circuits Conference Digest of Technical Papers.

[11]  Hou-Ming Chen,et al.  A Two-Phase Fully-Integrated DC–DC Converter With Self-Adaptive DCM Control and GIPD Passive Components , 2015, IEEE Transactions on Power Electronics.

[12]  Luca P. Carloni,et al.  A 2.5D integrated voltage regulator using coupled-magnetic-core inductors on silicon interposer delivering 10.8A/mm2 , 2012, ISSCC.

[13]  Seung Wook Yoon,et al.  Advanced wafer level technology: Enabling innovations in mobile, IoT and wearable electronics , 2015, 2015 IEEE 17th Electronics Packaging and Technology Conference (EPTC).

[14]  Elad Alon,et al.  Design Techniques for Fully Integrated Switched-Capacitor DC-DC Converters , 2011, IEEE Journal of Solid-State Circuits.

[15]  Michiel Steyaert,et al.  Monolithic Capacitive DC-DC Converter With Single Boundary–Multiphase Control and Voltage Domain Stacking in 90 nm CMOS , 2011, IEEE Journal of Solid-State Circuits.

[16]  Andrew Stillwell,et al.  A 5-level flying capacitor multi-level converter with integrated auxiliary power supply and start-up , 2017, 2017 IEEE Applied Power Electronics Conference and Exposition (APEC).

[17]  Shahriar Mirabbasi,et al.  Fully Integrated Buck Converter With Fourth-Order Low-Pass Filter , 2017, IEEE Transactions on Power Electronics.

[18]  Robert J. Wood,et al.  Energetics of flapping-wing robotic insects: towards autonomous hovering flight , 2010, 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[19]  Eduard Alarcon,et al.  On the modeling of switched capacitor converters with multiple outputs , 2014, 2014 IEEE Applied Power Electronics Conference and Exposition - APEC 2014.

[20]  W.G. Dunford,et al.  A Fully Integrated 660 MHz Low-Swing Energy-Recycling DC–DC Converter , 2009, IEEE Transactions on Power Electronics.

[21]  Michiel Steyaert,et al.  A high speed, low voltage to high voltage level shifter in standard 1.2 V 0.13 μm CMOS , 2006 .

[22]  Gu-Yeon Wei,et al.  A fully integrated battery-connected switched-capacitor 4:1 voltage regulator with 70% peak efficiency using bottom-plate charge recycling , 2013, Proceedings of the IEEE 2013 Custom Integrated Circuits Conference.

[23]  S. Narendra,et al.  A 233-MHz 80%-87% efficient four-phase DC-DC converter utilizing air-core inductors on package , 2005, IEEE Journal of Solid-State Circuits.